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Linux/kernel/sched/core.c

  1 /*
  2  *  kernel/sched/core.c
  3  *
  4  *  Kernel scheduler and related syscalls
  5  *
  6  *  Copyright (C) 1991-2002  Linus Torvalds
  7  *
  8  *  1996-12-23  Modified by Dave Grothe to fix bugs in semaphores and
  9  *              make semaphores SMP safe
 10  *  1998-11-19  Implemented schedule_timeout() and related stuff
 11  *              by Andrea Arcangeli
 12  *  2002-01-04  New ultra-scalable O(1) scheduler by Ingo Molnar:
 13  *              hybrid priority-list and round-robin design with
 14  *              an array-switch method of distributing timeslices
 15  *              and per-CPU runqueues.  Cleanups and useful suggestions
 16  *              by Davide Libenzi, preemptible kernel bits by Robert Love.
 17  *  2003-09-03  Interactivity tuning by Con Kolivas.
 18  *  2004-04-02  Scheduler domains code by Nick Piggin
 19  *  2007-04-15  Work begun on replacing all interactivity tuning with a
 20  *              fair scheduling design by Con Kolivas.
 21  *  2007-05-05  Load balancing (smp-nice) and other improvements
 22  *              by Peter Williams
 23  *  2007-05-06  Interactivity improvements to CFS by Mike Galbraith
 24  *  2007-07-01  Group scheduling enhancements by Srivatsa Vaddagiri
 25  *  2007-11-29  RT balancing improvements by Steven Rostedt, Gregory Haskins,
 26  *              Thomas Gleixner, Mike Kravetz
 27  */
 28 
 29 #include <linux/kasan.h>
 30 #include <linux/mm.h>
 31 #include <linux/module.h>
 32 #include <linux/nmi.h>
 33 #include <linux/init.h>
 34 #include <linux/uaccess.h>
 35 #include <linux/highmem.h>
 36 #include <asm/mmu_context.h>
 37 #include <linux/interrupt.h>
 38 #include <linux/capability.h>
 39 #include <linux/completion.h>
 40 #include <linux/kernel_stat.h>
 41 #include <linux/debug_locks.h>
 42 #include <linux/perf_event.h>
 43 #include <linux/security.h>
 44 #include <linux/notifier.h>
 45 #include <linux/profile.h>
 46 #include <linux/freezer.h>
 47 #include <linux/vmalloc.h>
 48 #include <linux/blkdev.h>
 49 #include <linux/delay.h>
 50 #include <linux/pid_namespace.h>
 51 #include <linux/smp.h>
 52 #include <linux/threads.h>
 53 #include <linux/timer.h>
 54 #include <linux/rcupdate.h>
 55 #include <linux/cpu.h>
 56 #include <linux/cpuset.h>
 57 #include <linux/percpu.h>
 58 #include <linux/proc_fs.h>
 59 #include <linux/seq_file.h>
 60 #include <linux/sysctl.h>
 61 #include <linux/syscalls.h>
 62 #include <linux/times.h>
 63 #include <linux/tsacct_kern.h>
 64 #include <linux/kprobes.h>
 65 #include <linux/delayacct.h>
 66 #include <linux/unistd.h>
 67 #include <linux/pagemap.h>
 68 #include <linux/hrtimer.h>
 69 #include <linux/tick.h>
 70 #include <linux/ctype.h>
 71 #include <linux/ftrace.h>
 72 #include <linux/slab.h>
 73 #include <linux/init_task.h>
 74 #include <linux/context_tracking.h>
 75 #include <linux/compiler.h>
 76 #include <linux/frame.h>
 77 
 78 #include <asm/switch_to.h>
 79 #include <asm/tlb.h>
 80 #include <asm/irq_regs.h>
 81 #include <asm/mutex.h>
 82 #ifdef CONFIG_PARAVIRT
 83 #include <asm/paravirt.h>
 84 #endif
 85 
 86 #include "sched.h"
 87 #include "../workqueue_internal.h"
 88 #include "../smpboot.h"
 89 
 90 #define CREATE_TRACE_POINTS
 91 #include <trace/events/sched.h>
 92 
 93 DEFINE_MUTEX(sched_domains_mutex);
 94 DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
 95 
 96 static void update_rq_clock_task(struct rq *rq, s64 delta);
 97 
 98 void update_rq_clock(struct rq *rq)
 99 {
100         s64 delta;
101 
102         lockdep_assert_held(&rq->lock);
103 
104         if (rq->clock_skip_update & RQCF_ACT_SKIP)
105                 return;
106 
107         delta = sched_clock_cpu(cpu_of(rq)) - rq->clock;
108         if (delta < 0)
109                 return;
110         rq->clock += delta;
111         update_rq_clock_task(rq, delta);
112 }
113 
114 /*
115  * Debugging: various feature bits
116  */
117 
118 #define SCHED_FEAT(name, enabled)       \
119         (1UL << __SCHED_FEAT_##name) * enabled |
120 
121 const_debug unsigned int sysctl_sched_features =
122 #include "features.h"
123         0;
124 
125 #undef SCHED_FEAT
126 
127 /*
128  * Number of tasks to iterate in a single balance run.
129  * Limited because this is done with IRQs disabled.
130  */
131 const_debug unsigned int sysctl_sched_nr_migrate = 32;
132 
133 /*
134  * period over which we average the RT time consumption, measured
135  * in ms.
136  *
137  * default: 1s
138  */
139 const_debug unsigned int sysctl_sched_time_avg = MSEC_PER_SEC;
140 
141 /*
142  * period over which we measure -rt task cpu usage in us.
143  * default: 1s
144  */
145 unsigned int sysctl_sched_rt_period = 1000000;
146 
147 __read_mostly int scheduler_running;
148 
149 /*
150  * part of the period that we allow rt tasks to run in us.
151  * default: 0.95s
152  */
153 int sysctl_sched_rt_runtime = 950000;
154 
155 /* cpus with isolated domains */
156 cpumask_var_t cpu_isolated_map;
157 
158 /*
159  * this_rq_lock - lock this runqueue and disable interrupts.
160  */
161 static struct rq *this_rq_lock(void)
162         __acquires(rq->lock)
163 {
164         struct rq *rq;
165 
166         local_irq_disable();
167         rq = this_rq();
168         raw_spin_lock(&rq->lock);
169 
170         return rq;
171 }
172 
173 #ifdef CONFIG_SCHED_HRTICK
174 /*
175  * Use HR-timers to deliver accurate preemption points.
176  */
177 
178 static void hrtick_clear(struct rq *rq)
179 {
180         if (hrtimer_active(&rq->hrtick_timer))
181                 hrtimer_cancel(&rq->hrtick_timer);
182 }
183 
184 /*
185  * High-resolution timer tick.
186  * Runs from hardirq context with interrupts disabled.
187  */
188 static enum hrtimer_restart hrtick(struct hrtimer *timer)
189 {
190         struct rq *rq = container_of(timer, struct rq, hrtick_timer);
191 
192         WARN_ON_ONCE(cpu_of(rq) != smp_processor_id());
193 
194         raw_spin_lock(&rq->lock);
195         update_rq_clock(rq);
196         rq->curr->sched_class->task_tick(rq, rq->curr, 1);
197         raw_spin_unlock(&rq->lock);
198 
199         return HRTIMER_NORESTART;
200 }
201 
202 #ifdef CONFIG_SMP
203 
204 static void __hrtick_restart(struct rq *rq)
205 {
206         struct hrtimer *timer = &rq->hrtick_timer;
207 
208         hrtimer_start_expires(timer, HRTIMER_MODE_ABS_PINNED);
209 }
210 
211 /*
212  * called from hardirq (IPI) context
213  */
214 static void __hrtick_start(void *arg)
215 {
216         struct rq *rq = arg;
217 
218         raw_spin_lock(&rq->lock);
219         __hrtick_restart(rq);
220         rq->hrtick_csd_pending = 0;
221         raw_spin_unlock(&rq->lock);
222 }
223 
224 /*
225  * Called to set the hrtick timer state.
226  *
227  * called with rq->lock held and irqs disabled
228  */
229 void hrtick_start(struct rq *rq, u64 delay)
230 {
231         struct hrtimer *timer = &rq->hrtick_timer;
232         ktime_t time;
233         s64 delta;
234 
235         /*
236          * Don't schedule slices shorter than 10000ns, that just
237          * doesn't make sense and can cause timer DoS.
238          */
239         delta = max_t(s64, delay, 10000LL);
240         time = ktime_add_ns(timer->base->get_time(), delta);
241 
242         hrtimer_set_expires(timer, time);
243 
244         if (rq == this_rq()) {
245                 __hrtick_restart(rq);
246         } else if (!rq->hrtick_csd_pending) {
247                 smp_call_function_single_async(cpu_of(rq), &rq->hrtick_csd);
248                 rq->hrtick_csd_pending = 1;
249         }
250 }
251 
252 static int
253 hotplug_hrtick(struct notifier_block *nfb, unsigned long action, void *hcpu)
254 {
255         int cpu = (int)(long)hcpu;
256 
257         switch (action) {
258         case CPU_UP_CANCELED:
259         case CPU_UP_CANCELED_FROZEN:
260         case CPU_DOWN_PREPARE:
261         case CPU_DOWN_PREPARE_FROZEN:
262         case CPU_DEAD:
263         case CPU_DEAD_FROZEN:
264                 hrtick_clear(cpu_rq(cpu));
265                 return NOTIFY_OK;
266         }
267 
268         return NOTIFY_DONE;
269 }
270 
271 static __init void init_hrtick(void)
272 {
273         hotcpu_notifier(hotplug_hrtick, 0);
274 }
275 #else
276 /*
277  * Called to set the hrtick timer state.
278  *
279  * called with rq->lock held and irqs disabled
280  */
281 void hrtick_start(struct rq *rq, u64 delay)
282 {
283         /*
284          * Don't schedule slices shorter than 10000ns, that just
285          * doesn't make sense. Rely on vruntime for fairness.
286          */
287         delay = max_t(u64, delay, 10000LL);
288         hrtimer_start(&rq->hrtick_timer, ns_to_ktime(delay),
289                       HRTIMER_MODE_REL_PINNED);
290 }
291 
292 static inline void init_hrtick(void)
293 {
294 }
295 #endif /* CONFIG_SMP */
296 
297 static void init_rq_hrtick(struct rq *rq)
298 {
299 #ifdef CONFIG_SMP
300         rq->hrtick_csd_pending = 0;
301 
302         rq->hrtick_csd.flags = 0;
303         rq->hrtick_csd.func = __hrtick_start;
304         rq->hrtick_csd.info = rq;
305 #endif
306 
307         hrtimer_init(&rq->hrtick_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
308         rq->hrtick_timer.function = hrtick;
309 }
310 #else   /* CONFIG_SCHED_HRTICK */
311 static inline void hrtick_clear(struct rq *rq)
312 {
313 }
314 
315 static inline void init_rq_hrtick(struct rq *rq)
316 {
317 }
318 
319 static inline void init_hrtick(void)
320 {
321 }
322 #endif  /* CONFIG_SCHED_HRTICK */
323 
324 /*
325  * cmpxchg based fetch_or, macro so it works for different integer types
326  */
327 #define fetch_or(ptr, mask)                                             \
328         ({                                                              \
329                 typeof(ptr) _ptr = (ptr);                               \
330                 typeof(mask) _mask = (mask);                            \
331                 typeof(*_ptr) _old, _val = *_ptr;                       \
332                                                                         \
333                 for (;;) {                                              \
334                         _old = cmpxchg(_ptr, _val, _val | _mask);       \
335                         if (_old == _val)                               \
336                                 break;                                  \
337                         _val = _old;                                    \
338                 }                                                       \
339         _old;                                                           \
340 })
341 
342 #if defined(CONFIG_SMP) && defined(TIF_POLLING_NRFLAG)
343 /*
344  * Atomically set TIF_NEED_RESCHED and test for TIF_POLLING_NRFLAG,
345  * this avoids any races wrt polling state changes and thereby avoids
346  * spurious IPIs.
347  */
348 static bool set_nr_and_not_polling(struct task_struct *p)
349 {
350         struct thread_info *ti = task_thread_info(p);
351         return !(fetch_or(&ti->flags, _TIF_NEED_RESCHED) & _TIF_POLLING_NRFLAG);
352 }
353 
354 /*
355  * Atomically set TIF_NEED_RESCHED if TIF_POLLING_NRFLAG is set.
356  *
357  * If this returns true, then the idle task promises to call
358  * sched_ttwu_pending() and reschedule soon.
359  */
360 static bool set_nr_if_polling(struct task_struct *p)
361 {
362         struct thread_info *ti = task_thread_info(p);
363         typeof(ti->flags) old, val = READ_ONCE(ti->flags);
364 
365         for (;;) {
366                 if (!(val & _TIF_POLLING_NRFLAG))
367                         return false;
368                 if (val & _TIF_NEED_RESCHED)
369                         return true;
370                 old = cmpxchg(&ti->flags, val, val | _TIF_NEED_RESCHED);
371                 if (old == val)
372                         break;
373                 val = old;
374         }
375         return true;
376 }
377 
378 #else
379 static bool set_nr_and_not_polling(struct task_struct *p)
380 {
381         set_tsk_need_resched(p);
382         return true;
383 }
384 
385 #ifdef CONFIG_SMP
386 static bool set_nr_if_polling(struct task_struct *p)
387 {
388         return false;
389 }
390 #endif
391 #endif
392 
393 void wake_q_add(struct wake_q_head *head, struct task_struct *task)
394 {
395         struct wake_q_node *node = &task->wake_q;
396 
397         /*
398          * Atomically grab the task, if ->wake_q is !nil already it means
399          * its already queued (either by us or someone else) and will get the
400          * wakeup due to that.
401          *
402          * This cmpxchg() implies a full barrier, which pairs with the write
403          * barrier implied by the wakeup in wake_up_list().
404          */
405         if (cmpxchg(&node->next, NULL, WAKE_Q_TAIL))
406                 return;
407 
408         get_task_struct(task);
409 
410         /*
411          * The head is context local, there can be no concurrency.
412          */
413         *head->lastp = node;
414         head->lastp = &node->next;
415 }
416 
417 void wake_up_q(struct wake_q_head *head)
418 {
419         struct wake_q_node *node = head->first;
420 
421         while (node != WAKE_Q_TAIL) {
422                 struct task_struct *task;
423 
424                 task = container_of(node, struct task_struct, wake_q);
425                 BUG_ON(!task);
426                 /* task can safely be re-inserted now */
427                 node = node->next;
428                 task->wake_q.next = NULL;
429 
430                 /*
431                  * wake_up_process() implies a wmb() to pair with the queueing
432                  * in wake_q_add() so as not to miss wakeups.
433                  */
434                 wake_up_process(task);
435                 put_task_struct(task);
436         }
437 }
438 
439 /*
440  * resched_curr - mark rq's current task 'to be rescheduled now'.
441  *
442  * On UP this means the setting of the need_resched flag, on SMP it
443  * might also involve a cross-CPU call to trigger the scheduler on
444  * the target CPU.
445  */
446 void resched_curr(struct rq *rq)
447 {
448         struct task_struct *curr = rq->curr;
449         int cpu;
450 
451         lockdep_assert_held(&rq->lock);
452 
453         if (test_tsk_need_resched(curr))
454                 return;
455 
456         cpu = cpu_of(rq);
457 
458         if (cpu == smp_processor_id()) {
459                 set_tsk_need_resched(curr);
460                 set_preempt_need_resched();
461                 return;
462         }
463 
464         if (set_nr_and_not_polling(curr))
465                 smp_send_reschedule(cpu);
466         else
467                 trace_sched_wake_idle_without_ipi(cpu);
468 }
469 
470 void resched_cpu(int cpu)
471 {
472         struct rq *rq = cpu_rq(cpu);
473         unsigned long flags;
474 
475         if (!raw_spin_trylock_irqsave(&rq->lock, flags))
476                 return;
477         resched_curr(rq);
478         raw_spin_unlock_irqrestore(&rq->lock, flags);
479 }
480 
481 #ifdef CONFIG_SMP
482 #ifdef CONFIG_NO_HZ_COMMON
483 /*
484  * In the semi idle case, use the nearest busy cpu for migrating timers
485  * from an idle cpu.  This is good for power-savings.
486  *
487  * We don't do similar optimization for completely idle system, as
488  * selecting an idle cpu will add more delays to the timers than intended
489  * (as that cpu's timer base may not be uptodate wrt jiffies etc).
490  */
491 int get_nohz_timer_target(void)
492 {
493         int i, cpu = smp_processor_id();
494         struct sched_domain *sd;
495 
496         if (!idle_cpu(cpu) && is_housekeeping_cpu(cpu))
497                 return cpu;
498 
499         rcu_read_lock();
500         for_each_domain(cpu, sd) {
501                 for_each_cpu(i, sched_domain_span(sd)) {
502                         if (!idle_cpu(i) && is_housekeeping_cpu(cpu)) {
503                                 cpu = i;
504                                 goto unlock;
505                         }
506                 }
507         }
508 
509         if (!is_housekeeping_cpu(cpu))
510                 cpu = housekeeping_any_cpu();
511 unlock:
512         rcu_read_unlock();
513         return cpu;
514 }
515 /*
516  * When add_timer_on() enqueues a timer into the timer wheel of an
517  * idle CPU then this timer might expire before the next timer event
518  * which is scheduled to wake up that CPU. In case of a completely
519  * idle system the next event might even be infinite time into the
520  * future. wake_up_idle_cpu() ensures that the CPU is woken up and
521  * leaves the inner idle loop so the newly added timer is taken into
522  * account when the CPU goes back to idle and evaluates the timer
523  * wheel for the next timer event.
524  */
525 static void wake_up_idle_cpu(int cpu)
526 {
527         struct rq *rq = cpu_rq(cpu);
528 
529         if (cpu == smp_processor_id())
530                 return;
531 
532         if (set_nr_and_not_polling(rq->idle))
533                 smp_send_reschedule(cpu);
534         else
535                 trace_sched_wake_idle_without_ipi(cpu);
536 }
537 
538 static bool wake_up_full_nohz_cpu(int cpu)
539 {
540         /*
541          * We just need the target to call irq_exit() and re-evaluate
542          * the next tick. The nohz full kick at least implies that.
543          * If needed we can still optimize that later with an
544          * empty IRQ.
545          */
546         if (tick_nohz_full_cpu(cpu)) {
547                 if (cpu != smp_processor_id() ||
548                     tick_nohz_tick_stopped())
549                         tick_nohz_full_kick_cpu(cpu);
550                 return true;
551         }
552 
553         return false;
554 }
555 
556 void wake_up_nohz_cpu(int cpu)
557 {
558         if (!wake_up_full_nohz_cpu(cpu))
559                 wake_up_idle_cpu(cpu);
560 }
561 
562 static inline bool got_nohz_idle_kick(void)
563 {
564         int cpu = smp_processor_id();
565 
566         if (!test_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu)))
567                 return false;
568 
569         if (idle_cpu(cpu) && !need_resched())
570                 return true;
571 
572         /*
573          * We can't run Idle Load Balance on this CPU for this time so we
574          * cancel it and clear NOHZ_BALANCE_KICK
575          */
576         clear_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu));
577         return false;
578 }
579 
580 #else /* CONFIG_NO_HZ_COMMON */
581 
582 static inline bool got_nohz_idle_kick(void)
583 {
584         return false;
585 }
586 
587 #endif /* CONFIG_NO_HZ_COMMON */
588 
589 #ifdef CONFIG_NO_HZ_FULL
590 bool sched_can_stop_tick(struct rq *rq)
591 {
592         int fifo_nr_running;
593 
594         /* Deadline tasks, even if single, need the tick */
595         if (rq->dl.dl_nr_running)
596                 return false;
597 
598         /*
599          * If there are more than one RR tasks, we need the tick to effect the
600          * actual RR behaviour.
601          */
602         if (rq->rt.rr_nr_running) {
603                 if (rq->rt.rr_nr_running == 1)
604                         return true;
605                 else
606                         return false;
607         }
608 
609         /*
610          * If there's no RR tasks, but FIFO tasks, we can skip the tick, no
611          * forced preemption between FIFO tasks.
612          */
613         fifo_nr_running = rq->rt.rt_nr_running - rq->rt.rr_nr_running;
614         if (fifo_nr_running)
615                 return true;
616 
617         /*
618          * If there are no DL,RR/FIFO tasks, there must only be CFS tasks left;
619          * if there's more than one we need the tick for involuntary
620          * preemption.
621          */
622         if (rq->nr_running > 1)
623                 return false;
624 
625         return true;
626 }
627 #endif /* CONFIG_NO_HZ_FULL */
628 
629 void sched_avg_update(struct rq *rq)
630 {
631         s64 period = sched_avg_period();
632 
633         while ((s64)(rq_clock(rq) - rq->age_stamp) > period) {
634                 /*
635                  * Inline assembly required to prevent the compiler
636                  * optimising this loop into a divmod call.
637                  * See __iter_div_u64_rem() for another example of this.
638                  */
639                 asm("" : "+rm" (rq->age_stamp));
640                 rq->age_stamp += period;
641                 rq->rt_avg /= 2;
642         }
643 }
644 
645 #endif /* CONFIG_SMP */
646 
647 #if defined(CONFIG_RT_GROUP_SCHED) || (defined(CONFIG_FAIR_GROUP_SCHED) && \
648                         (defined(CONFIG_SMP) || defined(CONFIG_CFS_BANDWIDTH)))
649 /*
650  * Iterate task_group tree rooted at *from, calling @down when first entering a
651  * node and @up when leaving it for the final time.
652  *
653  * Caller must hold rcu_lock or sufficient equivalent.
654  */
655 int walk_tg_tree_from(struct task_group *from,
656                              tg_visitor down, tg_visitor up, void *data)
657 {
658         struct task_group *parent, *child;
659         int ret;
660 
661         parent = from;
662 
663 down:
664         ret = (*down)(parent, data);
665         if (ret)
666                 goto out;
667         list_for_each_entry_rcu(child, &parent->children, siblings) {
668                 parent = child;
669                 goto down;
670 
671 up:
672                 continue;
673         }
674         ret = (*up)(parent, data);
675         if (ret || parent == from)
676                 goto out;
677 
678         child = parent;
679         parent = parent->parent;
680         if (parent)
681                 goto up;
682 out:
683         return ret;
684 }
685 
686 int tg_nop(struct task_group *tg, void *data)
687 {
688         return 0;
689 }
690 #endif
691 
692 static void set_load_weight(struct task_struct *p)
693 {
694         int prio = p->static_prio - MAX_RT_PRIO;
695         struct load_weight *load = &p->se.load;
696 
697         /*
698          * SCHED_IDLE tasks get minimal weight:
699          */
700         if (idle_policy(p->policy)) {
701                 load->weight = scale_load(WEIGHT_IDLEPRIO);
702                 load->inv_weight = WMULT_IDLEPRIO;
703                 return;
704         }
705 
706         load->weight = scale_load(sched_prio_to_weight[prio]);
707         load->inv_weight = sched_prio_to_wmult[prio];
708 }
709 
710 static inline void enqueue_task(struct rq *rq, struct task_struct *p, int flags)
711 {
712         update_rq_clock(rq);
713         if (!(flags & ENQUEUE_RESTORE))
714                 sched_info_queued(rq, p);
715         p->sched_class->enqueue_task(rq, p, flags);
716 }
717 
718 static inline void dequeue_task(struct rq *rq, struct task_struct *p, int flags)
719 {
720         update_rq_clock(rq);
721         if (!(flags & DEQUEUE_SAVE))
722                 sched_info_dequeued(rq, p);
723         p->sched_class->dequeue_task(rq, p, flags);
724 }
725 
726 void activate_task(struct rq *rq, struct task_struct *p, int flags)
727 {
728         if (task_contributes_to_load(p))
729                 rq->nr_uninterruptible--;
730 
731         enqueue_task(rq, p, flags);
732 }
733 
734 void deactivate_task(struct rq *rq, struct task_struct *p, int flags)
735 {
736         if (task_contributes_to_load(p))
737                 rq->nr_uninterruptible++;
738 
739         dequeue_task(rq, p, flags);
740 }
741 
742 static void update_rq_clock_task(struct rq *rq, s64 delta)
743 {
744 /*
745  * In theory, the compile should just see 0 here, and optimize out the call
746  * to sched_rt_avg_update. But I don't trust it...
747  */
748 #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
749         s64 steal = 0, irq_delta = 0;
750 #endif
751 #ifdef CONFIG_IRQ_TIME_ACCOUNTING
752         irq_delta = irq_time_read(cpu_of(rq)) - rq->prev_irq_time;
753 
754         /*
755          * Since irq_time is only updated on {soft,}irq_exit, we might run into
756          * this case when a previous update_rq_clock() happened inside a
757          * {soft,}irq region.
758          *
759          * When this happens, we stop ->clock_task and only update the
760          * prev_irq_time stamp to account for the part that fit, so that a next
761          * update will consume the rest. This ensures ->clock_task is
762          * monotonic.
763          *
764          * It does however cause some slight miss-attribution of {soft,}irq
765          * time, a more accurate solution would be to update the irq_time using
766          * the current rq->clock timestamp, except that would require using
767          * atomic ops.
768          */
769         if (irq_delta > delta)
770                 irq_delta = delta;
771 
772         rq->prev_irq_time += irq_delta;
773         delta -= irq_delta;
774 #endif
775 #ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
776         if (static_key_false((&paravirt_steal_rq_enabled))) {
777                 steal = paravirt_steal_clock(cpu_of(rq));
778                 steal -= rq->prev_steal_time_rq;
779 
780                 if (unlikely(steal > delta))
781                         steal = delta;
782 
783                 rq->prev_steal_time_rq += steal;
784                 delta -= steal;
785         }
786 #endif
787 
788         rq->clock_task += delta;
789 
790 #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
791         if ((irq_delta + steal) && sched_feat(NONTASK_CAPACITY))
792                 sched_rt_avg_update(rq, irq_delta + steal);
793 #endif
794 }
795 
796 void sched_set_stop_task(int cpu, struct task_struct *stop)
797 {
798         struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
799         struct task_struct *old_stop = cpu_rq(cpu)->stop;
800 
801         if (stop) {
802                 /*
803                  * Make it appear like a SCHED_FIFO task, its something
804                  * userspace knows about and won't get confused about.
805                  *
806                  * Also, it will make PI more or less work without too
807                  * much confusion -- but then, stop work should not
808                  * rely on PI working anyway.
809                  */
810                 sched_setscheduler_nocheck(stop, SCHED_FIFO, &param);
811 
812                 stop->sched_class = &stop_sched_class;
813         }
814 
815         cpu_rq(cpu)->stop = stop;
816 
817         if (old_stop) {
818                 /*
819                  * Reset it back to a normal scheduling class so that
820                  * it can die in pieces.
821                  */
822                 old_stop->sched_class = &rt_sched_class;
823         }
824 }
825 
826 /*
827  * __normal_prio - return the priority that is based on the static prio
828  */
829 static inline int __normal_prio(struct task_struct *p)
830 {
831         return p->static_prio;
832 }
833 
834 /*
835  * Calculate the expected normal priority: i.e. priority
836  * without taking RT-inheritance into account. Might be
837  * boosted by interactivity modifiers. Changes upon fork,
838  * setprio syscalls, and whenever the interactivity
839  * estimator recalculates.
840  */
841 static inline int normal_prio(struct task_struct *p)
842 {
843         int prio;
844 
845         if (task_has_dl_policy(p))
846                 prio = MAX_DL_PRIO-1;
847         else if (task_has_rt_policy(p))
848                 prio = MAX_RT_PRIO-1 - p->rt_priority;
849         else
850                 prio = __normal_prio(p);
851         return prio;
852 }
853 
854 /*
855  * Calculate the current priority, i.e. the priority
856  * taken into account by the scheduler. This value might
857  * be boosted by RT tasks, or might be boosted by
858  * interactivity modifiers. Will be RT if the task got
859  * RT-boosted. If not then it returns p->normal_prio.
860  */
861 static int effective_prio(struct task_struct *p)
862 {
863         p->normal_prio = normal_prio(p);
864         /*
865          * If we are RT tasks or we were boosted to RT priority,
866          * keep the priority unchanged. Otherwise, update priority
867          * to the normal priority:
868          */
869         if (!rt_prio(p->prio))
870                 return p->normal_prio;
871         return p->prio;
872 }
873 
874 /**
875  * task_curr - is this task currently executing on a CPU?
876  * @p: the task in question.
877  *
878  * Return: 1 if the task is currently executing. 0 otherwise.
879  */
880 inline int task_curr(const struct task_struct *p)
881 {
882         return cpu_curr(task_cpu(p)) == p;
883 }
884 
885 /*
886  * switched_from, switched_to and prio_changed must _NOT_ drop rq->lock,
887  * use the balance_callback list if you want balancing.
888  *
889  * this means any call to check_class_changed() must be followed by a call to
890  * balance_callback().
891  */
892 static inline void check_class_changed(struct rq *rq, struct task_struct *p,
893                                        const struct sched_class *prev_class,
894                                        int oldprio)
895 {
896         if (prev_class != p->sched_class) {
897                 if (prev_class->switched_from)
898                         prev_class->switched_from(rq, p);
899 
900                 p->sched_class->switched_to(rq, p);
901         } else if (oldprio != p->prio || dl_task(p))
902                 p->sched_class->prio_changed(rq, p, oldprio);
903 }
904 
905 void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags)
906 {
907         const struct sched_class *class;
908 
909         if (p->sched_class == rq->curr->sched_class) {
910                 rq->curr->sched_class->check_preempt_curr(rq, p, flags);
911         } else {
912                 for_each_class(class) {
913                         if (class == rq->curr->sched_class)
914                                 break;
915                         if (class == p->sched_class) {
916                                 resched_curr(rq);
917                                 break;
918                         }
919                 }
920         }
921 
922         /*
923          * A queue event has occurred, and we're going to schedule.  In
924          * this case, we can save a useless back to back clock update.
925          */
926         if (task_on_rq_queued(rq->curr) && test_tsk_need_resched(rq->curr))
927                 rq_clock_skip_update(rq, true);
928 }
929 
930 #ifdef CONFIG_SMP
931 /*
932  * This is how migration works:
933  *
934  * 1) we invoke migration_cpu_stop() on the target CPU using
935  *    stop_one_cpu().
936  * 2) stopper starts to run (implicitly forcing the migrated thread
937  *    off the CPU)
938  * 3) it checks whether the migrated task is still in the wrong runqueue.
939  * 4) if it's in the wrong runqueue then the migration thread removes
940  *    it and puts it into the right queue.
941  * 5) stopper completes and stop_one_cpu() returns and the migration
942  *    is done.
943  */
944 
945 /*
946  * move_queued_task - move a queued task to new rq.
947  *
948  * Returns (locked) new rq. Old rq's lock is released.
949  */
950 static struct rq *move_queued_task(struct rq *rq, struct task_struct *p, int new_cpu)
951 {
952         lockdep_assert_held(&rq->lock);
953 
954         p->on_rq = TASK_ON_RQ_MIGRATING;
955         dequeue_task(rq, p, 0);
956         set_task_cpu(p, new_cpu);
957         raw_spin_unlock(&rq->lock);
958 
959         rq = cpu_rq(new_cpu);
960 
961         raw_spin_lock(&rq->lock);
962         BUG_ON(task_cpu(p) != new_cpu);
963         enqueue_task(rq, p, 0);
964         p->on_rq = TASK_ON_RQ_QUEUED;
965         check_preempt_curr(rq, p, 0);
966 
967         return rq;
968 }
969 
970 struct migration_arg {
971         struct task_struct *task;
972         int dest_cpu;
973 };
974 
975 /*
976  * Move (not current) task off this cpu, onto dest cpu. We're doing
977  * this because either it can't run here any more (set_cpus_allowed()
978  * away from this CPU, or CPU going down), or because we're
979  * attempting to rebalance this task on exec (sched_exec).
980  *
981  * So we race with normal scheduler movements, but that's OK, as long
982  * as the task is no longer on this CPU.
983  */
984 static struct rq *__migrate_task(struct rq *rq, struct task_struct *p, int dest_cpu)
985 {
986         if (unlikely(!cpu_active(dest_cpu)))
987                 return rq;
988 
989         /* Affinity changed (again). */
990         if (!cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p)))
991                 return rq;
992 
993         rq = move_queued_task(rq, p, dest_cpu);
994 
995         return rq;
996 }
997 
998 /*
999  * migration_cpu_stop - this will be executed by a highprio stopper thread
1000  * and performs thread migration by bumping thread off CPU then
1001  * 'pushing' onto another runqueue.
1002  */
1003 static int migration_cpu_stop(void *data)
1004 {
1005         struct migration_arg *arg = data;
1006         struct task_struct *p = arg->task;
1007         struct rq *rq = this_rq();
1008 
1009         /*
1010          * The original target cpu might have gone down and we might
1011          * be on another cpu but it doesn't matter.
1012          */
1013         local_irq_disable();
1014         /*
1015          * We need to explicitly wake pending tasks before running
1016          * __migrate_task() such that we will not miss enforcing cpus_allowed
1017          * during wakeups, see set_cpus_allowed_ptr()'s TASK_WAKING test.
1018          */
1019         sched_ttwu_pending();
1020 
1021         raw_spin_lock(&p->pi_lock);
1022         raw_spin_lock(&rq->lock);
1023         /*
1024          * If task_rq(p) != rq, it cannot be migrated here, because we're
1025          * holding rq->lock, if p->on_rq == 0 it cannot get enqueued because
1026          * we're holding p->pi_lock.
1027          */
1028         if (task_rq(p) == rq && task_on_rq_queued(p))
1029                 rq = __migrate_task(rq, p, arg->dest_cpu);
1030         raw_spin_unlock(&rq->lock);
1031         raw_spin_unlock(&p->pi_lock);
1032 
1033         local_irq_enable();
1034         return 0;
1035 }
1036 
1037 /*
1038  * sched_class::set_cpus_allowed must do the below, but is not required to
1039  * actually call this function.
1040  */
1041 void set_cpus_allowed_common(struct task_struct *p, const struct cpumask *new_mask)
1042 {
1043         cpumask_copy(&p->cpus_allowed, new_mask);
1044         p->nr_cpus_allowed = cpumask_weight(new_mask);
1045 }
1046 
1047 void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask)
1048 {
1049         struct rq *rq = task_rq(p);
1050         bool queued, running;
1051 
1052         lockdep_assert_held(&p->pi_lock);
1053 
1054         queued = task_on_rq_queued(p);
1055         running = task_current(rq, p);
1056 
1057         if (queued) {
1058                 /*
1059                  * Because __kthread_bind() calls this on blocked tasks without
1060                  * holding rq->lock.
1061                  */
1062                 lockdep_assert_held(&rq->lock);
1063                 dequeue_task(rq, p, DEQUEUE_SAVE);
1064         }
1065         if (running)
1066                 put_prev_task(rq, p);
1067 
1068         p->sched_class->set_cpus_allowed(p, new_mask);
1069 
1070         if (running)
1071                 p->sched_class->set_curr_task(rq);
1072         if (queued)
1073                 enqueue_task(rq, p, ENQUEUE_RESTORE);
1074 }
1075 
1076 /*
1077  * Change a given task's CPU affinity. Migrate the thread to a
1078  * proper CPU and schedule it away if the CPU it's executing on
1079  * is removed from the allowed bitmask.
1080  *
1081  * NOTE: the caller must have a valid reference to the task, the
1082  * task must not exit() & deallocate itself prematurely. The
1083  * call is not atomic; no spinlocks may be held.
1084  */
1085 static int __set_cpus_allowed_ptr(struct task_struct *p,
1086                                   const struct cpumask *new_mask, bool check)
1087 {
1088         unsigned long flags;
1089         struct rq *rq;
1090         unsigned int dest_cpu;
1091         int ret = 0;
1092 
1093         rq = task_rq_lock(p, &flags);
1094 
1095         /*
1096          * Must re-check here, to close a race against __kthread_bind(),
1097          * sched_setaffinity() is not guaranteed to observe the flag.
1098          */
1099         if (check && (p->flags & PF_NO_SETAFFINITY)) {
1100                 ret = -EINVAL;
1101                 goto out;
1102         }
1103 
1104         if (cpumask_equal(&p->cpus_allowed, new_mask))
1105                 goto out;
1106 
1107         if (!cpumask_intersects(new_mask, cpu_active_mask)) {
1108                 ret = -EINVAL;
1109                 goto out;
1110         }
1111 
1112         do_set_cpus_allowed(p, new_mask);
1113 
1114         /* Can the task run on the task's current CPU? If so, we're done */
1115         if (cpumask_test_cpu(task_cpu(p), new_mask))
1116                 goto out;
1117 
1118         dest_cpu = cpumask_any_and(cpu_active_mask, new_mask);
1119         if (task_running(rq, p) || p->state == TASK_WAKING) {
1120                 struct migration_arg arg = { p, dest_cpu };
1121                 /* Need help from migration thread: drop lock and wait. */
1122                 task_rq_unlock(rq, p, &flags);
1123                 stop_one_cpu(cpu_of(rq), migration_cpu_stop, &arg);
1124                 tlb_migrate_finish(p->mm);
1125                 return 0;
1126         } else if (task_on_rq_queued(p)) {
1127                 /*
1128                  * OK, since we're going to drop the lock immediately
1129                  * afterwards anyway.
1130                  */
1131                 lockdep_unpin_lock(&rq->lock);
1132                 rq = move_queued_task(rq, p, dest_cpu);
1133                 lockdep_pin_lock(&rq->lock);
1134         }
1135 out:
1136         task_rq_unlock(rq, p, &flags);
1137 
1138         return ret;
1139 }
1140 
1141 int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask)
1142 {
1143         return __set_cpus_allowed_ptr(p, new_mask, false);
1144 }
1145 EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr);
1146 
1147 void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
1148 {
1149 #ifdef CONFIG_SCHED_DEBUG
1150         /*
1151          * We should never call set_task_cpu() on a blocked task,
1152          * ttwu() will sort out the placement.
1153          */
1154         WARN_ON_ONCE(p->state != TASK_RUNNING && p->state != TASK_WAKING &&
1155                         !p->on_rq);
1156 
1157         /*
1158          * Migrating fair class task must have p->on_rq = TASK_ON_RQ_MIGRATING,
1159          * because schedstat_wait_{start,end} rebase migrating task's wait_start
1160          * time relying on p->on_rq.
1161          */
1162         WARN_ON_ONCE(p->state == TASK_RUNNING &&
1163                      p->sched_class == &fair_sched_class &&
1164                      (p->on_rq && !task_on_rq_migrating(p)));
1165 
1166 #ifdef CONFIG_LOCKDEP
1167         /*
1168          * The caller should hold either p->pi_lock or rq->lock, when changing
1169          * a task's CPU. ->pi_lock for waking tasks, rq->lock for runnable tasks.
1170          *
1171          * sched_move_task() holds both and thus holding either pins the cgroup,
1172          * see task_group().
1173          *
1174          * Furthermore, all task_rq users should acquire both locks, see
1175          * task_rq_lock().
1176          */
1177         WARN_ON_ONCE(debug_locks && !(lockdep_is_held(&p->pi_lock) ||
1178                                       lockdep_is_held(&task_rq(p)->lock)));
1179 #endif
1180 #endif
1181 
1182         trace_sched_migrate_task(p, new_cpu);
1183 
1184         if (task_cpu(p) != new_cpu) {
1185                 if (p->sched_class->migrate_task_rq)
1186                         p->sched_class->migrate_task_rq(p);
1187                 p->se.nr_migrations++;
1188                 perf_event_task_migrate(p);
1189         }
1190 
1191         __set_task_cpu(p, new_cpu);
1192 }
1193 
1194 static void __migrate_swap_task(struct task_struct *p, int cpu)
1195 {
1196         if (task_on_rq_queued(p)) {
1197                 struct rq *src_rq, *dst_rq;
1198 
1199                 src_rq = task_rq(p);
1200                 dst_rq = cpu_rq(cpu);
1201 
1202                 p->on_rq = TASK_ON_RQ_MIGRATING;
1203                 deactivate_task(src_rq, p, 0);
1204                 set_task_cpu(p, cpu);
1205                 activate_task(dst_rq, p, 0);
1206                 p->on_rq = TASK_ON_RQ_QUEUED;
1207                 check_preempt_curr(dst_rq, p, 0);
1208         } else {
1209                 /*
1210                  * Task isn't running anymore; make it appear like we migrated
1211                  * it before it went to sleep. This means on wakeup we make the
1212                  * previous cpu our targer instead of where it really is.
1213                  */
1214                 p->wake_cpu = cpu;
1215         }
1216 }
1217 
1218 struct migration_swap_arg {
1219         struct task_struct *src_task, *dst_task;
1220         int src_cpu, dst_cpu;
1221 };
1222 
1223 static int migrate_swap_stop(void *data)
1224 {
1225         struct migration_swap_arg *arg = data;
1226         struct rq *src_rq, *dst_rq;
1227         int ret = -EAGAIN;
1228 
1229         if (!cpu_active(arg->src_cpu) || !cpu_active(arg->dst_cpu))
1230                 return -EAGAIN;
1231 
1232         src_rq = cpu_rq(arg->src_cpu);
1233         dst_rq = cpu_rq(arg->dst_cpu);
1234 
1235         double_raw_lock(&arg->src_task->pi_lock,
1236                         &arg->dst_task->pi_lock);
1237         double_rq_lock(src_rq, dst_rq);
1238 
1239         if (task_cpu(arg->dst_task) != arg->dst_cpu)
1240                 goto unlock;
1241 
1242         if (task_cpu(arg->src_task) != arg->src_cpu)
1243                 goto unlock;
1244 
1245         if (!cpumask_test_cpu(arg->dst_cpu, tsk_cpus_allowed(arg->src_task)))
1246                 goto unlock;
1247 
1248         if (!cpumask_test_cpu(arg->src_cpu, tsk_cpus_allowed(arg->dst_task)))
1249                 goto unlock;
1250 
1251         __migrate_swap_task(arg->src_task, arg->dst_cpu);
1252         __migrate_swap_task(arg->dst_task, arg->src_cpu);
1253 
1254         ret = 0;
1255 
1256 unlock:
1257         double_rq_unlock(src_rq, dst_rq);
1258         raw_spin_unlock(&arg->dst_task->pi_lock);
1259         raw_spin_unlock(&arg->src_task->pi_lock);
1260 
1261         return ret;
1262 }
1263 
1264 /*
1265  * Cross migrate two tasks
1266  */
1267 int migrate_swap(struct task_struct *cur, struct task_struct *p)
1268 {
1269         struct migration_swap_arg arg;
1270         int ret = -EINVAL;
1271 
1272         arg = (struct migration_swap_arg){
1273                 .src_task = cur,
1274                 .src_cpu = task_cpu(cur),
1275                 .dst_task = p,
1276                 .dst_cpu = task_cpu(p),
1277         };
1278 
1279         if (arg.src_cpu == arg.dst_cpu)
1280                 goto out;
1281 
1282         /*
1283          * These three tests are all lockless; this is OK since all of them
1284          * will be re-checked with proper locks held further down the line.
1285          */
1286         if (!cpu_active(arg.src_cpu) || !cpu_active(arg.dst_cpu))
1287                 goto out;
1288 
1289         if (!cpumask_test_cpu(arg.dst_cpu, tsk_cpus_allowed(arg.src_task)))
1290                 goto out;
1291 
1292         if (!cpumask_test_cpu(arg.src_cpu, tsk_cpus_allowed(arg.dst_task)))
1293                 goto out;
1294 
1295         trace_sched_swap_numa(cur, arg.src_cpu, p, arg.dst_cpu);
1296         ret = stop_two_cpus(arg.dst_cpu, arg.src_cpu, migrate_swap_stop, &arg);
1297 
1298 out:
1299         return ret;
1300 }
1301 
1302 /*
1303  * wait_task_inactive - wait for a thread to unschedule.
1304  *
1305  * If @match_state is nonzero, it's the @p->state value just checked and
1306  * not expected to change.  If it changes, i.e. @p might have woken up,
1307  * then return zero.  When we succeed in waiting for @p to be off its CPU,
1308  * we return a positive number (its total switch count).  If a second call
1309  * a short while later returns the same number, the caller can be sure that
1310  * @p has remained unscheduled the whole time.
1311  *
1312  * The caller must ensure that the task *will* unschedule sometime soon,
1313  * else this function might spin for a *long* time. This function can't
1314  * be called with interrupts off, or it may introduce deadlock with
1315  * smp_call_function() if an IPI is sent by the same process we are
1316  * waiting to become inactive.
1317  */
1318 unsigned long wait_task_inactive(struct task_struct *p, long match_state)
1319 {
1320         unsigned long flags;
1321         int running, queued;
1322         unsigned long ncsw;
1323         struct rq *rq;
1324 
1325         for (;;) {
1326                 /*
1327                  * We do the initial early heuristics without holding
1328                  * any task-queue locks at all. We'll only try to get
1329                  * the runqueue lock when things look like they will
1330                  * work out!
1331                  */
1332                 rq = task_rq(p);
1333 
1334                 /*
1335                  * If the task is actively running on another CPU
1336                  * still, just relax and busy-wait without holding
1337                  * any locks.
1338                  *
1339                  * NOTE! Since we don't hold any locks, it's not
1340                  * even sure that "rq" stays as the right runqueue!
1341                  * But we don't care, since "task_running()" will
1342                  * return false if the runqueue has changed and p
1343                  * is actually now running somewhere else!
1344                  */
1345                 while (task_running(rq, p)) {
1346                         if (match_state && unlikely(p->state != match_state))
1347                                 return 0;
1348                         cpu_relax();
1349                 }
1350 
1351                 /*
1352                  * Ok, time to look more closely! We need the rq
1353                  * lock now, to be *sure*. If we're wrong, we'll
1354                  * just go back and repeat.
1355                  */
1356                 rq = task_rq_lock(p, &flags);
1357                 trace_sched_wait_task(p);
1358                 running = task_running(rq, p);
1359                 queued = task_on_rq_queued(p);
1360                 ncsw = 0;
1361                 if (!match_state || p->state == match_state)
1362                         ncsw = p->nvcsw | LONG_MIN; /* sets MSB */
1363                 task_rq_unlock(rq, p, &flags);
1364 
1365                 /*
1366                  * If it changed from the expected state, bail out now.
1367                  */
1368                 if (unlikely(!ncsw))
1369                         break;
1370 
1371                 /*
1372                  * Was it really running after all now that we
1373                  * checked with the proper locks actually held?
1374                  *
1375                  * Oops. Go back and try again..
1376                  */
1377                 if (unlikely(running)) {
1378                         cpu_relax();
1379                         continue;
1380                 }
1381 
1382                 /*
1383                  * It's not enough that it's not actively running,
1384                  * it must be off the runqueue _entirely_, and not
1385                  * preempted!
1386                  *
1387                  * So if it was still runnable (but just not actively
1388                  * running right now), it's preempted, and we should
1389                  * yield - it could be a while.
1390                  */
1391                 if (unlikely(queued)) {
1392                         ktime_t to = ktime_set(0, NSEC_PER_SEC/HZ);
1393 
1394                         set_current_state(TASK_UNINTERRUPTIBLE);
1395                         schedule_hrtimeout(&to, HRTIMER_MODE_REL);
1396                         continue;
1397                 }
1398 
1399                 /*
1400                  * Ahh, all good. It wasn't running, and it wasn't
1401                  * runnable, which means that it will never become
1402                  * running in the future either. We're all done!
1403                  */
1404                 break;
1405         }
1406 
1407         return ncsw;
1408 }
1409 
1410 /***
1411  * kick_process - kick a running thread to enter/exit the kernel
1412  * @p: the to-be-kicked thread
1413  *
1414  * Cause a process which is running on another CPU to enter
1415  * kernel-mode, without any delay. (to get signals handled.)
1416  *
1417  * NOTE: this function doesn't have to take the runqueue lock,
1418  * because all it wants to ensure is that the remote task enters
1419  * the kernel. If the IPI races and the task has been migrated
1420  * to another CPU then no harm is done and the purpose has been
1421  * achieved as well.
1422  */
1423 void kick_process(struct task_struct *p)
1424 {
1425         int cpu;
1426 
1427         preempt_disable();
1428         cpu = task_cpu(p);
1429         if ((cpu != smp_processor_id()) && task_curr(p))
1430                 smp_send_reschedule(cpu);
1431         preempt_enable();
1432 }
1433 EXPORT_SYMBOL_GPL(kick_process);
1434 
1435 /*
1436  * ->cpus_allowed is protected by both rq->lock and p->pi_lock
1437  */
1438 static int select_fallback_rq(int cpu, struct task_struct *p)
1439 {
1440         int nid = cpu_to_node(cpu);
1441         const struct cpumask *nodemask = NULL;
1442         enum { cpuset, possible, fail } state = cpuset;
1443         int dest_cpu;
1444 
1445         /*
1446          * If the node that the cpu is on has been offlined, cpu_to_node()
1447          * will return -1. There is no cpu on the node, and we should
1448          * select the cpu on the other node.
1449          */
1450         if (nid != -1) {
1451                 nodemask = cpumask_of_node(nid);
1452 
1453                 /* Look for allowed, online CPU in same node. */
1454                 for_each_cpu(dest_cpu, nodemask) {
1455                         if (!cpu_online(dest_cpu))
1456                                 continue;
1457                         if (!cpu_active(dest_cpu))
1458                                 continue;
1459                         if (cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p)))
1460                                 return dest_cpu;
1461                 }
1462         }
1463 
1464         for (;;) {
1465                 /* Any allowed, online CPU? */
1466                 for_each_cpu(dest_cpu, tsk_cpus_allowed(p)) {
1467                         if (!cpu_online(dest_cpu))
1468                                 continue;
1469                         if (!cpu_active(dest_cpu))
1470                                 continue;
1471                         goto out;
1472                 }
1473 
1474                 /* No more Mr. Nice Guy. */
1475                 switch (state) {
1476                 case cpuset:
1477                         if (IS_ENABLED(CONFIG_CPUSETS)) {
1478                                 cpuset_cpus_allowed_fallback(p);
1479                                 state = possible;
1480                                 break;
1481                         }
1482                         /* fall-through */
1483                 case possible:
1484                         do_set_cpus_allowed(p, cpu_possible_mask);
1485                         state = fail;
1486                         break;
1487 
1488                 case fail:
1489                         BUG();
1490                         break;
1491                 }
1492         }
1493 
1494 out:
1495         if (state != cpuset) {
1496                 /*
1497                  * Don't tell them about moving exiting tasks or
1498                  * kernel threads (both mm NULL), since they never
1499                  * leave kernel.
1500                  */
1501                 if (p->mm && printk_ratelimit()) {
1502                         printk_deferred("process %d (%s) no longer affine to cpu%d\n",
1503                                         task_pid_nr(p), p->comm, cpu);
1504                 }
1505         }
1506 
1507         return dest_cpu;
1508 }
1509 
1510 /*
1511  * The caller (fork, wakeup) owns p->pi_lock, ->cpus_allowed is stable.
1512  */
1513 static inline
1514 int select_task_rq(struct task_struct *p, int cpu, int sd_flags, int wake_flags)
1515 {
1516         lockdep_assert_held(&p->pi_lock);
1517 
1518         if (p->nr_cpus_allowed > 1)
1519                 cpu = p->sched_class->select_task_rq(p, cpu, sd_flags, wake_flags);
1520 
1521         /*
1522          * In order not to call set_task_cpu() on a blocking task we need
1523          * to rely on ttwu() to place the task on a valid ->cpus_allowed
1524          * cpu.
1525          *
1526          * Since this is common to all placement strategies, this lives here.
1527          *
1528          * [ this allows ->select_task() to simply return task_cpu(p) and
1529          *   not worry about this generic constraint ]
1530          */
1531         if (unlikely(!cpumask_test_cpu(cpu, tsk_cpus_allowed(p)) ||
1532                      !cpu_online(cpu)))
1533                 cpu = select_fallback_rq(task_cpu(p), p);
1534 
1535         return cpu;
1536 }
1537 
1538 static void update_avg(u64 *avg, u64 sample)
1539 {
1540         s64 diff = sample - *avg;
1541         *avg += diff >> 3;
1542 }
1543 
1544 #else
1545 
1546 static inline int __set_cpus_allowed_ptr(struct task_struct *p,
1547                                          const struct cpumask *new_mask, bool check)
1548 {
1549         return set_cpus_allowed_ptr(p, new_mask);
1550 }
1551 
1552 #endif /* CONFIG_SMP */
1553 
1554 static void
1555 ttwu_stat(struct task_struct *p, int cpu, int wake_flags)
1556 {
1557 #ifdef CONFIG_SCHEDSTATS
1558         struct rq *rq = this_rq();
1559 
1560 #ifdef CONFIG_SMP
1561         int this_cpu = smp_processor_id();
1562 
1563         if (cpu == this_cpu) {
1564                 schedstat_inc(rq, ttwu_local);
1565                 schedstat_inc(p, se.statistics.nr_wakeups_local);
1566         } else {
1567                 struct sched_domain *sd;
1568 
1569                 schedstat_inc(p, se.statistics.nr_wakeups_remote);
1570                 rcu_read_lock();
1571                 for_each_domain(this_cpu, sd) {
1572                         if (cpumask_test_cpu(cpu, sched_domain_span(sd))) {
1573                                 schedstat_inc(sd, ttwu_wake_remote);
1574                                 break;
1575                         }
1576                 }
1577                 rcu_read_unlock();
1578         }
1579 
1580         if (wake_flags & WF_MIGRATED)
1581                 schedstat_inc(p, se.statistics.nr_wakeups_migrate);
1582 
1583 #endif /* CONFIG_SMP */
1584 
1585         schedstat_inc(rq, ttwu_count);
1586         schedstat_inc(p, se.statistics.nr_wakeups);
1587 
1588         if (wake_flags & WF_SYNC)
1589                 schedstat_inc(p, se.statistics.nr_wakeups_sync);
1590 
1591 #endif /* CONFIG_SCHEDSTATS */
1592 }
1593 
1594 static inline void ttwu_activate(struct rq *rq, struct task_struct *p, int en_flags)
1595 {
1596         activate_task(rq, p, en_flags);
1597         p->on_rq = TASK_ON_RQ_QUEUED;
1598 
1599         /* if a worker is waking up, notify workqueue */
1600         if (p->flags & PF_WQ_WORKER)
1601                 wq_worker_waking_up(p, cpu_of(rq));
1602 }
1603 
1604 /*
1605  * Mark the task runnable and perform wakeup-preemption.
1606  */
1607 static void
1608 ttwu_do_wakeup(struct rq *rq, struct task_struct *p, int wake_flags)
1609 {
1610         check_preempt_curr(rq, p, wake_flags);
1611         p->state = TASK_RUNNING;
1612         trace_sched_wakeup(p);
1613 
1614 #ifdef CONFIG_SMP
1615         if (p->sched_class->task_woken) {
1616                 /*
1617                  * Our task @p is fully woken up and running; so its safe to
1618                  * drop the rq->lock, hereafter rq is only used for statistics.
1619                  */
1620                 lockdep_unpin_lock(&rq->lock);
1621                 p->sched_class->task_woken(rq, p);
1622                 lockdep_pin_lock(&rq->lock);
1623         }
1624 
1625         if (rq->idle_stamp) {
1626                 u64 delta = rq_clock(rq) - rq->idle_stamp;
1627                 u64 max = 2*rq->max_idle_balance_cost;
1628 
1629                 update_avg(&rq->avg_idle, delta);
1630 
1631                 if (rq->avg_idle > max)
1632                         rq->avg_idle = max;
1633 
1634                 rq->idle_stamp = 0;
1635         }
1636 #endif
1637 }
1638 
1639 static void
1640 ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags)
1641 {
1642         lockdep_assert_held(&rq->lock);
1643 
1644 #ifdef CONFIG_SMP
1645         if (p->sched_contributes_to_load)
1646                 rq->nr_uninterruptible--;
1647 #endif
1648 
1649         ttwu_activate(rq, p, ENQUEUE_WAKEUP | ENQUEUE_WAKING);
1650         ttwu_do_wakeup(rq, p, wake_flags);
1651 }
1652 
1653 /*
1654  * Called in case the task @p isn't fully descheduled from its runqueue,
1655  * in this case we must do a remote wakeup. Its a 'light' wakeup though,
1656  * since all we need to do is flip p->state to TASK_RUNNING, since
1657  * the task is still ->on_rq.
1658  */
1659 static int ttwu_remote(struct task_struct *p, int wake_flags)
1660 {
1661         struct rq *rq;
1662         int ret = 0;
1663 
1664         rq = __task_rq_lock(p);
1665         if (task_on_rq_queued(p)) {
1666                 /* check_preempt_curr() may use rq clock */
1667                 update_rq_clock(rq);
1668                 ttwu_do_wakeup(rq, p, wake_flags);
1669                 ret = 1;
1670         }
1671         __task_rq_unlock(rq);
1672 
1673         return ret;
1674 }
1675 
1676 #ifdef CONFIG_SMP
1677 void sched_ttwu_pending(void)
1678 {
1679         struct rq *rq = this_rq();
1680         struct llist_node *llist = llist_del_all(&rq->wake_list);
1681         struct task_struct *p;
1682         unsigned long flags;
1683 
1684         if (!llist)
1685                 return;
1686 
1687         raw_spin_lock_irqsave(&rq->lock, flags);
1688         lockdep_pin_lock(&rq->lock);
1689 
1690         while (llist) {
1691                 p = llist_entry(llist, struct task_struct, wake_entry);
1692                 llist = llist_next(llist);
1693                 ttwu_do_activate(rq, p, 0);
1694         }
1695 
1696         lockdep_unpin_lock(&rq->lock);
1697         raw_spin_unlock_irqrestore(&rq->lock, flags);
1698 }
1699 
1700 void scheduler_ipi(void)
1701 {
1702         /*
1703          * Fold TIF_NEED_RESCHED into the preempt_count; anybody setting
1704          * TIF_NEED_RESCHED remotely (for the first time) will also send
1705          * this IPI.
1706          */
1707         preempt_fold_need_resched();
1708 
1709         if (llist_empty(&this_rq()->wake_list) && !got_nohz_idle_kick())
1710                 return;
1711 
1712         /*
1713          * Not all reschedule IPI handlers call irq_enter/irq_exit, since
1714          * traditionally all their work was done from the interrupt return
1715          * path. Now that we actually do some work, we need to make sure
1716          * we do call them.
1717          *
1718          * Some archs already do call them, luckily irq_enter/exit nest
1719          * properly.
1720          *
1721          * Arguably we should visit all archs and update all handlers,
1722          * however a fair share of IPIs are still resched only so this would
1723          * somewhat pessimize the simple resched case.
1724          */
1725         irq_enter();
1726         sched_ttwu_pending();
1727 
1728         /*
1729          * Check if someone kicked us for doing the nohz idle load balance.
1730          */
1731         if (unlikely(got_nohz_idle_kick())) {
1732                 this_rq()->idle_balance = 1;
1733                 raise_softirq_irqoff(SCHED_SOFTIRQ);
1734         }
1735         irq_exit();
1736 }
1737 
1738 static void ttwu_queue_remote(struct task_struct *p, int cpu)
1739 {
1740         struct rq *rq = cpu_rq(cpu);
1741 
1742         if (llist_add(&p->wake_entry, &cpu_rq(cpu)->wake_list)) {
1743                 if (!set_nr_if_polling(rq->idle))
1744                         smp_send_reschedule(cpu);
1745                 else
1746                         trace_sched_wake_idle_without_ipi(cpu);
1747         }
1748 }
1749 
1750 void wake_up_if_idle(int cpu)
1751 {
1752         struct rq *rq = cpu_rq(cpu);
1753         unsigned long flags;
1754 
1755         rcu_read_lock();
1756 
1757         if (!is_idle_task(rcu_dereference(rq->curr)))
1758                 goto out;
1759 
1760         if (set_nr_if_polling(rq->idle)) {
1761                 trace_sched_wake_idle_without_ipi(cpu);
1762         } else {
1763                 raw_spin_lock_irqsave(&rq->lock, flags);
1764                 if (is_idle_task(rq->curr))
1765                         smp_send_reschedule(cpu);
1766                 /* Else cpu is not in idle, do nothing here */
1767                 raw_spin_unlock_irqrestore(&rq->lock, flags);
1768         }
1769 
1770 out:
1771         rcu_read_unlock();
1772 }
1773 
1774 bool cpus_share_cache(int this_cpu, int that_cpu)
1775 {
1776         return per_cpu(sd_llc_id, this_cpu) == per_cpu(sd_llc_id, that_cpu);
1777 }
1778 #endif /* CONFIG_SMP */
1779 
1780 static void ttwu_queue(struct task_struct *p, int cpu)
1781 {
1782         struct rq *rq = cpu_rq(cpu);
1783 
1784 #if defined(CONFIG_SMP)
1785         if (sched_feat(TTWU_QUEUE) && !cpus_share_cache(smp_processor_id(), cpu)) {
1786                 sched_clock_cpu(cpu); /* sync clocks x-cpu */
1787                 ttwu_queue_remote(p, cpu);
1788                 return;
1789         }
1790 #endif
1791 
1792         raw_spin_lock(&rq->lock);
1793         lockdep_pin_lock(&rq->lock);
1794         ttwu_do_activate(rq, p, 0);
1795         lockdep_unpin_lock(&rq->lock);
1796         raw_spin_unlock(&rq->lock);
1797 }
1798 
1799 /*
1800  * Notes on Program-Order guarantees on SMP systems.
1801  *
1802  *  MIGRATION
1803  *
1804  * The basic program-order guarantee on SMP systems is that when a task [t]
1805  * migrates, all its activity on its old cpu [c0] happens-before any subsequent
1806  * execution on its new cpu [c1].
1807  *
1808  * For migration (of runnable tasks) this is provided by the following means:
1809  *
1810  *  A) UNLOCK of the rq(c0)->lock scheduling out task t
1811  *  B) migration for t is required to synchronize *both* rq(c0)->lock and
1812  *     rq(c1)->lock (if not at the same time, then in that order).
1813  *  C) LOCK of the rq(c1)->lock scheduling in task
1814  *
1815  * Transitivity guarantees that B happens after A and C after B.
1816  * Note: we only require RCpc transitivity.
1817  * Note: the cpu doing B need not be c0 or c1
1818  *
1819  * Example:
1820  *
1821  *   CPU0            CPU1            CPU2
1822  *
1823  *   LOCK rq(0)->lock
1824  *   sched-out X
1825  *   sched-in Y
1826  *   UNLOCK rq(0)->lock
1827  *
1828  *                                   LOCK rq(0)->lock // orders against CPU0
1829  *                                   dequeue X
1830  *                                   UNLOCK rq(0)->lock
1831  *
1832  *                                   LOCK rq(1)->lock
1833  *                                   enqueue X
1834  *                                   UNLOCK rq(1)->lock
1835  *
1836  *                   LOCK rq(1)->lock // orders against CPU2
1837  *                   sched-out Z
1838  *                   sched-in X
1839  *                   UNLOCK rq(1)->lock
1840  *
1841  *
1842  *  BLOCKING -- aka. SLEEP + WAKEUP
1843  *
1844  * For blocking we (obviously) need to provide the same guarantee as for
1845  * migration. However the means are completely different as there is no lock
1846  * chain to provide order. Instead we do:
1847  *
1848  *   1) smp_store_release(X->on_cpu, 0)
1849  *   2) smp_cond_acquire(!X->on_cpu)
1850  *
1851  * Example:
1852  *
1853  *   CPU0 (schedule)  CPU1 (try_to_wake_up) CPU2 (schedule)
1854  *
1855  *   LOCK rq(0)->lock LOCK X->pi_lock
1856  *   dequeue X
1857  *   sched-out X
1858  *   smp_store_release(X->on_cpu, 0);
1859  *
1860  *                    smp_cond_acquire(!X->on_cpu);
1861  *                    X->state = WAKING
1862  *                    set_task_cpu(X,2)
1863  *
1864  *                    LOCK rq(2)->lock
1865  *                    enqueue X
1866  *                    X->state = RUNNING
1867  *                    UNLOCK rq(2)->lock
1868  *
1869  *                                          LOCK rq(2)->lock // orders against CPU1
1870  *                                          sched-out Z
1871  *                                          sched-in X
1872  *                                          UNLOCK rq(2)->lock
1873  *
1874  *                    UNLOCK X->pi_lock
1875  *   UNLOCK rq(0)->lock
1876  *
1877  *
1878  * However; for wakeups there is a second guarantee we must provide, namely we
1879  * must observe the state that lead to our wakeup. That is, not only must our
1880  * task observe its own prior state, it must also observe the stores prior to
1881  * its wakeup.
1882  *
1883  * This means that any means of doing remote wakeups must order the CPU doing
1884  * the wakeup against the CPU the task is going to end up running on. This,
1885  * however, is already required for the regular Program-Order guarantee above,
1886  * since the waking CPU is the one issueing the ACQUIRE (smp_cond_acquire).
1887  *
1888  */
1889 
1890 /**
1891  * try_to_wake_up - wake up a thread
1892  * @p: the thread to be awakened
1893  * @state: the mask of task states that can be woken
1894  * @wake_flags: wake modifier flags (WF_*)
1895  *
1896  * Put it on the run-queue if it's not already there. The "current"
1897  * thread is always on the run-queue (except when the actual
1898  * re-schedule is in progress), and as such you're allowed to do
1899  * the simpler "current->state = TASK_RUNNING" to mark yourself
1900  * runnable without the overhead of this.
1901  *
1902  * Return: %true if @p was woken up, %false if it was already running.
1903  * or @state didn't match @p's state.
1904  */
1905 static int
1906 try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
1907 {
1908         unsigned long flags;
1909         int cpu, success = 0;
1910 
1911         /*
1912          * If we are going to wake up a thread waiting for CONDITION we
1913          * need to ensure that CONDITION=1 done by the caller can not be
1914          * reordered with p->state check below. This pairs with mb() in
1915          * set_current_state() the waiting thread does.
1916          */
1917         smp_mb__before_spinlock();
1918         raw_spin_lock_irqsave(&p->pi_lock, flags);
1919         if (!(p->state & state))
1920                 goto out;
1921 
1922         trace_sched_waking(p);
1923 
1924         success = 1; /* we're going to change ->state */
1925         cpu = task_cpu(p);
1926 
1927         if (p->on_rq && ttwu_remote(p, wake_flags))
1928                 goto stat;
1929 
1930 #ifdef CONFIG_SMP
1931         /*
1932          * Ensure we load p->on_cpu _after_ p->on_rq, otherwise it would be
1933          * possible to, falsely, observe p->on_cpu == 0.
1934          *
1935          * One must be running (->on_cpu == 1) in order to remove oneself
1936          * from the runqueue.
1937          *
1938          *  [S] ->on_cpu = 1;   [L] ->on_rq
1939          *      UNLOCK rq->lock
1940          *                      RMB
1941          *      LOCK   rq->lock
1942          *  [S] ->on_rq = 0;    [L] ->on_cpu
1943          *
1944          * Pairs with the full barrier implied in the UNLOCK+LOCK on rq->lock
1945          * from the consecutive calls to schedule(); the first switching to our
1946          * task, the second putting it to sleep.
1947          */
1948         smp_rmb();
1949 
1950         /*
1951          * If the owning (remote) cpu is still in the middle of schedule() with
1952          * this task as prev, wait until its done referencing the task.
1953          *
1954          * Pairs with the smp_store_release() in finish_lock_switch().
1955          *
1956          * This ensures that tasks getting woken will be fully ordered against
1957          * their previous state and preserve Program Order.
1958          */
1959         smp_cond_acquire(!p->on_cpu);
1960 
1961         p->sched_contributes_to_load = !!task_contributes_to_load(p);
1962         p->state = TASK_WAKING;
1963 
1964         if (p->sched_class->task_waking)
1965                 p->sched_class->task_waking(p);
1966 
1967         cpu = select_task_rq(p, p->wake_cpu, SD_BALANCE_WAKE, wake_flags);
1968         if (task_cpu(p) != cpu) {
1969                 wake_flags |= WF_MIGRATED;
1970                 set_task_cpu(p, cpu);
1971         }
1972 #endif /* CONFIG_SMP */
1973 
1974         ttwu_queue(p, cpu);
1975 stat:
1976         if (schedstat_enabled())
1977                 ttwu_stat(p, cpu, wake_flags);
1978 out:
1979         raw_spin_unlock_irqrestore(&p->pi_lock, flags);
1980 
1981         return success;
1982 }
1983 
1984 /**
1985  * try_to_wake_up_local - try to wake up a local task with rq lock held
1986  * @p: the thread to be awakened
1987  *
1988  * Put @p on the run-queue if it's not already there. The caller must
1989  * ensure that this_rq() is locked, @p is bound to this_rq() and not
1990  * the current task.
1991  */
1992 static void try_to_wake_up_local(struct task_struct *p)
1993 {
1994         struct rq *rq = task_rq(p);
1995 
1996         if (WARN_ON_ONCE(rq != this_rq()) ||
1997             WARN_ON_ONCE(p == current))
1998                 return;
1999 
2000         lockdep_assert_held(&rq->lock);
2001 
2002         if (!raw_spin_trylock(&p->pi_lock)) {
2003                 /*
2004                  * This is OK, because current is on_cpu, which avoids it being
2005                  * picked for load-balance and preemption/IRQs are still
2006                  * disabled avoiding further scheduler activity on it and we've
2007                  * not yet picked a replacement task.
2008                  */
2009                 lockdep_unpin_lock(&rq->lock);
2010                 raw_spin_unlock(&rq->lock);
2011                 raw_spin_lock(&p->pi_lock);
2012                 raw_spin_lock(&rq->lock);
2013                 lockdep_pin_lock(&rq->lock);
2014         }
2015 
2016         if (!(p->state & TASK_NORMAL))
2017                 goto out;
2018 
2019         trace_sched_waking(p);
2020 
2021         if (!task_on_rq_queued(p))
2022                 ttwu_activate(rq, p, ENQUEUE_WAKEUP);
2023 
2024         ttwu_do_wakeup(rq, p, 0);
2025         if (schedstat_enabled())
2026                 ttwu_stat(p, smp_processor_id(), 0);
2027 out:
2028         raw_spin_unlock(&p->pi_lock);
2029 }
2030 
2031 /**
2032  * wake_up_process - Wake up a specific process
2033  * @p: The process to be woken up.
2034  *
2035  * Attempt to wake up the nominated process and move it to the set of runnable
2036  * processes.
2037  *
2038  * Return: 1 if the process was woken up, 0 if it was already running.
2039  *
2040  * It may be assumed that this function implies a write memory barrier before
2041  * changing the task state if and only if any tasks are woken up.
2042  */
2043 int wake_up_process(struct task_struct *p)
2044 {
2045         return try_to_wake_up(p, TASK_NORMAL, 0);
2046 }
2047 EXPORT_SYMBOL(wake_up_process);
2048 
2049 int wake_up_state(struct task_struct *p, unsigned int state)
2050 {
2051         return try_to_wake_up(p, state, 0);
2052 }
2053 
2054 /*
2055  * This function clears the sched_dl_entity static params.
2056  */
2057 void __dl_clear_params(struct task_struct *p)
2058 {
2059         struct sched_dl_entity *dl_se = &p->dl;
2060 
2061         dl_se->dl_runtime = 0;
2062         dl_se->dl_deadline = 0;
2063         dl_se->dl_period = 0;
2064         dl_se->flags = 0;
2065         dl_se->dl_bw = 0;
2066 
2067         dl_se->dl_throttled = 0;
2068         dl_se->dl_yielded = 0;
2069 }
2070 
2071 /*
2072  * Perform scheduler related setup for a newly forked process p.
2073  * p is forked by current.
2074  *
2075  * __sched_fork() is basic setup used by init_idle() too:
2076  */
2077 static void __sched_fork(unsigned long clone_flags, struct task_struct *p)
2078 {
2079         p->on_rq                        = 0;
2080 
2081         p->se.on_rq                     = 0;
2082         p->se.exec_start                = 0;
2083         p->se.sum_exec_runtime          = 0;
2084         p->se.prev_sum_exec_runtime     = 0;
2085         p->se.nr_migrations             = 0;
2086         p->se.vruntime                  = 0;
2087         INIT_LIST_HEAD(&p->se.group_node);
2088 
2089 #ifdef CONFIG_FAIR_GROUP_SCHED
2090         p->se.cfs_rq                    = NULL;
2091 #endif
2092 
2093 #ifdef CONFIG_SCHEDSTATS
2094         /* Even if schedstat is disabled, there should not be garbage */
2095         memset(&p->se.statistics, 0, sizeof(p->se.statistics));
2096 #endif
2097 
2098         RB_CLEAR_NODE(&p->dl.rb_node);
2099         init_dl_task_timer(&p->dl);
2100         __dl_clear_params(p);
2101 
2102         INIT_LIST_HEAD(&p->rt.run_list);
2103         p->rt.timeout           = 0;
2104         p->rt.time_slice        = sched_rr_timeslice;
2105         p->rt.on_rq             = 0;
2106         p->rt.on_list           = 0;
2107 
2108 #ifdef CONFIG_PREEMPT_NOTIFIERS
2109         INIT_HLIST_HEAD(&p->preempt_notifiers);
2110 #endif
2111 
2112 #ifdef CONFIG_NUMA_BALANCING
2113         if (p->mm && atomic_read(&p->mm->mm_users) == 1) {
2114                 p->mm->numa_next_scan = jiffies + msecs_to_jiffies(sysctl_numa_balancing_scan_delay);
2115                 p->mm->numa_scan_seq = 0;
2116         }
2117 
2118         if (clone_flags & CLONE_VM)
2119                 p->numa_preferred_nid = current->numa_preferred_nid;
2120         else
2121                 p->numa_preferred_nid = -1;
2122 
2123         p->node_stamp = 0ULL;
2124         p->numa_scan_seq = p->mm ? p->mm->numa_scan_seq : 0;
2125         p->numa_scan_period = sysctl_numa_balancing_scan_delay;
2126         p->numa_work.next = &p->numa_work;
2127         p->numa_faults = NULL;
2128         p->last_task_numa_placement = 0;
2129         p->last_sum_exec_runtime = 0;
2130 
2131         p->numa_group = NULL;
2132 #endif /* CONFIG_NUMA_BALANCING */
2133 }
2134 
2135 DEFINE_STATIC_KEY_FALSE(sched_numa_balancing);
2136 
2137 #ifdef CONFIG_NUMA_BALANCING
2138 
2139 void set_numabalancing_state(bool enabled)
2140 {
2141         if (enabled)
2142                 static_branch_enable(&sched_numa_balancing);
2143         else
2144                 static_branch_disable(&sched_numa_balancing);
2145 }
2146 
2147 #ifdef CONFIG_PROC_SYSCTL
2148 int sysctl_numa_balancing(struct ctl_table *table, int write,
2149                          void __user *buffer, size_t *lenp, loff_t *ppos)
2150 {
2151         struct ctl_table t;
2152         int err;
2153         int state = static_branch_likely(&sched_numa_balancing);
2154 
2155         if (write && !capable(CAP_SYS_ADMIN))
2156                 return -EPERM;
2157 
2158         t = *table;
2159         t.data = &state;
2160         err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
2161         if (err < 0)
2162                 return err;
2163         if (write)
2164                 set_numabalancing_state(state);
2165         return err;
2166 }
2167 #endif
2168 #endif
2169 
2170 DEFINE_STATIC_KEY_FALSE(sched_schedstats);
2171 
2172 #ifdef CONFIG_SCHEDSTATS
2173 static void set_schedstats(bool enabled)
2174 {
2175         if (enabled)
2176                 static_branch_enable(&sched_schedstats);
2177         else
2178                 static_branch_disable(&sched_schedstats);
2179 }
2180 
2181 void force_schedstat_enabled(void)
2182 {
2183         if (!schedstat_enabled()) {
2184                 pr_info("kernel profiling enabled schedstats, disable via kernel.sched_schedstats.\n");
2185                 static_branch_enable(&sched_schedstats);
2186         }
2187 }
2188 
2189 static int __init setup_schedstats(char *str)
2190 {
2191         int ret = 0;
2192         if (!str)
2193                 goto out;
2194 
2195         if (!strcmp(str, "enable")) {
2196                 set_schedstats(true);
2197                 ret = 1;
2198         } else if (!strcmp(str, "disable")) {
2199                 set_schedstats(false);
2200                 ret = 1;
2201         }
2202 out:
2203         if (!ret)
2204                 pr_warn("Unable to parse schedstats=\n");
2205 
2206         return ret;
2207 }
2208 __setup("schedstats=", setup_schedstats);
2209 
2210 #ifdef CONFIG_PROC_SYSCTL
2211 int sysctl_schedstats(struct ctl_table *table, int write,
2212                          void __user *buffer, size_t *lenp, loff_t *ppos)
2213 {
2214         struct ctl_table t;
2215         int err;
2216         int state = static_branch_likely(&sched_schedstats);
2217 
2218         if (write && !capable(CAP_SYS_ADMIN))
2219                 return -EPERM;
2220 
2221         t = *table;
2222         t.data = &state;
2223         err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
2224         if (err < 0)
2225                 return err;
2226         if (write)
2227                 set_schedstats(state);
2228         return err;
2229 }
2230 #endif
2231 #endif
2232 
2233 /*
2234  * fork()/clone()-time setup:
2235  */
2236 int sched_fork(unsigned long clone_flags, struct task_struct *p)
2237 {
2238         unsigned long flags;
2239         int cpu = get_cpu();
2240 
2241         __sched_fork(clone_flags, p);
2242         /*
2243          * We mark the process as running here. This guarantees that
2244          * nobody will actually run it, and a signal or other external
2245          * event cannot wake it up and insert it on the runqueue either.
2246          */
2247         p->state = TASK_RUNNING;
2248 
2249         /*
2250          * Make sure we do not leak PI boosting priority to the child.
2251          */
2252         p->prio = current->normal_prio;
2253 
2254         /*
2255          * Revert to default priority/policy on fork if requested.
2256          */
2257         if (unlikely(p->sched_reset_on_fork)) {
2258                 if (task_has_dl_policy(p) || task_has_rt_policy(p)) {
2259                         p->policy = SCHED_NORMAL;
2260                         p->static_prio = NICE_TO_PRIO(0);
2261                         p->rt_priority = 0;
2262                 } else if (PRIO_TO_NICE(p->static_prio) < 0)
2263                         p->static_prio = NICE_TO_PRIO(0);
2264 
2265                 p->prio = p->normal_prio = __normal_prio(p);
2266                 set_load_weight(p);
2267 
2268                 /*
2269                  * We don't need the reset flag anymore after the fork. It has
2270                  * fulfilled its duty:
2271                  */
2272                 p->sched_reset_on_fork = 0;
2273         }
2274 
2275         if (dl_prio(p->prio)) {
2276                 put_cpu();
2277                 return -EAGAIN;
2278         } else if (rt_prio(p->prio)) {
2279                 p->sched_class = &rt_sched_class;
2280         } else {
2281                 p->sched_class = &fair_sched_class;
2282         }
2283 
2284         if (p->sched_class->task_fork)
2285                 p->sched_class->task_fork(p);
2286 
2287         /*
2288          * The child is not yet in the pid-hash so no cgroup attach races,
2289          * and the cgroup is pinned to this child due to cgroup_fork()
2290          * is ran before sched_fork().
2291          *
2292          * Silence PROVE_RCU.
2293          */
2294         raw_spin_lock_irqsave(&p->pi_lock, flags);
2295         set_task_cpu(p, cpu);
2296         raw_spin_unlock_irqrestore(&p->pi_lock, flags);
2297 
2298 #ifdef CONFIG_SCHED_INFO
2299         if (likely(sched_info_on()))
2300                 memset(&p->sched_info, 0, sizeof(p->sched_info));
2301 #endif
2302 #if defined(CONFIG_SMP)
2303         p->on_cpu = 0;
2304 #endif
2305         init_task_preempt_count(p);
2306 #ifdef CONFIG_SMP
2307         plist_node_init(&p->pushable_tasks, MAX_PRIO);
2308         RB_CLEAR_NODE(&p->pushable_dl_tasks);
2309 #endif
2310 
2311         put_cpu();
2312         return 0;
2313 }
2314 
2315 unsigned long to_ratio(u64 period, u64 runtime)
2316 {
2317         if (runtime == RUNTIME_INF)
2318                 return 1ULL << 20;
2319 
2320         /*
2321          * Doing this here saves a lot of checks in all
2322          * the calling paths, and returning zero seems
2323          * safe for them anyway.
2324          */
2325         if (period == 0)
2326                 return 0;
2327 
2328         return div64_u64(runtime << 20, period);
2329 }
2330 
2331 #ifdef CONFIG_SMP
2332 inline struct dl_bw *dl_bw_of(int i)
2333 {
2334         RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(),
2335                          "sched RCU must be held");
2336         return &cpu_rq(i)->rd->dl_bw;
2337 }
2338 
2339 static inline int dl_bw_cpus(int i)
2340 {
2341         struct root_domain *rd = cpu_rq(i)->rd;
2342         int cpus = 0;
2343 
2344         RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(),
2345                          "sched RCU must be held");
2346         for_each_cpu_and(i, rd->span, cpu_active_mask)
2347                 cpus++;
2348 
2349         return cpus;
2350 }
2351 #else
2352 inline struct dl_bw *dl_bw_of(int i)
2353 {
2354         return &cpu_rq(i)->dl.dl_bw;
2355 }
2356 
2357 static inline int dl_bw_cpus(int i)
2358 {
2359         return 1;
2360 }
2361 #endif
2362 
2363 /*
2364  * We must be sure that accepting a new task (or allowing changing the
2365  * parameters of an existing one) is consistent with the bandwidth
2366  * constraints. If yes, this function also accordingly updates the currently
2367  * allocated bandwidth to reflect the new situation.
2368  *
2369  * This function is called while holding p's rq->lock.
2370  *
2371  * XXX we should delay bw change until the task's 0-lag point, see
2372  * __setparam_dl().
2373  */
2374 static int dl_overflow(struct task_struct *p, int policy,
2375                        const struct sched_attr *attr)
2376 {
2377 
2378         struct dl_bw *dl_b = dl_bw_of(task_cpu(p));
2379         u64 period = attr->sched_period ?: attr->sched_deadline;
2380         u64 runtime = attr->sched_runtime;
2381         u64 new_bw = dl_policy(policy) ? to_ratio(period, runtime) : 0;
2382         int cpus, err = -1;
2383 
2384         if (new_bw == p->dl.dl_bw)
2385                 return 0;
2386 
2387         /*
2388          * Either if a task, enters, leave, or stays -deadline but changes
2389          * its parameters, we may need to update accordingly the total
2390          * allocated bandwidth of the container.
2391          */
2392         raw_spin_lock(&dl_b->lock);
2393         cpus = dl_bw_cpus(task_cpu(p));
2394         if (dl_policy(policy) && !task_has_dl_policy(p) &&
2395             !__dl_overflow(dl_b, cpus, 0, new_bw)) {
2396                 __dl_add(dl_b, new_bw);
2397                 err = 0;
2398         } else if (dl_policy(policy) && task_has_dl_policy(p) &&
2399                    !__dl_overflow(dl_b, cpus, p->dl.dl_bw, new_bw)) {
2400                 __dl_clear(dl_b, p->dl.dl_bw);
2401                 __dl_add(dl_b, new_bw);
2402                 err = 0;
2403         } else if (!dl_policy(policy) && task_has_dl_policy(p)) {
2404                 __dl_clear(dl_b, p->dl.dl_bw);
2405                 err = 0;
2406         }
2407         raw_spin_unlock(&dl_b->lock);
2408 
2409         return err;
2410 }
2411 
2412 extern void init_dl_bw(struct dl_bw *dl_b);
2413 
2414 /*
2415  * wake_up_new_task - wake up a newly created task for the first time.
2416  *
2417  * This function will do some initial scheduler statistics housekeeping
2418  * that must be done for every newly created context, then puts the task
2419  * on the runqueue and wakes it.
2420  */
2421 void wake_up_new_task(struct task_struct *p)
2422 {
2423         unsigned long flags;
2424         struct rq *rq;
2425 
2426         raw_spin_lock_irqsave(&p->pi_lock, flags);
2427         /* Initialize new task's runnable average */
2428         init_entity_runnable_average(&p->se);
2429 #ifdef CONFIG_SMP
2430         /*
2431          * Fork balancing, do it here and not earlier because:
2432          *  - cpus_allowed can change in the fork path
2433          *  - any previously selected cpu might disappear through hotplug
2434          */
2435         set_task_cpu(p, select_task_rq(p, task_cpu(p), SD_BALANCE_FORK, 0));
2436 #endif
2437 
2438         rq = __task_rq_lock(p);
2439         activate_task(rq, p, 0);
2440         p->on_rq = TASK_ON_RQ_QUEUED;
2441         trace_sched_wakeup_new(p);
2442         check_preempt_curr(rq, p, WF_FORK);
2443 #ifdef CONFIG_SMP
2444         if (p->sched_class->task_woken) {
2445                 /*
2446                  * Nothing relies on rq->lock after this, so its fine to
2447                  * drop it.
2448                  */
2449                 lockdep_unpin_lock(&rq->lock);
2450                 p->sched_class->task_woken(rq, p);
2451                 lockdep_pin_lock(&rq->lock);
2452         }
2453 #endif
2454         task_rq_unlock(rq, p, &flags);
2455 }
2456 
2457 #ifdef CONFIG_PREEMPT_NOTIFIERS
2458 
2459 static struct static_key preempt_notifier_key = STATIC_KEY_INIT_FALSE;
2460 
2461 void preempt_notifier_inc(void)
2462 {
2463         static_key_slow_inc(&preempt_notifier_key);
2464 }
2465 EXPORT_SYMBOL_GPL(preempt_notifier_inc);
2466 
2467 void preempt_notifier_dec(void)
2468 {
2469         static_key_slow_dec(&preempt_notifier_key);
2470 }
2471 EXPORT_SYMBOL_GPL(preempt_notifier_dec);
2472 
2473 /**
2474  * preempt_notifier_register - tell me when current is being preempted & rescheduled
2475  * @notifier: notifier struct to register
2476  */
2477 void preempt_notifier_register(struct preempt_notifier *notifier)
2478 {
2479         if (!static_key_false(&preempt_notifier_key))
2480                 WARN(1, "registering preempt_notifier while notifiers disabled\n");
2481 
2482         hlist_add_head(&notifier->link, &current->preempt_notifiers);
2483 }
2484 EXPORT_SYMBOL_GPL(preempt_notifier_register);
2485 
2486 /**
2487  * preempt_notifier_unregister - no longer interested in preemption notifications
2488  * @notifier: notifier struct to unregister
2489  *
2490  * This is *not* safe to call from within a preemption notifier.
2491  */
2492 void preempt_notifier_unregister(struct preempt_notifier *notifier)
2493 {
2494         hlist_del(&notifier->link);
2495 }
2496 EXPORT_SYMBOL_GPL(preempt_notifier_unregister);
2497 
2498 static void __fire_sched_in_preempt_notifiers(struct task_struct *curr)
2499 {
2500         struct preempt_notifier *notifier;
2501 
2502         hlist_for_each_entry(notifier, &curr->preempt_notifiers, link)
2503                 notifier->ops->sched_in(notifier, raw_smp_processor_id());
2504 }
2505 
2506 static __always_inline void fire_sched_in_preempt_notifiers(struct task_struct *curr)
2507 {
2508         if (static_key_false(&preempt_notifier_key))
2509                 __fire_sched_in_preempt_notifiers(curr);
2510 }
2511 
2512 static void
2513 __fire_sched_out_preempt_notifiers(struct task_struct *curr,
2514                                    struct task_struct *next)
2515 {
2516         struct preempt_notifier *notifier;
2517 
2518         hlist_for_each_entry(notifier, &curr->preempt_notifiers, link)
2519                 notifier->ops->sched_out(notifier, next);
2520 }
2521 
2522 static __always_inline void
2523 fire_sched_out_preempt_notifiers(struct task_struct *curr,
2524                                  struct task_struct *next)
2525 {
2526         if (static_key_false(&preempt_notifier_key))
2527                 __fire_sched_out_preempt_notifiers(curr, next);
2528 }
2529 
2530 #else /* !CONFIG_PREEMPT_NOTIFIERS */
2531 
2532 static inline void fire_sched_in_preempt_notifiers(struct task_struct *curr)
2533 {
2534 }
2535 
2536 static inline void
2537 fire_sched_out_preempt_notifiers(struct task_struct *curr,
2538                                  struct task_struct *next)
2539 {
2540 }
2541 
2542 #endif /* CONFIG_PREEMPT_NOTIFIERS */
2543 
2544 /**
2545  * prepare_task_switch - prepare to switch tasks
2546  * @rq: the runqueue preparing to switch
2547  * @prev: the current task that is being switched out
2548  * @next: the task we are going to switch to.
2549  *
2550  * This is called with the rq lock held and interrupts off. It must
2551  * be paired with a subsequent finish_task_switch after the context
2552  * switch.
2553  *
2554  * prepare_task_switch sets up locking and calls architecture specific
2555  * hooks.
2556  */
2557 static inline void
2558 prepare_task_switch(struct rq *rq, struct task_struct *prev,
2559                     struct task_struct *next)
2560 {
2561         sched_info_switch(rq, prev, next);
2562         perf_event_task_sched_out(prev, next);
2563         fire_sched_out_preempt_notifiers(prev, next);
2564         prepare_lock_switch(rq, next);
2565         prepare_arch_switch(next);
2566 }
2567 
2568 /**
2569  * finish_task_switch - clean up after a task-switch
2570  * @prev: the thread we just switched away from.
2571  *
2572  * finish_task_switch must be called after the context switch, paired
2573  * with a prepare_task_switch call before the context switch.
2574  * finish_task_switch will reconcile locking set up by prepare_task_switch,
2575  * and do any other architecture-specific cleanup actions.
2576  *
2577  * Note that we may have delayed dropping an mm in context_switch(). If
2578  * so, we finish that here outside of the runqueue lock. (Doing it
2579  * with the lock held can cause deadlocks; see schedule() for
2580  * details.)
2581  *
2582  * The context switch have flipped the stack from under us and restored the
2583  * local variables which were saved when this task called schedule() in the
2584  * past. prev == current is still correct but we need to recalculate this_rq
2585  * because prev may have moved to another CPU.
2586  */
2587 static struct rq *finish_task_switch(struct task_struct *prev)
2588         __releases(rq->lock)
2589 {
2590         struct rq *rq = this_rq();
2591         struct mm_struct *mm = rq->prev_mm;
2592         long prev_state;
2593 
2594         /*
2595          * The previous task will have left us with a preempt_count of 2
2596          * because it left us after:
2597          *
2598          *      schedule()
2599          *        preempt_disable();                    // 1
2600          *        __schedule()
2601          *          raw_spin_lock_irq(&rq->lock)        // 2
2602          *
2603          * Also, see FORK_PREEMPT_COUNT.
2604          */
2605         if (WARN_ONCE(preempt_count() != 2*PREEMPT_DISABLE_OFFSET,
2606                       "corrupted preempt_count: %s/%d/0x%x\n",
2607                       current->comm, current->pid, preempt_count()))
2608                 preempt_count_set(FORK_PREEMPT_COUNT);
2609 
2610         rq->prev_mm = NULL;
2611 
2612         /*
2613          * A task struct has one reference for the use as "current".
2614          * If a task dies, then it sets TASK_DEAD in tsk->state and calls
2615          * schedule one last time. The schedule call will never return, and
2616          * the scheduled task must drop that reference.
2617          *
2618          * We must observe prev->state before clearing prev->on_cpu (in
2619          * finish_lock_switch), otherwise a concurrent wakeup can get prev
2620          * running on another CPU and we could rave with its RUNNING -> DEAD
2621          * transition, resulting in a double drop.
2622          */
2623         prev_state = prev->state;
2624         vtime_task_switch(prev);
2625         perf_event_task_sched_in(prev, current);
2626         finish_lock_switch(rq, prev);
2627         finish_arch_post_lock_switch();
2628 
2629         fire_sched_in_preempt_notifiers(current);
2630         if (mm)
2631                 mmdrop(mm);
2632         if (unlikely(prev_state == TASK_DEAD)) {
2633                 if (prev->sched_class->task_dead)
2634                         prev->sched_class->task_dead(prev);
2635 
2636                 /*
2637                  * Remove function-return probe instances associated with this
2638                  * task and put them back on the free list.
2639                  */
2640                 kprobe_flush_task(prev);
2641                 put_task_struct(prev);
2642         }
2643 
2644         tick_nohz_task_switch();
2645         return rq;
2646 }
2647 
2648 #ifdef CONFIG_SMP
2649 
2650 /* rq->lock is NOT held, but preemption is disabled */
2651 static void __balance_callback(struct rq *rq)
2652 {
2653         struct callback_head *head, *next;
2654         void (*func)(struct rq *rq);
2655         unsigned long flags;
2656 
2657         raw_spin_lock_irqsave(&rq->lock, flags);
2658         head = rq->balance_callback;
2659         rq->balance_callback = NULL;
2660         while (head) {
2661                 func = (void (*)(struct rq *))head->func;
2662                 next = head->next;
2663                 head->next = NULL;
2664                 head = next;
2665 
2666                 func(rq);
2667         }
2668         raw_spin_unlock_irqrestore(&rq->lock, flags);
2669 }
2670 
2671 static inline void balance_callback(struct rq *rq)
2672 {
2673         if (unlikely(rq->balance_callback))
2674                 __balance_callback(rq);
2675 }
2676 
2677 #else
2678 
2679 static inline void balance_callback(struct rq *rq)
2680 {
2681 }
2682 
2683 #endif
2684 
2685 /**
2686  * schedule_tail - first thing a freshly forked thread must call.
2687  * @prev: the thread we just switched away from.
2688  */
2689 asmlinkage __visible void schedule_tail(struct task_struct *prev)
2690         __releases(rq->lock)
2691 {
2692         struct rq *rq;
2693 
2694         /*
2695          * New tasks start with FORK_PREEMPT_COUNT, see there and
2696          * finish_task_switch() for details.
2697          *
2698          * finish_task_switch() will drop rq->lock() and lower preempt_count
2699          * and the preempt_enable() will end up enabling preemption (on
2700          * PREEMPT_COUNT kernels).
2701          */
2702 
2703         rq = finish_task_switch(prev);
2704         balance_callback(rq);
2705         preempt_enable();
2706 
2707         if (current->set_child_tid)
2708                 put_user(task_pid_vnr(current), current->set_child_tid);
2709 }
2710 
2711 /*
2712  * context_switch - switch to the new MM and the new thread's register state.
2713  */
2714 static __always_inline struct rq *
2715 context_switch(struct rq *rq, struct task_struct *prev,
2716                struct task_struct *next)
2717 {
2718         struct mm_struct *mm, *oldmm;
2719 
2720         prepare_task_switch(rq, prev, next);
2721 
2722         mm = next->mm;
2723         oldmm = prev->active_mm;
2724         /*
2725          * For paravirt, this is coupled with an exit in switch_to to
2726          * combine the page table reload and the switch backend into
2727          * one hypercall.
2728          */
2729         arch_start_context_switch(prev);
2730 
2731         if (!mm) {
2732                 next->active_mm = oldmm;
2733                 atomic_inc(&oldmm->mm_count);
2734                 enter_lazy_tlb(oldmm, next);
2735         } else
2736                 switch_mm(oldmm, mm, next);
2737 
2738         if (!prev->mm) {
2739                 prev->active_mm = NULL;
2740                 rq->prev_mm = oldmm;
2741         }
2742         /*
2743          * Since the runqueue lock will be released by the next
2744          * task (which is an invalid locking op but in the case
2745          * of the scheduler it's an obvious special-case), so we
2746          * do an early lockdep release here:
2747          */
2748         lockdep_unpin_lock(&rq->lock);
2749         spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
2750 
2751         /* Here we just switch the register state and the stack. */
2752         switch_to(prev, next, prev);
2753         barrier();
2754 
2755         return finish_task_switch(prev);
2756 }
2757 
2758 /*
2759  * nr_running and nr_context_switches:
2760  *
2761  * externally visible scheduler statistics: current number of runnable
2762  * threads, total number of context switches performed since bootup.
2763  */
2764 unsigned long nr_running(void)
2765 {
2766         unsigned long i, sum = 0;
2767 
2768         for_each_online_cpu(i)
2769                 sum += cpu_rq(i)->nr_running;
2770 
2771         return sum;
2772 }
2773 
2774 /*
2775  * Check if only the current task is running on the cpu.
2776  *
2777  * Caution: this function does not check that the caller has disabled
2778  * preemption, thus the result might have a time-of-check-to-time-of-use
2779  * race.  The caller is responsible to use it correctly, for example:
2780  *
2781  * - from a non-preemptable section (of course)
2782  *
2783  * - from a thread that is bound to a single CPU
2784  *
2785  * - in a loop with very short iterations (e.g. a polling loop)
2786  */
2787 bool single_task_running(void)
2788 {
2789         return raw_rq()->nr_running == 1;
2790 }
2791 EXPORT_SYMBOL(single_task_running);
2792 
2793 unsigned long long nr_context_switches(void)
2794 {
2795         int i;
2796         unsigned long long sum = 0;
2797 
2798         for_each_possible_cpu(i)
2799                 sum += cpu_rq(i)->nr_switches;
2800 
2801         return sum;
2802 }
2803 
2804 unsigned long nr_iowait(void)
2805 {
2806         unsigned long i, sum = 0;
2807 
2808         for_each_possible_cpu(i)
2809                 sum += atomic_read(&cpu_rq(i)->nr_iowait);
2810 
2811         return sum;
2812 }
2813 
2814 unsigned long nr_iowait_cpu(int cpu)
2815 {
2816         struct rq *this = cpu_rq(cpu);
2817         return atomic_read(&this->nr_iowait);
2818 }
2819 
2820 void get_iowait_load(unsigned long *nr_waiters, unsigned long *load)
2821 {
2822         struct rq *rq = this_rq();
2823         *nr_waiters = atomic_read(&rq->nr_iowait);
2824         *load = rq->load.weight;
2825 }
2826 
2827 #ifdef CONFIG_SMP
2828 
2829 /*
2830  * sched_exec - execve() is a valuable balancing opportunity, because at
2831  * this point the task has the smallest effective memory and cache footprint.
2832  */
2833 void sched_exec(void)
2834 {
2835         struct task_struct *p = current;
2836         unsigned long flags;
2837         int dest_cpu;
2838 
2839         raw_spin_lock_irqsave(&p->pi_lock, flags);
2840         dest_cpu = p->sched_class->select_task_rq(p, task_cpu(p), SD_BALANCE_EXEC, 0);
2841         if (dest_cpu == smp_processor_id())
2842                 goto unlock;
2843 
2844         if (likely(cpu_active(dest_cpu))) {
2845                 struct migration_arg arg = { p, dest_cpu };
2846 
2847                 raw_spin_unlock_irqrestore(&p->pi_lock, flags);
2848                 stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg);
2849                 return;
2850         }
2851 unlock:
2852         raw_spin_unlock_irqrestore(&p->pi_lock, flags);
2853 }
2854 
2855 #endif
2856 
2857 DEFINE_PER_CPU(struct kernel_stat, kstat);
2858 DEFINE_PER_CPU(struct kernel_cpustat, kernel_cpustat);
2859 
2860 EXPORT_PER_CPU_SYMBOL(kstat);
2861 EXPORT_PER_CPU_SYMBOL(kernel_cpustat);
2862 
2863 /*
2864  * Return accounted runtime for the task.
2865  * In case the task is currently running, return the runtime plus current's
2866  * pending runtime that have not been accounted yet.
2867  */
2868 unsigned long long task_sched_runtime(struct task_struct *p)
2869 {
2870         unsigned long flags;
2871         struct rq *rq;
2872         u64 ns;
2873 
2874 #if defined(CONFIG_64BIT) && defined(CONFIG_SMP)
2875         /*
2876          * 64-bit doesn't need locks to atomically read a 64bit value.
2877          * So we have a optimization chance when the task's delta_exec is 0.
2878          * Reading ->on_cpu is racy, but this is ok.
2879          *
2880          * If we race with it leaving cpu, we'll take a lock. So we're correct.
2881          * If we race with it entering cpu, unaccounted time is 0. This is
2882          * indistinguishable from the read occurring a few cycles earlier.
2883          * If we see ->on_cpu without ->on_rq, the task is leaving, and has
2884          * been accounted, so we're correct here as well.
2885          */
2886         if (!p->on_cpu || !task_on_rq_queued(p))
2887                 return p->se.sum_exec_runtime;
2888 #endif
2889 
2890         rq = task_rq_lock(p, &flags);
2891         /*
2892          * Must be ->curr _and_ ->on_rq.  If dequeued, we would
2893          * project cycles that may never be accounted to this
2894          * thread, breaking clock_gettime().
2895          */
2896         if (task_current(rq, p) && task_on_rq_queued(p)) {
2897                 update_rq_clock(rq);
2898                 p->sched_class->update_curr(rq);
2899         }
2900         ns = p->se.sum_exec_runtime;
2901         task_rq_unlock(rq, p, &flags);
2902 
2903         return ns;
2904 }
2905 
2906 /*
2907  * This function gets called by the timer code, with HZ frequency.
2908  * We call it with interrupts disabled.
2909  */
2910 void scheduler_tick(void)
2911 {
2912         int cpu = smp_processor_id();
2913         struct rq *rq = cpu_rq(cpu);
2914         struct task_struct *curr = rq->curr;
2915 
2916         sched_clock_tick();
2917 
2918         raw_spin_lock(&rq->lock);
2919         update_rq_clock(rq);
2920         curr->sched_class->task_tick(rq, curr, 0);
2921         update_cpu_load_active(rq);
2922         calc_global_load_tick(rq);
2923         raw_spin_unlock(&rq->lock);
2924 
2925         perf_event_task_tick();
2926 
2927 #ifdef CONFIG_SMP
2928         rq->idle_balance = idle_cpu(cpu);
2929         trigger_load_balance(rq);
2930 #endif
2931         rq_last_tick_reset(rq);
2932 }
2933 
2934 #ifdef CONFIG_NO_HZ_FULL
2935 /**
2936  * scheduler_tick_max_deferment
2937  *
2938  * Keep at least one tick per second when a single
2939  * active task is running because the scheduler doesn't
2940  * yet completely support full dynticks environment.
2941  *
2942  * This makes sure that uptime, CFS vruntime, load
2943  * balancing, etc... continue to move forward, even
2944  * with a very low granularity.
2945  *
2946  * Return: Maximum deferment in nanoseconds.
2947  */
2948 u64 scheduler_tick_max_deferment(void)
2949 {
2950         struct rq *rq = this_rq();
2951         unsigned long next, now = READ_ONCE(jiffies);
2952 
2953         next = rq->last_sched_tick + HZ;
2954 
2955         if (time_before_eq(next, now))
2956                 return 0;
2957 
2958         return jiffies_to_nsecs(next - now);
2959 }
2960 #endif
2961 
2962 #if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \
2963                                 defined(CONFIG_PREEMPT_TRACER))
2964 
2965 void preempt_count_add(int val)
2966 {
2967 #ifdef CONFIG_DEBUG_PREEMPT
2968         /*
2969          * Underflow?
2970          */
2971         if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
2972                 return;
2973 #endif
2974         __preempt_count_add(val);
2975 #ifdef CONFIG_DEBUG_PREEMPT
2976         /*
2977          * Spinlock count overflowing soon?
2978          */
2979         DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >=
2980                                 PREEMPT_MASK - 10);
2981 #endif
2982         if (preempt_count() == val) {
2983                 unsigned long ip = get_lock_parent_ip();
2984 #ifdef CONFIG_DEBUG_PREEMPT
2985                 current->preempt_disable_ip = ip;
2986 #endif
2987                 trace_preempt_off(CALLER_ADDR0, ip);
2988         }
2989 }
2990 EXPORT_SYMBOL(preempt_count_add);
2991 NOKPROBE_SYMBOL(preempt_count_add);
2992 
2993 void preempt_count_sub(int val)
2994 {
2995 #ifdef CONFIG_DEBUG_PREEMPT
2996         /*
2997          * Underflow?
2998          */
2999         if (DEBUG_LOCKS_WARN_ON(val > preempt_count()))
3000                 return;
3001         /*
3002          * Is the spinlock portion underflowing?
3003          */
3004         if (DEBUG_LOCKS_WARN_ON((val < PREEMPT_MASK) &&
3005                         !(preempt_count() & PREEMPT_MASK)))
3006                 return;
3007 #endif
3008 
3009         if (preempt_count() == val)
3010                 trace_preempt_on(CALLER_ADDR0, get_lock_parent_ip());
3011         __preempt_count_sub(val);
3012 }
3013 EXPORT_SYMBOL(preempt_count_sub);
3014 NOKPROBE_SYMBOL(preempt_count_sub);
3015 
3016 #endif
3017 
3018 /*
3019  * Print scheduling while atomic bug:
3020  */
3021 static noinline void __schedule_bug(struct task_struct *prev)
3022 {
3023         if (oops_in_progress)
3024                 return;
3025 
3026         printk(KERN_ERR "BUG: scheduling while atomic: %s/%d/0x%08x\n",
3027                 prev->comm, prev->pid, preempt_count());
3028 
3029         debug_show_held_locks(prev);
3030         print_modules();
3031         if (irqs_disabled())
3032                 print_irqtrace_events(prev);
3033 #ifdef CONFIG_DEBUG_PREEMPT
3034         if (in_atomic_preempt_off()) {
3035                 pr_err("Preemption disabled at:");
3036                 print_ip_sym(current->preempt_disable_ip);
3037                 pr_cont("\n");
3038         }
3039 #endif
3040         dump_stack();
3041         add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
3042 }
3043 
3044 /*
3045  * Various schedule()-time debugging checks and statistics:
3046  */
3047 static inline void schedule_debug(struct task_struct *prev)
3048 {
3049 #ifdef CONFIG_SCHED_STACK_END_CHECK
3050         BUG_ON(task_stack_end_corrupted(prev));
3051 #endif
3052 
3053         if (unlikely(in_atomic_preempt_off())) {
3054                 __schedule_bug(prev);
3055                 preempt_count_set(PREEMPT_DISABLED);
3056         }
3057         rcu_sleep_check();
3058 
3059         profile_hit(SCHED_PROFILING, __builtin_return_address(0));
3060 
3061         schedstat_inc(this_rq(), sched_count);
3062 }
3063 
3064 /*
3065  * Pick up the highest-prio task:
3066  */
3067 static inline struct task_struct *
3068 pick_next_task(struct rq *rq, struct task_struct *prev)
3069 {
3070         const struct sched_class *class = &fair_sched_class;
3071         struct task_struct *p;
3072 
3073         /*
3074          * Optimization: we know that if all tasks are in
3075          * the fair class we can call that function directly:
3076          */
3077         if (likely(prev->sched_class == class &&
3078                    rq->nr_running == rq->cfs.h_nr_running)) {
3079                 p = fair_sched_class.pick_next_task(rq, prev);
3080                 if (unlikely(p == RETRY_TASK))
3081                         goto again;
3082 
3083                 /* assumes fair_sched_class->next == idle_sched_class */
3084                 if (unlikely(!p))
3085                         p = idle_sched_class.pick_next_task(rq, prev);
3086 
3087                 return p;
3088         }
3089 
3090 again:
3091         for_each_class(class) {
3092                 p = class->pick_next_task(rq, prev);
3093                 if (p) {
3094                         if (unlikely(p == RETRY_TASK))
3095                                 goto again;
3096                         return p;
3097                 }
3098         }
3099 
3100         BUG(); /* the idle class will always have a runnable task */
3101 }
3102 
3103 /*
3104  * __schedule() is the main scheduler function.
3105  *
3106  * The main means of driving the scheduler and thus entering this function are:
3107  *
3108  *   1. Explicit blocking: mutex, semaphore, waitqueue, etc.
3109  *
3110  *   2. TIF_NEED_RESCHED flag is checked on interrupt and userspace return
3111  *      paths. For example, see arch/x86/entry_64.S.
3112  *
3113  *      To drive preemption between tasks, the scheduler sets the flag in timer
3114  *      interrupt handler scheduler_tick().
3115  *
3116  *   3. Wakeups don't really cause entry into schedule(). They add a
3117  *      task to the run-queue and that's it.
3118  *
3119  *      Now, if the new task added to the run-queue preempts the current
3120  *      task, then the wakeup sets TIF_NEED_RESCHED and schedule() gets
3121  *      called on the nearest possible occasion:
3122  *
3123  *       - If the kernel is preemptible (CONFIG_PREEMPT=y):
3124  *
3125  *         - in syscall or exception context, at the next outmost
3126  *           preempt_enable(). (this might be as soon as the wake_up()'s
3127  *           spin_unlock()!)
3128  *
3129  *         - in IRQ context, return from interrupt-handler to
3130  *           preemptible context
3131  *
3132  *       - If the kernel is not preemptible (CONFIG_PREEMPT is not set)
3133  *         then at the next:
3134  *
3135  *          - cond_resched() call
3136  *          - explicit schedule() call
3137  *          - return from syscall or exception to user-space
3138  *          - return from interrupt-handler to user-space
3139  *
3140  * WARNING: must be called with preemption disabled!
3141  */
3142 static void __sched notrace __schedule(bool preempt)
3143 {
3144         struct task_struct *prev, *next;
3145         unsigned long *switch_count;
3146         struct rq *rq;
3147         int cpu;
3148 
3149         cpu = smp_processor_id();
3150         rq = cpu_rq(cpu);
3151         prev = rq->curr;
3152 
3153         /*
3154          * do_exit() calls schedule() with preemption disabled as an exception;
3155          * however we must fix that up, otherwise the next task will see an
3156          * inconsistent (higher) preempt count.
3157          *
3158          * It also avoids the below schedule_debug() test from complaining
3159          * about this.
3160          */
3161         if (unlikely(prev->state == TASK_DEAD))
3162                 preempt_enable_no_resched_notrace();
3163 
3164         schedule_debug(prev);
3165 
3166         if (sched_feat(HRTICK))
3167                 hrtick_clear(rq);
3168 
3169         local_irq_disable();
3170         rcu_note_context_switch();
3171 
3172         /*
3173          * Make sure that signal_pending_state()->signal_pending() below
3174          * can't be reordered with __set_current_state(TASK_INTERRUPTIBLE)
3175          * done by the caller to avoid the race with signal_wake_up().
3176          */
3177         smp_mb__before_spinlock();
3178         raw_spin_lock(&rq->lock);
3179         lockdep_pin_lock(&rq->lock);
3180 
3181         rq->clock_skip_update <<= 1; /* promote REQ to ACT */
3182 
3183         switch_count = &prev->nivcsw;
3184         if (!preempt && prev->state) {
3185                 if (unlikely(signal_pending_state(prev->state, prev))) {
3186                         prev->state = TASK_RUNNING;
3187                 } else {
3188                         deactivate_task(rq, prev, DEQUEUE_SLEEP);
3189                         prev->on_rq = 0;
3190 
3191                         /*
3192                          * If a worker went to sleep, notify and ask workqueue
3193                          * whether it wants to wake up a task to maintain
3194                          * concurrency.
3195                          */
3196                         if (prev->flags & PF_WQ_WORKER) {
3197                                 struct task_struct *to_wakeup;
3198 
3199                                 to_wakeup = wq_worker_sleeping(prev);
3200                                 if (to_wakeup)
3201                                         try_to_wake_up_local(to_wakeup);
3202                         }
3203                 }
3204                 switch_count = &prev->nvcsw;
3205         }
3206 
3207         if (task_on_rq_queued(prev))
3208                 update_rq_clock(rq);
3209 
3210         next = pick_next_task(rq, prev);
3211         clear_tsk_need_resched(prev);
3212         clear_preempt_need_resched();
3213         rq->clock_skip_update = 0;
3214 
3215         if (likely(prev != next)) {
3216                 rq->nr_switches++;
3217                 rq->curr = next;
3218                 ++*switch_count;
3219 
3220                 trace_sched_switch(preempt, prev, next);
3221                 rq = context_switch(rq, prev, next); /* unlocks the rq */
3222         } else {
3223                 lockdep_unpin_lock(&rq->lock);
3224                 raw_spin_unlock_irq(&rq->lock);
3225         }
3226 
3227         balance_callback(rq);
3228 }
3229 STACK_FRAME_NON_STANDARD(__schedule); /* switch_to() */
3230 
3231 static inline void sched_submit_work(struct task_struct *tsk)
3232 {
3233         if (!tsk->state || tsk_is_pi_blocked(tsk))
3234                 return;
3235         /*
3236          * If we are going to sleep and we have plugged IO queued,
3237          * make sure to submit it to avoid deadlocks.
3238          */
3239         if (blk_needs_flush_plug(tsk))
3240                 blk_schedule_flush_plug(tsk);
3241 }
3242 
3243 asmlinkage __visible void __sched schedule(void)
3244 {
3245         struct task_struct *tsk = current;
3246 
3247         sched_submit_work(tsk);
3248         do {
3249                 preempt_disable();
3250                 __schedule(false);
3251                 sched_preempt_enable_no_resched();
3252         } while (need_resched());
3253 }
3254 EXPORT_SYMBOL(schedule);
3255 
3256 #ifdef CONFIG_CONTEXT_TRACKING
3257 asmlinkage __visible void __sched schedule_user(void)
3258 {
3259         /*
3260          * If we come here after a random call to set_need_resched(),
3261          * or we have been woken up remotely but the IPI has not yet arrived,
3262          * we haven't yet exited the RCU idle mode. Do it here manually until
3263          * we find a better solution.
3264          *
3265          * NB: There are buggy callers of this function.  Ideally we
3266          * should warn if prev_state != CONTEXT_USER, but that will trigger
3267          * too frequently to make sense yet.
3268          */
3269         enum ctx_state prev_state = exception_enter();
3270         schedule();
3271         exception_exit(prev_state);
3272 }
3273 #endif
3274 
3275 /**
3276  * schedule_preempt_disabled - called with preemption disabled
3277  *
3278  * Returns with preemption disabled. Note: preempt_count must be 1
3279  */
3280 void __sched schedule_preempt_disabled(void)
3281 {
3282         sched_preempt_enable_no_resched();
3283         schedule();
3284         preempt_disable();
3285 }
3286 
3287 static void __sched notrace preempt_schedule_common(void)
3288 {
3289         do {
3290                 preempt_disable_notrace();
3291                 __schedule(true);
3292                 preempt_enable_no_resched_notrace();
3293 
3294                 /*
3295                  * Check again in case we missed a preemption opportunity
3296                  * between schedule and now.
3297                  */
3298         } while (need_resched());
3299 }
3300 
3301 #ifdef CONFIG_PREEMPT
3302 /*
3303  * this is the entry point to schedule() from in-kernel preemption
3304  * off of preempt_enable. Kernel preemptions off return from interrupt
3305  * occur there and call schedule directly.
3306  */
3307 asmlinkage __visible void __sched notrace preempt_schedule(void)
3308 {
3309         /*
3310          * If there is a non-zero preempt_count or interrupts are disabled,
3311          * we do not want to preempt the current task. Just return..
3312          */
3313         if (likely(!preemptible()))
3314                 return;
3315 
3316         preempt_schedule_common();
3317 }
3318 NOKPROBE_SYMBOL(preempt_schedule);
3319 EXPORT_SYMBOL(preempt_schedule);
3320 
3321 /**
3322  * preempt_schedule_notrace - preempt_schedule called by tracing
3323  *
3324  * The tracing infrastructure uses preempt_enable_notrace to prevent
3325  * recursion and tracing preempt enabling caused by the tracing
3326  * infrastructure itself. But as tracing can happen in areas coming
3327  * from userspace or just about to enter userspace, a preempt enable
3328  * can occur before user_exit() is called. This will cause the scheduler
3329  * to be called when the system is still in usermode.
3330  *
3331  * To prevent this, the preempt_enable_notrace will use this function
3332  * instead of preempt_schedule() to exit user context if needed before
3333  * calling the scheduler.
3334  */
3335 asmlinkage __visible void __sched notrace preempt_schedule_notrace(void)
3336 {
3337         enum ctx_state prev_ctx;
3338 
3339         if (likely(!preemptible()))
3340                 return;
3341 
3342         do {
3343                 preempt_disable_notrace();
3344                 /*
3345                  * Needs preempt disabled in case user_exit() is traced
3346                  * and the tracer calls preempt_enable_notrace() causing
3347                  * an infinite recursion.
3348                  */
3349                 prev_ctx = exception_enter();
3350                 __schedule(true);
3351                 exception_exit(prev_ctx);
3352 
3353                 preempt_enable_no_resched_notrace();
3354         } while (need_resched());
3355 }
3356 EXPORT_SYMBOL_GPL(preempt_schedule_notrace);
3357 
3358 #endif /* CONFIG_PREEMPT */
3359 
3360 /*
3361  * this is the entry point to schedule() from kernel preemption
3362  * off of irq context.
3363  * Note, that this is called and return with irqs disabled. This will
3364  * protect us against recursive calling from irq.
3365  */
3366 asmlinkage __visible void __sched preempt_schedule_irq(void)
3367 {
3368         enum ctx_state prev_state;
3369 
3370         /* Catch callers which need to be fixed */
3371         BUG_ON(preempt_count() || !irqs_disabled());
3372 
3373         prev_state = exception_enter();
3374 
3375         do {
3376                 preempt_disable();
3377                 local_irq_enable();
3378                 __schedule(true);
3379                 local_irq_disable();
3380                 sched_preempt_enable_no_resched();
3381         } while (need_resched());
3382 
3383         exception_exit(prev_state);
3384 }
3385 
3386 int default_wake_function(wait_queue_t *curr, unsigned mode, int wake_flags,
3387                           void *key)
3388 {
3389         return try_to_wake_up(curr->private, mode, wake_flags);
3390 }
3391 EXPORT_SYMBOL(default_wake_function);
3392 
3393 #ifdef CONFIG_RT_MUTEXES
3394 
3395 /*
3396  * rt_mutex_setprio - set the current priority of a task
3397  * @p: task
3398  * @prio: prio value (kernel-internal form)
3399  *
3400  * This function changes the 'effective' priority of a task. It does
3401  * not touch ->normal_prio like __setscheduler().
3402  *
3403  * Used by the rt_mutex code to implement priority inheritance
3404  * logic. Call site only calls if the priority of the task changed.
3405  */
3406 void rt_mutex_setprio(struct task_struct *p, int prio)
3407 {
3408         int oldprio, queued, running, queue_flag = DEQUEUE_SAVE | DEQUEUE_MOVE;
3409         struct rq *rq;
3410         const struct sched_class *prev_class;
3411 
3412         BUG_ON(prio > MAX_PRIO);
3413 
3414         rq = __task_rq_lock(p);
3415 
3416         /*
3417          * Idle task boosting is a nono in general. There is one
3418          * exception, when PREEMPT_RT and NOHZ is active:
3419          *
3420          * The idle task calls get_next_timer_interrupt() and holds
3421          * the timer wheel base->lock on the CPU and another CPU wants
3422          * to access the timer (probably to cancel it). We can safely
3423          * ignore the boosting request, as the idle CPU runs this code
3424          * with interrupts disabled and will complete the lock
3425          * protected section without being interrupted. So there is no
3426          * real need to boost.
3427          */
3428         if (unlikely(p == rq->idle)) {
3429                 WARN_ON(p != rq->curr);
3430                 WARN_ON(p->pi_blocked_on);
3431                 goto out_unlock;
3432         }
3433 
3434         trace_sched_pi_setprio(p, prio);
3435         oldprio = p->prio;
3436 
3437         if (oldprio == prio)
3438                 queue_flag &= ~DEQUEUE_MOVE;
3439 
3440         prev_class = p->sched_class;
3441         queued = task_on_rq_queued(p);
3442         running = task_current(rq, p);
3443         if (queued)
3444                 dequeue_task(rq, p, queue_flag);
3445         if (running)
3446                 put_prev_task(rq, p);
3447 
3448         /*
3449          * Boosting condition are:
3450          * 1. -rt task is running and holds mutex A
3451          *      --> -dl task blocks on mutex A
3452          *
3453          * 2. -dl task is running and holds mutex A
3454          *      --> -dl task blocks on mutex A and could preempt the
3455          *          running task
3456          */
3457         if (dl_prio(prio)) {
3458                 struct task_struct *pi_task = rt_mutex_get_top_task(p);
3459                 if (!dl_prio(p->normal_prio) ||
3460                     (pi_task && dl_entity_preempt(&pi_task->dl, &p->dl))) {
3461                         p->dl.dl_boosted = 1;
3462                         queue_flag |= ENQUEUE_REPLENISH;
3463                 } else
3464                         p->dl.dl_boosted = 0;
3465                 p->sched_class = &dl_sched_class;
3466         } else if (rt_prio(prio)) {
3467                 if (dl_prio(oldprio))
3468                         p->dl.dl_boosted = 0;
3469                 if (oldprio < prio)
3470                         queue_flag |= ENQUEUE_HEAD;
3471                 p->sched_class = &rt_sched_class;
3472         } else {
3473                 if (dl_prio(oldprio))
3474                         p->dl.dl_boosted = 0;
3475                 if (rt_prio(oldprio))
3476                         p->rt.timeout = 0;
3477                 p->sched_class = &fair_sched_class;
3478         }
3479 
3480         p->prio = prio;
3481 
3482         if (running)
3483                 p->sched_class->set_curr_task(rq);
3484         if (queued)
3485                 enqueue_task(rq, p, queue_flag);
3486 
3487         check_class_changed(rq, p, prev_class, oldprio);
3488 out_unlock:
3489         preempt_disable(); /* avoid rq from going away on us */
3490         __task_rq_unlock(rq);
3491 
3492         balance_callback(rq);
3493         preempt_enable();
3494 }
3495 #endif
3496 
3497 void set_user_nice(struct task_struct *p, long nice)
3498 {
3499         int old_prio, delta, queued;
3500         unsigned long flags;
3501         struct rq *rq;
3502 
3503         if (task_nice(p) == nice || nice < MIN_NICE || nice > MAX_NICE)
3504                 return;
3505         /*
3506          * We have to be careful, if called from sys_setpriority(),
3507          * the task might be in the middle of scheduling on another CPU.
3508          */
3509         rq = task_rq_lock(p, &flags);
3510         /*
3511          * The RT priorities are set via sched_setscheduler(), but we still
3512          * allow the 'normal' nice value to be set - but as expected
3513          * it wont have any effect on scheduling until the task is
3514          * SCHED_DEADLINE, SCHED_FIFO or SCHED_RR:
3515          */
3516         if (task_has_dl_policy(p) || task_has_rt_policy(p)) {
3517                 p->static_prio = NICE_TO_PRIO(nice);
3518                 goto out_unlock;
3519         }
3520         queued = task_on_rq_queued(p);
3521         if (queued)
3522                 dequeue_task(rq, p, DEQUEUE_SAVE);
3523 
3524         p->static_prio = NICE_TO_PRIO(nice);
3525         set_load_weight(p);
3526         old_prio = p->prio;
3527         p->prio = effective_prio(p);
3528         delta = p->prio - old_prio;
3529 
3530         if (queued) {
3531                 enqueue_task(rq, p, ENQUEUE_RESTORE);
3532                 /*
3533                  * If the task increased its priority or is running and
3534                  * lowered its priority, then reschedule its CPU:
3535                  */
3536                 if (delta < 0 || (delta > 0 && task_running(rq, p)))
3537                         resched_curr(rq);
3538         }
3539 out_unlock:
3540         task_rq_unlock(rq, p, &flags);
3541 }
3542 EXPORT_SYMBOL(set_user_nice);
3543 
3544 /*
3545  * can_nice - check if a task can reduce its nice value
3546  * @p: task
3547  * @nice: nice value
3548  */
3549 int can_nice(const struct task_struct *p, const int nice)
3550 {
3551         /* convert nice value [19,-20] to rlimit style value [1,40] */
3552         int nice_rlim = nice_to_rlimit(nice);
3553 
3554         return (nice_rlim <= task_rlimit(p, RLIMIT_NICE) ||
3555                 capable(CAP_SYS_NICE));
3556 }
3557 
3558 #ifdef __ARCH_WANT_SYS_NICE
3559 
3560 /*
3561  * sys_nice - change the priority of the current process.
3562  * @increment: priority increment
3563  *
3564  * sys_setpriority is a more generic, but much slower function that
3565  * does similar things.
3566  */
3567 SYSCALL_DEFINE1(nice, int, increment)
3568 {
3569         long nice, retval;
3570 
3571         /*
3572          * Setpriority might change our priority at the same moment.
3573          * We don't have to worry. Conceptually one call occurs first
3574          * and we have a single winner.
3575          */
3576         increment = clamp(increment, -NICE_WIDTH, NICE_WIDTH);
3577         nice = task_nice(current) + increment;
3578 
3579         nice = clamp_val(nice, MIN_NICE, MAX_NICE);
3580         if (increment < 0 && !can_nice(current, nice))
3581                 return -EPERM;
3582 
3583         retval = security_task_setnice(current, nice);
3584         if (retval)
3585                 return retval;
3586 
3587         set_user_nice(current, nice);
3588         return 0;
3589 }
3590 
3591 #endif
3592 
3593 /**
3594  * task_prio - return the priority value of a given task.
3595  * @p: the task in question.
3596  *
3597  * Return: The priority value as seen by users in /proc.
3598  * RT tasks are offset by -200. Normal tasks are centered
3599  * around 0, value goes from -16 to +15.
3600  */
3601 int task_prio(const struct task_struct *p)
3602 {
3603         return p->prio - MAX_RT_PRIO;
3604 }
3605 
3606 /**
3607  * idle_cpu - is a given cpu idle currently?
3608  * @cpu: the processor in question.
3609  *
3610  * Return: 1 if the CPU is currently idle. 0 otherwise.
3611  */
3612 int idle_cpu(int cpu)
3613 {
3614         struct rq *rq = cpu_rq(cpu);
3615 
3616         if (rq->curr != rq->idle)
3617                 return 0;
3618 
3619         if (rq->nr_running)
3620                 return 0;
3621 
3622 #ifdef CONFIG_SMP
3623         if (!llist_empty(&rq->wake_list))
3624                 return 0;
3625 #endif
3626 
3627         return 1;
3628 }
3629 
3630 /**
3631  * idle_task - return the idle task for a given cpu.
3632  * @cpu: the processor in question.
3633  *
3634  * Return: The idle task for the cpu @cpu.
3635  */
3636 struct task_struct *idle_task(int cpu)
3637 {
3638         return cpu_rq(cpu)->idle;
3639 }
3640 
3641 /**
3642  * find_process_by_pid - find a process with a matching PID value.
3643  * @pid: the pid in question.
3644  *
3645  * The task of @pid, if found. %NULL otherwise.
3646  */
3647 static struct task_struct *find_process_by_pid(pid_t pid)
3648 {
3649         return pid ? find_task_by_vpid(pid) : current;
3650 }
3651 
3652 /*
3653  * This function initializes the sched_dl_entity of a newly becoming
3654  * SCHED_DEADLINE task.
3655  *
3656  * Only the static values are considered here, the actual runtime and the
3657  * absolute deadline will be properly calculated when the task is enqueued
3658  * for the first time with its new policy.
3659  */
3660 static void
3661 __setparam_dl(struct task_struct *p, const struct sched_attr *attr)
3662 {
3663         struct sched_dl_entity *dl_se = &p->dl;
3664 
3665         dl_se->dl_runtime = attr->sched_runtime;
3666         dl_se->dl_deadline = attr->sched_deadline;
3667         dl_se->dl_period = attr->sched_period ?: dl_se->dl_deadline;
3668         dl_se->flags = attr->sched_flags;
3669         dl_se->dl_bw = to_ratio(dl_se->dl_period, dl_se->dl_runtime);
3670 
3671         /*
3672          * Changing the parameters of a task is 'tricky' and we're not doing
3673          * the correct thing -- also see task_dead_dl() and switched_from_dl().
3674          *
3675          * What we SHOULD do is delay the bandwidth release until the 0-lag
3676          * point. This would include retaining the task_struct until that time
3677          * and change dl_overflow() to not immediately decrement the current
3678          * amount.
3679          *
3680          * Instead we retain the current runtime/deadline and let the new
3681          * parameters take effect after the current reservation period lapses.
3682          * This is safe (albeit pessimistic) because the 0-lag point is always
3683          * before the current scheduling deadline.
3684          *
3685          * We can still have temporary overloads because we do not delay the
3686          * change in bandwidth until that time; so admission control is
3687          * not on the safe side. It does however guarantee tasks will never
3688          * consume more than promised.
3689          */
3690 }
3691 
3692 /*
3693  * sched_setparam() passes in -1 for its policy, to let the functions
3694  * it calls know not to change it.
3695  */
3696 #define SETPARAM_POLICY -1
3697 
3698 static void __setscheduler_params(struct task_struct *p,
3699                 const struct sched_attr *attr)
3700 {
3701         int policy = attr->sched_policy;
3702 
3703         if (policy == SETPARAM_POLICY)
3704                 policy = p->policy;
3705 
3706         p->policy = policy;
3707 
3708         if (dl_policy(policy))
3709                 __setparam_dl(p, attr);
3710         else if (fair_policy(policy))
3711                 p->static_prio = NICE_TO_PRIO(attr->sched_nice);
3712 
3713         /*
3714          * __sched_setscheduler() ensures attr->sched_priority == 0 when
3715          * !rt_policy. Always setting this ensures that things like
3716          * getparam()/getattr() don't report silly values for !rt tasks.
3717          */
3718         p->rt_priority = attr->sched_priority;
3719         p->normal_prio = normal_prio(p);
3720         set_load_weight(p);
3721 }
3722 
3723 /* Actually do priority change: must hold pi & rq lock. */
3724 static void __setscheduler(struct rq *rq, struct task_struct *p,
3725                            const struct sched_attr *attr, bool keep_boost)
3726 {
3727         __setscheduler_params(p, attr);
3728 
3729         /*
3730          * Keep a potential priority boosting if called from
3731          * sched_setscheduler().
3732          */
3733         if (keep_boost)
3734                 p->prio = rt_mutex_get_effective_prio(p, normal_prio(p));
3735         else
3736                 p->prio = normal_prio(p);
3737 
3738         if (dl_prio(p->prio))
3739                 p->sched_class = &dl_sched_class;
3740         else if (rt_prio(p->prio))
3741                 p->sched_class = &rt_sched_class;
3742         else
3743                 p->sched_class = &fair_sched_class;
3744 }
3745 
3746 static void
3747 __getparam_dl(struct task_struct *p, struct sched_attr *attr)
3748 {
3749         struct sched_dl_entity *dl_se = &p->dl;
3750 
3751         attr->sched_priority = p->rt_priority;
3752         attr->sched_runtime = dl_se->dl_runtime;
3753         attr->sched_deadline = dl_se->dl_deadline;
3754         attr->sched_period = dl_se->dl_period;
3755         attr->sched_flags = dl_se->flags;
3756 }
3757 
3758 /*
3759  * This function validates the new parameters of a -deadline task.
3760  * We ask for the deadline not being zero, and greater or equal
3761  * than the runtime, as well as the period of being zero or
3762  * greater than deadline. Furthermore, we have to be sure that
3763  * user parameters are above the internal resolution of 1us (we
3764  * check sched_runtime only since it is always the smaller one) and
3765  * below 2^63 ns (we have to check both sched_deadline and
3766  * sched_period, as the latter can be zero).
3767  */
3768 static bool
3769 __checkparam_dl(const struct sched_attr *attr)
3770 {
3771         /* deadline != 0 */
3772         if (attr->sched_deadline == 0)
3773                 return false;
3774 
3775         /*
3776          * Since we truncate DL_SCALE bits, make sure we're at least
3777          * that big.
3778          */
3779         if (attr->sched_runtime < (1ULL << DL_SCALE))
3780                 return false;
3781 
3782         /*
3783          * Since we use the MSB for wrap-around and sign issues, make
3784          * sure it's not set (mind that period can be equal to zero).
3785          */
3786         if (attr->sched_deadline & (1ULL << 63) ||
3787             attr->sched_period & (1ULL << 63))
3788                 return false;
3789 
3790         /* runtime <= deadline <= period (if period != 0) */
3791         if ((attr->sched_period != 0 &&
3792              attr->sched_period < attr->sched_deadline) ||
3793             attr->sched_deadline < attr->sched_runtime)
3794                 return false;
3795 
3796         return true;
3797 }
3798 
3799 /*
3800  * check the target process has a UID that matches the current process's
3801  */
3802 static bool check_same_owner(struct task_struct *p)
3803 {
3804         const struct cred *cred = current_cred(), *pcred;
3805         bool match;
3806 
3807         rcu_read_lock();
3808         pcred = __task_cred(p);
3809         match = (uid_eq(cred->euid, pcred->euid) ||
3810                  uid_eq(cred->euid, pcred->uid));
3811         rcu_read_unlock();
3812         return match;
3813 }
3814 
3815 static bool dl_param_changed(struct task_struct *p,
3816                 const struct sched_attr *attr)
3817 {
3818         struct sched_dl_entity *dl_se = &p->dl;
3819 
3820         if (dl_se->dl_runtime != attr->sched_runtime ||
3821                 dl_se->dl_deadline != attr->sched_deadline ||
3822                 dl_se->dl_period != attr->sched_period ||
3823                 dl_se->flags != attr->sched_flags)
3824                 return true;
3825 
3826         return false;
3827 }
3828 
3829 static int __sched_setscheduler(struct task_struct *p,
3830                                 const struct sched_attr *attr,
3831                                 bool user, bool pi)
3832 {
3833         int newprio = dl_policy(attr->sched_policy) ? MAX_DL_PRIO - 1 :
3834                       MAX_RT_PRIO - 1 - attr->sched_priority;
3835         int retval, oldprio, oldpolicy = -1, queued, running;
3836         int new_effective_prio, policy = attr->sched_policy;
3837         unsigned long flags;
3838         const struct sched_class *prev_class;
3839         struct rq *rq;
3840         int reset_on_fork;
3841         int queue_flags = DEQUEUE_SAVE | DEQUEUE_MOVE;
3842 
3843         /* may grab non-irq protected spin_locks */
3844         BUG_ON(in_interrupt());
3845 recheck:
3846         /* double check policy once rq lock held */
3847         if (policy < 0) {
3848                 reset_on_fork = p->sched_reset_on_fork;
3849                 policy = oldpolicy = p->policy;
3850         } else {
3851                 reset_on_fork = !!(attr->sched_flags & SCHED_FLAG_RESET_ON_FORK);
3852 
3853                 if (!valid_policy(policy))
3854                         return -EINVAL;
3855         }
3856 
3857         if (attr->sched_flags & ~(SCHED_FLAG_RESET_ON_FORK))
3858                 return -EINVAL;
3859 
3860         /*
3861          * Valid priorities for SCHED_FIFO and SCHED_RR are
3862          * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL,
3863          * SCHED_BATCH and SCHED_IDLE is 0.
3864          */
3865         if ((p->mm && attr->sched_priority > MAX_USER_RT_PRIO-1) ||
3866             (!p->mm && attr->sched_priority > MAX_RT_PRIO-1))
3867                 return -EINVAL;
3868         if ((dl_policy(policy) && !__checkparam_dl(attr)) ||
3869             (rt_policy(policy) != (attr->sched_priority != 0)))
3870                 return -EINVAL;
3871 
3872         /*
3873          * Allow unprivileged RT tasks to decrease priority:
3874          */
3875         if (user && !capable(CAP_SYS_NICE)) {
3876                 if (fair_policy(policy)) {
3877                         if (attr->sched_nice < task_nice(p) &&
3878                             !can_nice(p, attr->sched_nice))
3879                                 return -EPERM;
3880                 }
3881 
3882                 if (rt_policy(policy)) {
3883                         unsigned long rlim_rtprio =
3884                                         task_rlimit(p, RLIMIT_RTPRIO);
3885 
3886                         /* can't set/change the rt policy */
3887                         if (policy != p->policy && !rlim_rtprio)
3888                                 return -EPERM;
3889 
3890                         /* can't increase priority */
3891                         if (attr->sched_priority > p->rt_priority &&
3892                             attr->sched_priority > rlim_rtprio)
3893                                 return -EPERM;
3894                 }
3895 
3896                  /*
3897                   * Can't set/change SCHED_DEADLINE policy at all for now
3898                   * (safest behavior); in the future we would like to allow
3899                   * unprivileged DL tasks to increase their relative deadline
3900                   * or reduce their runtime (both ways reducing utilization)
3901                   */
3902                 if (dl_policy(policy))
3903                         return -EPERM;
3904 
3905                 /*
3906                  * Treat SCHED_IDLE as nice 20. Only allow a switch to
3907                  * SCHED_NORMAL if the RLIMIT_NICE would normally permit it.
3908                  */
3909                 if (idle_policy(p->policy) && !idle_policy(policy)) {
3910                         if (!can_nice(p, task_nice(p)))
3911                                 return -EPERM;
3912                 }
3913 
3914                 /* can't change other user's priorities */
3915                 if (!check_same_owner(p))
3916                         return -EPERM;
3917 
3918                 /* Normal users shall not reset the sched_reset_on_fork flag */
3919                 if (p->sched_reset_on_fork && !reset_on_fork)
3920                         return -EPERM;
3921         }
3922 
3923         if (user) {
3924                 retval = security_task_setscheduler(p);
3925                 if (retval)
3926                         return retval;
3927         }
3928 
3929         /*
3930          * make sure no PI-waiters arrive (or leave) while we are
3931          * changing the priority of the task:
3932          *
3933          * To be able to change p->policy safely, the appropriate
3934          * runqueue lock must be held.
3935          */
3936         rq = task_rq_lock(p, &flags);
3937 
3938         /*
3939          * Changing the policy of the stop threads its a very bad idea
3940          */
3941         if (p == rq->stop) {
3942                 task_rq_unlock(rq, p, &flags);
3943                 return -EINVAL;
3944         }
3945 
3946         /*
3947          * If not changing anything there's no need to proceed further,
3948          * but store a possible modification of reset_on_fork.
3949          */
3950         if (unlikely(policy == p->policy)) {
3951                 if (fair_policy(policy) && attr->sched_nice != task_nice(p))
3952                         goto change;
3953                 if (rt_policy(policy) && attr->sched_priority != p->rt_priority)
3954                         goto change;
3955                 if (dl_policy(policy) && dl_param_changed(p, attr))
3956                         goto change;
3957 
3958                 p->sched_reset_on_fork = reset_on_fork;
3959                 task_rq_unlock(rq, p, &flags);
3960                 return 0;
3961         }
3962 change:
3963 
3964         if (user) {
3965 #ifdef CONFIG_RT_GROUP_SCHED
3966                 /*
3967                  * Do not allow realtime tasks into groups that have no runtime
3968                  * assigned.
3969                  */
3970                 if (rt_bandwidth_enabled() && rt_policy(policy) &&
3971                                 task_group(p)->rt_bandwidth.rt_runtime == 0 &&
3972                                 !task_group_is_autogroup(task_group(p))) {
3973                         task_rq_unlock(rq, p, &flags);
3974                         return -EPERM;
3975                 }
3976 #endif
3977 #ifdef CONFIG_SMP
3978                 if (dl_bandwidth_enabled() && dl_policy(policy)) {
3979                         cpumask_t *span = rq->rd->span;
3980 
3981                         /*
3982                          * Don't allow tasks with an affinity mask smaller than
3983                          * the entire root_domain to become SCHED_DEADLINE. We
3984                          * will also fail if there's no bandwidth available.
3985                          */
3986                         if (!cpumask_subset(span, &p->cpus_allowed) ||
3987                             rq->rd->dl_bw.bw == 0) {
3988                                 task_rq_unlock(rq, p, &flags);
3989                                 return -EPERM;
3990                         }
3991                 }
3992 #endif
3993         }
3994 
3995         /* recheck policy now with rq lock held */
3996         if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) {
3997                 policy = oldpolicy = -1;
3998                 task_rq_unlock(rq, p, &flags);
3999                 goto recheck;
4000         }
4001 
4002         /*
4003          * If setscheduling to SCHED_DEADLINE (or changing the parameters
4004          * of a SCHED_DEADLINE task) we need to check if enough bandwidth
4005          * is available.
4006          */
4007         if ((dl_policy(policy) || dl_task(p)) && dl_overflow(p, policy, attr)) {
4008                 task_rq_unlock(rq, p, &flags);
4009                 return -EBUSY;
4010         }
4011 
4012         p->sched_reset_on_fork = reset_on_fork;
4013         oldprio = p->prio;
4014 
4015         if (pi) {
4016                 /*
4017                  * Take priority boosted tasks into account. If the new
4018                  * effective priority is unchanged, we just store the new
4019                  * normal parameters and do not touch the scheduler class and
4020                  * the runqueue. This will be done when the task deboost
4021                  * itself.
4022                  */
4023                 new_effective_prio = rt_mutex_get_effective_prio(p, newprio);
4024                 if (new_effective_prio == oldprio)
4025                         queue_flags &= ~DEQUEUE_MOVE;
4026         }
4027 
4028         queued = task_on_rq_queued(p);
4029         running = task_current(rq, p);
4030         if (queued)
4031                 dequeue_task(rq, p, queue_flags);
4032         if (running)
4033                 put_prev_task(rq, p);
4034 
4035         prev_class = p->sched_class;
4036         __setscheduler(rq, p, attr, pi);
4037 
4038         if (running)
4039                 p->sched_class->set_curr_task(rq);
4040         if (queued) {
4041                 /*
4042                  * We enqueue to tail when the priority of a task is
4043                  * increased (user space view).
4044                  */
4045                 if (oldprio < p->prio)
4046                         queue_flags |= ENQUEUE_HEAD;
4047 
4048                 enqueue_task(rq, p, queue_flags);
4049         }
4050 
4051         check_class_changed(rq, p, prev_class, oldprio);
4052         preempt_disable(); /* avoid rq from going away on us */
4053         task_rq_unlock(rq, p, &flags);
4054 
4055         if (pi)
4056                 rt_mutex_adjust_pi(p);
4057 
4058         /*
4059          * Run balance callbacks after we've adjusted the PI chain.
4060          */
4061         balance_callback(rq);
4062         preempt_enable();
4063 
4064         return 0;
4065 }
4066 
4067 static int _sched_setscheduler(struct task_struct *p, int policy,
4068                                const struct sched_param *param, bool check)
4069 {
4070         struct sched_attr attr = {
4071                 .sched_policy   = policy,
4072                 .sched_priority = param->sched_priority,
4073                 .sched_nice     = PRIO_TO_NICE(p->static_prio),
4074         };
4075 
4076         /* Fixup the legacy SCHED_RESET_ON_FORK hack. */
4077         if ((policy != SETPARAM_POLICY) && (policy & SCHED_RESET_ON_FORK)) {
4078                 attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK;
4079                 policy &= ~SCHED_RESET_ON_FORK;
4080                 attr.sched_policy = policy;
4081         }
4082 
4083         return __sched_setscheduler(p, &attr, check, true);
4084 }
4085 /**
4086  * sched_setscheduler - change the scheduling policy and/or RT priority of a thread.
4087  * @p: the task in question.
4088  * @policy: new policy.
4089  * @param: structure containing the new RT priority.
4090  *
4091  * Return: 0 on success. An error code otherwise.
4092  *
4093  * NOTE that the task may be already dead.
4094  */
4095 int sched_setscheduler(struct task_struct *p, int policy,
4096                        const struct sched_param *param)
4097 {
4098         return _sched_setscheduler(p, policy, param, true);
4099 }
4100 EXPORT_SYMBOL_GPL(sched_setscheduler);
4101 
4102 int sched_setattr(struct task_struct *p, const struct sched_attr *attr)
4103 {
4104         return __sched_setscheduler(p, attr, true, true);
4105 }
4106 EXPORT_SYMBOL_GPL(sched_setattr);
4107 
4108 /**
4109  * sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace.
4110  * @p: the task in question.
4111  * @policy: new policy.
4112  * @param: structure containing the new RT priority.
4113  *
4114  * Just like sched_setscheduler, only don't bother checking if the
4115  * current context has permission.  For example, this is needed in
4116  * stop_machine(): we create temporary high priority worker threads,
4117  * but our caller might not have that capability.
4118  *
4119  * Return: 0 on success. An error code otherwise.
4120  */
4121 int sched_setscheduler_nocheck(struct task_struct *p, int policy,
4122                                const struct sched_param *param)
4123 {
4124         return _sched_setscheduler(p, policy, param, false);
4125 }
4126 EXPORT_SYMBOL_GPL(sched_setscheduler_nocheck);
4127 
4128 static int
4129 do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param)
4130 {
4131         struct sched_param lparam;
4132         struct task_struct *p;
4133         int retval;
4134 
4135         if (!param || pid < 0)
4136                 return -EINVAL;
4137         if (copy_from_user(&lparam, param, sizeof(struct sched_param)))
4138                 return -EFAULT;
4139 
4140         rcu_read_lock();
4141         retval = -ESRCH;
4142         p = find_process_by_pid(pid);
4143         if (p != NULL)
4144                 retval = sched_setscheduler(p, policy, &lparam);
4145         rcu_read_unlock();
4146 
4147         return retval;
4148 }
4149 
4150 /*
4151  * Mimics kernel/events/core.c perf_copy_attr().
4152  */
4153 static int sched_copy_attr(struct sched_attr __user *uattr,
4154                            struct sched_attr *attr)
4155 {
4156         u32 size;
4157         int ret;
4158 
4159         if (!access_ok(VERIFY_WRITE, uattr, SCHED_ATTR_SIZE_VER0))
4160                 return -EFAULT;
4161 
4162         /*
4163          * zero the full structure, so that a short copy will be nice.
4164          */
4165         memset(attr, 0, sizeof(*attr));
4166 
4167         ret = get_user(size, &uattr->size);
4168         if (ret)
4169                 return ret;
4170 
4171         if (size > PAGE_SIZE)   /* silly large */
4172                 goto err_size;
4173 
4174         if (!size)              /* abi compat */
4175                 size = SCHED_ATTR_SIZE_VER0;
4176 
4177         if (size < SCHED_ATTR_SIZE_VER0)
4178                 goto err_size;
4179 
4180         /*
4181          * If we're handed a bigger struct than we know of,
4182          * ensure all the unknown bits are 0 - i.e. new
4183          * user-space does not rely on any kernel feature
4184          * extensions we dont know about yet.
4185          */
4186         if (size > sizeof(*attr)) {
4187                 unsigned char __user *addr;
4188                 unsigned char __user *end;
4189                 unsigned char val;
4190 
4191                 addr = (void __user *)uattr + sizeof(*attr);
4192                 end  = (void __user *)uattr + size;
4193 
4194                 for (; addr < end; addr++) {
4195                         ret = get_user(val, addr);
4196                         if (ret)
4197                                 return ret;
4198                         if (val)
4199                                 goto err_size;
4200                 }
4201                 size = sizeof(*attr);
4202         }
4203 
4204         ret = copy_from_user(attr, uattr, size);
4205         if (ret)
4206                 return -EFAULT;
4207 
4208         /*
4209          * XXX: do we want to be lenient like existing syscalls; or do we want
4210          * to be strict and return an error on out-of-bounds values?
4211          */
4212         attr->sched_nice = clamp(attr->sched_nice, MIN_NICE, MAX_NICE);
4213 
4214         return 0;
4215 
4216 err_size:
4217         put_user(sizeof(*attr), &uattr->size);
4218         return -E2BIG;
4219 }
4220 
4221 /**
4222  * sys_sched_setscheduler - set/change the scheduler policy and RT priority
4223  * @pid: the pid in question.
4224  * @policy: new policy.
4225  * @param: structure containing the new RT priority.
4226  *
4227  * Return: 0 on success. An error code otherwise.
4228  */
4229 SYSCALL_DEFINE3(sched_setscheduler, pid_t, pid, int, policy,
4230                 struct sched_param __user *, param)
4231 {
4232         /* negative values for policy are not valid */
4233         if (policy < 0)
4234                 return -EINVAL;
4235 
4236         return do_sched_setscheduler(pid, policy, param);
4237 }
4238 
4239 /**
4240  * sys_sched_setparam - set/change the RT priority of a thread
4241  * @pid: the pid in question.
4242  * @param: structure containing the new RT priority.
4243  *
4244  * Return: 0 on success. An error code otherwise.
4245  */
4246 SYSCALL_DEFINE2(sched_setparam, pid_t, pid, struct sched_param __user *, param)
4247 {
4248         return do_sched_setscheduler(pid, SETPARAM_POLICY, param);
4249 }
4250 
4251 /**
4252  * sys_sched_setattr - same as above, but with extended sched_attr
4253  * @pid: the pid in question.
4254  * @uattr: structure containing the extended parameters.
4255  * @flags: for future extension.
4256  */
4257 SYSCALL_DEFINE3(sched_setattr, pid_t, pid, struct sched_attr __user *, uattr,
4258                                unsigned int, flags)
4259 {
4260         struct sched_attr attr;
4261         struct task_struct *p;
4262         int retval;
4263 
4264         if (!uattr || pid < 0 || flags)
4265                 return -EINVAL;
4266 
4267         retval = sched_copy_attr(uattr, &attr);
4268         if (retval)
4269                 return retval;
4270 
4271         if ((int)attr.sched_policy < 0)
4272                 return -EINVAL;
4273 
4274         rcu_read_lock();
4275         retval = -ESRCH;
4276         p = find_process_by_pid(pid);
4277         if (p != NULL)
4278                 retval = sched_setattr(p, &attr);
4279         rcu_read_unlock();
4280 
4281         return retval;
4282 }
4283 
4284 /**
4285  * sys_sched_getscheduler - get the policy (scheduling class) of a thread
4286  * @pid: the pid in question.
4287  *
4288  * Return: On success, the policy of the thread. Otherwise, a negative error
4289  * code.
4290  */
4291 SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid)
4292 {
4293         struct task_struct *p;
4294         int retval;
4295 
4296         if (pid < 0)
4297                 return -EINVAL;
4298 
4299         retval = -ESRCH;
4300         rcu_read_lock();
4301         p = find_process_by_pid(pid);
4302         if (p) {
4303                 retval = security_task_getscheduler(p);
4304                 if (!retval)
4305                         retval = p->policy
4306                                 | (p->sched_reset_on_fork ? SCHED_RESET_ON_FORK : 0);
4307         }
4308         rcu_read_unlock();
4309         return retval;
4310 }
4311 
4312 /**
4313  * sys_sched_getparam - get the RT priority of a thread
4314  * @pid: the pid in question.
4315  * @param: structure containing the RT priority.
4316  *
4317  * Return: On success, 0 and the RT priority is in @param. Otherwise, an error
4318  * code.
4319  */
4320 SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param)
4321 {
4322         struct sched_param lp = { .sched_priority = 0 };
4323         struct task_struct *p;
4324         int retval;
4325 
4326         if (!param || pid < 0)
4327                 return -EINVAL;
4328 
4329         rcu_read_lock();
4330         p = find_process_by_pid(pid);
4331         retval = -ESRCH;
4332         if (!p)
4333                 goto out_unlock;
4334 
4335         retval = security_task_getscheduler(p);
4336         if (retval)
4337                 goto out_unlock;
4338 
4339         if (task_has_rt_policy(p))
4340                 lp.sched_priority = p->rt_priority;
4341         rcu_read_unlock();
4342 
4343         /*
4344          * This one might sleep, we cannot do it with a spinlock held ...
4345          */
4346         retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0;
4347 
4348         return retval;
4349 
4350 out_unlock:
4351         rcu_read_unlock();
4352         return retval;
4353 }
4354 
4355 static int sched_read_attr(struct sched_attr __user *uattr,
4356                            struct sched_attr *attr,
4357                            unsigned int usize)
4358 {
4359         int ret;
4360 
4361         if (!access_ok(VERIFY_WRITE, uattr, usize))
4362                 return -EFAULT;
4363 
4364         /*
4365          * If we're handed a smaller struct than we know of,
4366          * ensure all the unknown bits are 0 - i.e. old
4367          * user-space does not get uncomplete information.
4368          */
4369         if (usize < sizeof(*attr)) {
4370                 unsigned char *addr;
4371                 unsigned char *end;
4372 
4373                 addr = (void *)attr + usize;
4374                 end  = (void *)attr + sizeof(*attr);
4375 
4376                 for (; addr < end; addr++) {
4377                         if (*addr)
4378                                 return -EFBIG;
4379                 }
4380 
4381                 attr->size = usize;
4382         }
4383 
4384         ret = copy_to_user(uattr, attr, attr->size);
4385         if (ret)
4386                 return -EFAULT;
4387 
4388         return 0;
4389 }
4390 
4391 /**
4392  * sys_sched_getattr - similar to sched_getparam, but with sched_attr
4393  * @pid: the pid in question.
4394  * @uattr: structure containing the extended parameters.
4395  * @size: sizeof(attr) for fwd/bwd comp.
4396  * @flags: for future extension.
4397  */
4398 SYSCALL_DEFINE4(sched_getattr, pid_t, pid, struct sched_attr __user *, uattr,
4399                 unsigned int, size, unsigned int, flags)
4400 {
4401         struct sched_attr attr = {
4402                 .size = sizeof(struct sched_attr),
4403         };
4404         struct task_struct *p;
4405         int retval;
4406 
4407         if (!uattr || pid < 0 || size > PAGE_SIZE ||
4408             size < SCHED_ATTR_SIZE_VER0 || flags)
4409                 return -EINVAL;
4410 
4411         rcu_read_lock();
4412         p = find_process_by_pid(pid);
4413         retval = -ESRCH;
4414         if (!p)
4415                 goto out_unlock;
4416 
4417         retval = security_task_getscheduler(p);
4418         if (retval)
4419                 goto out_unlock;
4420 
4421         attr.sched_policy = p->policy;
4422         if (p->sched_reset_on_fork)
4423                 attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK;
4424         if (task_has_dl_policy(p))
4425                 __getparam_dl(p, &attr);
4426         else if (task_has_rt_policy(p))
4427                 attr.sched_priority = p->rt_priority;
4428         else
4429                 attr.sched_nice = task_nice(p);
4430 
4431         rcu_read_unlock();
4432 
4433         retval = sched_read_attr(uattr, &attr, size);
4434         return retval;
4435 
4436 out_unlock:
4437         rcu_read_unlock();
4438         return retval;
4439 }
4440 
4441 long sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
4442 {
4443         cpumask_var_t cpus_allowed, new_mask;
4444         struct task_struct *p;
4445         int retval;
4446 
4447         rcu_read_lock();
4448 
4449         p = find_process_by_pid(pid);
4450         if (!p) {
4451                 rcu_read_unlock();
4452                 return -ESRCH;
4453         }
4454 
4455         /* Prevent p going away */
4456         get_task_struct(p);
4457         rcu_read_unlock();
4458 
4459         if (p->flags & PF_NO_SETAFFINITY) {
4460                 retval = -EINVAL;
4461                 goto out_put_task;
4462         }
4463         if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) {
4464                 retval = -ENOMEM;
4465                 goto out_put_task;
4466         }
4467         if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) {
4468                 retval = -ENOMEM;
4469                 goto out_free_cpus_allowed;
4470         }
4471         retval = -EPERM;
4472         if (!check_same_owner(p)) {
4473                 rcu_read_lock();
4474                 if (!ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE)) {
4475                         rcu_read_unlock();
4476                         goto out_free_new_mask;
4477                 }
4478                 rcu_read_unlock();
4479         }
4480 
4481         retval = security_task_setscheduler(p);
4482         if (retval)
4483                 goto out_free_new_mask;
4484 
4485 
4486         cpuset_cpus_allowed(p, cpus_allowed);
4487         cpumask_and(new_mask, in_mask, cpus_allowed);
4488 
4489         /*
4490          * Since bandwidth control happens on root_domain basis,
4491          * if admission test is enabled, we only admit -deadline
4492          * tasks allowed to run on all the CPUs in the task's
4493          * root_domain.
4494          */
4495 #ifdef CONFIG_SMP
4496         if (task_has_dl_policy(p) && dl_bandwidth_enabled()) {
4497                 rcu_read_lock();
4498                 if (!cpumask_subset(task_rq(p)->rd->span, new_mask)) {
4499                         retval = -EBUSY;
4500                         rcu_read_unlock();
4501                         goto out_free_new_mask;
4502                 }
4503                 rcu_read_unlock();
4504         }
4505 #endif
4506 again:
4507         retval = __set_cpus_allowed_ptr(p, new_mask, true);
4508 
4509         if (!retval) {
4510                 cpuset_cpus_allowed(p, cpus_allowed);
4511                 if (!cpumask_subset(new_mask, cpus_allowed)) {
4512                         /*
4513                          * We must have raced with a concurrent cpuset
4514                          * update. Just reset the cpus_allowed to the
4515                          * cpuset's cpus_allowed
4516                          */
4517                         cpumask_copy(new_mask, cpus_allowed);
4518                         goto again;
4519                 }
4520         }
4521 out_free_new_mask:
4522         free_cpumask_var(new_mask);
4523 out_free_cpus_allowed:
4524         free_cpumask_var(cpus_allowed);
4525 out_put_task:
4526         put_task_struct(p);
4527         return retval;
4528 }
4529 
4530 static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len,
4531                              struct cpumask *new_mask)
4532 {
4533         if (len < cpumask_size())
4534                 cpumask_clear(new_mask);
4535         else if (len > cpumask_size())
4536                 len = cpumask_size();
4537 
4538         return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0;
4539 }
4540 
4541 /**
4542  * sys_sched_setaffinity - set the cpu affinity of a process
4543  * @pid: pid of the process
4544  * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4545  * @user_mask_ptr: user-space pointer to the new cpu mask
4546  *
4547  * Return: 0 on success. An error code otherwise.
4548  */
4549 SYSCALL_DEFINE3(sched_setaffinity, pid_t, pid, unsigned int, len,
4550                 unsigned long __user *, user_mask_ptr)
4551 {
4552         cpumask_var_t new_mask;
4553         int retval;
4554 
4555         if (!alloc_cpumask_var(&new_mask, GFP_KERNEL))
4556                 return -ENOMEM;
4557 
4558         retval = get_user_cpu_mask(user_mask_ptr, len, new_mask);
4559         if (retval == 0)
4560                 retval = sched_setaffinity(pid, new_mask);
4561         free_cpumask_var(new_mask);
4562         return retval;
4563 }
4564 
4565 long sched_getaffinity(pid_t pid, struct cpumask *mask)
4566 {
4567         struct task_struct *p;
4568         unsigned long flags;
4569         int retval;
4570 
4571         rcu_read_lock();
4572 
4573         retval = -ESRCH;
4574         p = find_process_by_pid(pid);
4575         if (!p)
4576                 goto out_unlock;
4577 
4578         retval = security_task_getscheduler(p);
4579         if (retval)
4580                 goto out_unlock;
4581 
4582         raw_spin_lock_irqsave(&p->pi_lock, flags);
4583         cpumask_and(mask, &p->cpus_allowed, cpu_active_mask);
4584         raw_spin_unlock_irqrestore(&p->pi_lock, flags);
4585 
4586 out_unlock:
4587         rcu_read_unlock();
4588 
4589         return retval;
4590 }
4591 
4592 /**
4593  * sys_sched_getaffinity - get the cpu affinity of a process
4594  * @pid: pid of the process
4595  * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4596  * @user_mask_ptr: user-space pointer to hold the current cpu mask
4597  *
4598  * Return: 0 on success. An error code otherwise.
4599  */
4600 SYSCALL_DEFINE3(sched_getaffinity, pid_t, pid, unsigned int, len,
4601                 unsigned long __user *, user_mask_ptr)
4602 {
4603         int ret;
4604         cpumask_var_t mask;
4605 
4606         if ((len * BITS_PER_BYTE) < nr_cpu_ids)
4607                 return -EINVAL;
4608         if (len & (sizeof(unsigned long)-1))
4609                 return -EINVAL;
4610 
4611         if (!alloc_cpumask_var(&mask, GFP_KERNEL))
4612                 return -ENOMEM;
4613 
4614         ret = sched_getaffinity(pid, mask);
4615         if (ret == 0) {
4616                 size_t retlen = min_t(size_t, len, cpumask_size());
4617 
4618                 if (copy_to_user(user_mask_ptr, mask, retlen))
4619                         ret = -EFAULT;
4620                 else
4621                         ret = retlen;
4622         }
4623         free_cpumask_var(mask);
4624 
4625         return ret;
4626 }
4627 
4628 /**
4629  * sys_sched_yield - yield the current processor to other threads.
4630  *
4631  * This function yields the current CPU to other tasks. If there are no
4632  * other threads running on this CPU then this function will return.
4633  *
4634  * Return: 0.
4635  */
4636 SYSCALL_DEFINE0(sched_yield)
4637 {
4638         struct rq *rq = this_rq_lock();
4639 
4640         schedstat_inc(rq, yld_count);
4641         current->sched_class->yield_task(rq);
4642 
4643         /*
4644          * Since we are going to call schedule() anyway, there's
4645          * no need to preempt or enable interrupts:
4646          */
4647         __release(rq->lock);
4648         spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
4649         do_raw_spin_unlock(&rq->lock);
4650         sched_preempt_enable_no_resched();
4651 
4652         schedule();
4653 
4654         return 0;
4655 }
4656 
4657 int __sched _cond_resched(void)
4658 {
4659         if (should_resched(0)) {
4660                 preempt_schedule_common();
4661                 return 1;
4662         }
4663         return 0;
4664 }
4665 EXPORT_SYMBOL(_cond_resched);
4666 
4667 /*
4668  * __cond_resched_lock() - if a reschedule is pending, drop the given lock,
4669  * call schedule, and on return reacquire the lock.
4670  *
4671  * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
4672  * operations here to prevent schedule() from being called twice (once via
4673  * spin_unlock(), once by hand).
4674  */
4675 int __cond_resched_lock(spinlock_t *lock)
4676 {
4677         int resched = should_resched(PREEMPT_LOCK_OFFSET);
4678         int ret = 0;
4679 
4680         lockdep_assert_held(lock);
4681 
4682         if (spin_needbreak(lock) || resched) {
4683                 spin_unlock(lock);
4684                 if (resched)
4685                         preempt_schedule_common();
4686                 else
4687                         cpu_relax();
4688                 ret = 1;
4689                 spin_lock(lock);
4690         }
4691         return ret;
4692 }
4693 EXPORT_SYMBOL(__cond_resched_lock);
4694 
4695 int __sched __cond_resched_softirq(void)
4696 {
4697         BUG_ON(!in_softirq());
4698 
4699         if (should_resched(SOFTIRQ_DISABLE_OFFSET)) {
4700                 local_bh_enable();
4701                 preempt_schedule_common();
4702                 local_bh_disable();
4703                 return 1;
4704         }
4705         return 0;
4706 }
4707 EXPORT_SYMBOL(__cond_resched_softirq);
4708 
4709 /**
4710  * yield - yield the current processor to other threads.
4711  *
4712  * Do not ever use this function, there's a 99% chance you're doing it wrong.
4713  *
4714  * The scheduler is at all times free to pick the calling task as the most
4715  * eligible task to run, if removing the yield() call from your code breaks
4716  * it, its already broken.
4717  *
4718  * Typical broken usage is:
4719  *
4720  * while (!event)
4721  *      yield();
4722  *
4723  * where one assumes that yield() will let 'the other' process run that will
4724  * make event true. If the current task is a SCHED_FIFO task that will never
4725  * happen. Never use yield() as a progress guarantee!!
4726  *
4727  * If you want to use yield() to wait for something, use wait_event().
4728  * If you want to use yield() to be 'nice' for others, use cond_resched().
4729  * If you still want to use yield(), do not!
4730  */
4731 void __sched yield(void)
4732 {
4733         set_current_state(TASK_RUNNING);
4734         sys_sched_yield();
4735 }
4736 EXPORT_SYMBOL(yield);
4737 
4738 /**
4739  * yield_to - yield the current processor to another thread in
4740  * your thread group, or accelerate that thread toward the
4741  * processor it's on.
4742  * @p: target task
4743  * @preempt: whether task preemption is allowed or not
4744  *
4745  * It's the caller's job to ensure that the target task struct
4746  * can't go away on us before we can do any checks.
4747  *
4748  * Return:
4749  *      true (>0) if we indeed boosted the target task.
4750  *      false (0) if we failed to boost the target.
4751  *      -ESRCH if there's no task to yield to.
4752  */
4753 int __sched yield_to(struct task_struct *p, bool preempt)
4754 {
4755         struct task_struct *curr = current;
4756         struct rq *rq, *p_rq;
4757         unsigned long flags;
4758         int yielded = 0;
4759 
4760         local_irq_save(flags);
4761         rq = this_rq();
4762 
4763 again:
4764         p_rq = task_rq(p);
4765         /*
4766          * If we're the only runnable task on the rq and target rq also
4767          * has only one task, there's absolutely no point in yielding.
4768          */
4769         if (rq->nr_running == 1 && p_rq->nr_running == 1) {
4770                 yielded = -ESRCH;
4771                 goto out_irq;
4772         }
4773 
4774         double_rq_lock(rq, p_rq);
4775         if (task_rq(p) != p_rq) {
4776                 double_rq_unlock(rq, p_rq);
4777                 goto again;
4778         }
4779 
4780         if (!curr->sched_class->yield_to_task)
4781                 goto out_unlock;
4782 
4783         if (curr->sched_class != p->sched_class)
4784                 goto out_unlock;
4785 
4786         if (task_running(p_rq, p) || p->state)
4787                 goto out_unlock;
4788 
4789         yielded = curr->sched_class->yield_to_task(rq, p, preempt);
4790         if (yielded) {
4791                 schedstat_inc(rq, yld_count);
4792                 /*
4793                  * Make p's CPU reschedule; pick_next_entity takes care of
4794                  * fairness.
4795                  */
4796                 if (preempt && rq != p_rq)
4797                         resched_curr(p_rq);
4798         }
4799 
4800 out_unlock:
4801         double_rq_unlock(rq, p_rq);
4802 out_irq:
4803         local_irq_restore(flags);
4804 
4805         if (yielded > 0)
4806                 schedule();
4807 
4808         return yielded;
4809 }
4810 EXPORT_SYMBOL_GPL(yield_to);
4811 
4812 /*
4813  * This task is about to go to sleep on IO. Increment rq->nr_iowait so
4814  * that process accounting knows that this is a task in IO wait state.
4815  */
4816 long __sched io_schedule_timeout(long timeout)
4817 {
4818         int old_iowait = current->in_iowait;
4819         struct rq *rq;
4820         long ret;
4821 
4822         current->in_iowait = 1;
4823         blk_schedule_flush_plug(current);
4824 
4825         delayacct_blkio_start();
4826         rq = raw_rq();
4827         atomic_inc(&rq->nr_iowait);
4828         ret = schedule_timeout(timeout);
4829         current->in_iowait = old_iowait;
4830         atomic_dec(&rq->nr_iowait);
4831         delayacct_blkio_end();
4832 
4833         return ret;
4834 }
4835 EXPORT_SYMBOL(io_schedule_timeout);
4836 
4837 /**
4838  * sys_sched_get_priority_max - return maximum RT priority.
4839  * @policy: scheduling class.
4840  *
4841  * Return: On success, this syscall returns the maximum
4842  * rt_priority that can be used by a given scheduling class.
4843  * On failure, a negative error code is returned.
4844  */
4845 SYSCALL_DEFINE1(sched_get_priority_max, int, policy)
4846 {
4847         int ret = -EINVAL;
4848 
4849         switch (policy) {
4850         case SCHED_FIFO:
4851         case SCHED_RR:
4852                 ret = MAX_USER_RT_PRIO-1;
4853                 break;
4854         case SCHED_DEADLINE:
4855         case SCHED_NORMAL:
4856         case SCHED_BATCH:
4857         case SCHED_IDLE:
4858                 ret = 0;
4859                 break;
4860         }
4861         return ret;
4862 }
4863 
4864 /**
4865  * sys_sched_get_priority_min - return minimum RT priority.
4866  * @policy: scheduling class.
4867  *
4868  * Return: On success, this syscall returns the minimum
4869  * rt_priority that can be used by a given scheduling class.
4870  * On failure, a negative error code is returned.
4871  */
4872 SYSCALL_DEFINE1(sched_get_priority_min, int, policy)
4873 {
4874         int ret = -EINVAL;
4875 
4876         switch (policy) {
4877         case SCHED_FIFO:
4878         case SCHED_RR:
4879                 ret = 1;
4880                 break;
4881         case SCHED_DEADLINE:
4882         case SCHED_NORMAL:
4883         case SCHED_BATCH:
4884         case SCHED_IDLE:
4885                 ret = 0;
4886         }
4887         return ret;
4888 }
4889 
4890 /**
4891  * sys_sched_rr_get_interval - return the default timeslice of a process.
4892  * @pid: pid of the process.
4893  * @interval: userspace pointer to the timeslice value.
4894  *
4895  * this syscall writes the default timeslice value of a given process
4896  * into the user-space timespec buffer. A value of '' means infinity.
4897  *
4898  * Return: On success, 0 and the timeslice is in @interval. Otherwise,
4899  * an error code.
4900  */
4901 SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid,
4902                 struct timespec __user *, interval)
4903 {
4904         struct task_struct *p;
4905         unsigned int time_slice;
4906         unsigned long flags;
4907         struct rq *rq;
4908         int retval;
4909         struct timespec t;
4910 
4911         if (pid < 0)
4912                 return -EINVAL;
4913 
4914         retval = -ESRCH;
4915         rcu_read_lock();
4916         p = find_process_by_pid(pid);
4917         if (!p)
4918                 goto out_unlock;
4919 
4920         retval = security_task_getscheduler(p);
4921         if (retval)
4922                 goto out_unlock;
4923 
4924         rq = task_rq_lock(p, &flags);
4925         time_slice = 0;
4926         if (p->sched_class->get_rr_interval)
4927                 time_slice = p->sched_class->get_rr_interval(rq, p);
4928         task_rq_unlock(rq, p, &flags);
4929 
4930         rcu_read_unlock();
4931         jiffies_to_timespec(time_slice, &t);
4932         retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0;
4933         return retval;
4934 
4935 out_unlock:
4936         rcu_read_unlock();
4937         return retval;
4938 }
4939 
4940 static const char stat_nam[] = TASK_STATE_TO_CHAR_STR;
4941 
4942 void sched_show_task(struct task_struct *p)
4943 {
4944         unsigned long free = 0;
4945         int ppid;
4946         unsigned long state = p->state;
4947 
4948         if (state)
4949                 state = __ffs(state) + 1;
4950         printk(KERN_INFO "%-15.15s %c", p->comm,
4951                 state < sizeof(stat_nam) - 1 ? stat_nam[state] : '?');
4952 #if BITS_PER_LONG == 32
4953         if (state == TASK_RUNNING)
4954                 printk(KERN_CONT " running  ");
4955         else
4956                 printk(KERN_CONT " %08lx ", thread_saved_pc(p));
4957 #else
4958         if (state == TASK_RUNNING)
4959                 printk(KERN_CONT "  running task    ");
4960         else
4961                 printk(KERN_CONT " %016lx ", thread_saved_pc(p));
4962 #endif
4963 #ifdef CONFIG_DEBUG_STACK_USAGE
4964         free = stack_not_used(p);
4965 #endif
4966         ppid = 0;
4967         rcu_read_lock();
4968         if (pid_alive(p))
4969                 ppid = task_pid_nr(rcu_dereference(p->real_parent));
4970         rcu_read_unlock();
4971         printk(KERN_CONT "%5lu %5d %6d 0x%08lx\n", free,
4972                 task_pid_nr(p), ppid,
4973                 (unsigned long)task_thread_info(p)->flags);
4974 
4975         print_worker_info(KERN_INFO, p);
4976         show_stack(p, NULL);
4977 }
4978 
4979 void show_state_filter(unsigned long state_filter)
4980 {
4981         struct task_struct *g, *p;
4982 
4983 #if BITS_PER_LONG == 32
4984         printk(KERN_INFO
4985                 "  task                PC stack   pid father\n");
4986 #else
4987         printk(KERN_INFO
4988                 "  task                        PC stack   pid father\n");
4989 #endif
4990         rcu_read_lock();
4991         for_each_process_thread(g, p) {
4992                 /*
4993                  * reset the NMI-timeout, listing all files on a slow
4994                  * console might take a lot of time:
4995                  */
4996                 touch_nmi_watchdog();
4997                 if (!state_filter || (p->state & state_filter))
4998                         sched_show_task(p);
4999         }
5000 
5001         touch_all_softlockup_watchdogs();
5002 
5003 #ifdef CONFIG_SCHED_DEBUG
5004         sysrq_sched_debug_show();
5005 #endif
5006         rcu_read_unlock();
5007         /*
5008          * Only show locks if all tasks are dumped:
5009          */
5010         if (!state_filter)
5011                 debug_show_all_locks();
5012 }
5013 
5014 void init_idle_bootup_task(struct task_struct *idle)
5015 {
5016         idle->sched_class = &idle_sched_class;
5017 }
5018 
5019 /**
5020  * init_idle - set up an idle thread for a given CPU
5021  * @idle: task in question
5022  * @cpu: cpu the idle task belongs to
5023  *
5024  * NOTE: this function does not set the idle thread's NEED_RESCHED
5025  * flag, to make booting more robust.
5026  */
5027 void init_idle(struct task_struct *idle, int cpu)
5028 {
5029         struct rq *rq = cpu_rq(cpu);
5030         unsigned long flags;
5031 
5032         raw_spin_lock_irqsave(&idle->pi_lock, flags);
5033         raw_spin_lock(&rq->lock);
5034 
5035         __sched_fork(0, idle);
5036         idle->state = TASK_RUNNING;
5037         idle->se.exec_start = sched_clock();
5038 
5039         kasan_unpoison_task_stack(idle);
5040 
5041 #ifdef CONFIG_SMP
5042         /*
5043          * Its possible that init_idle() gets called multiple times on a task,
5044          * in that case do_set_cpus_allowed() will not do the right thing.
5045          *
5046          * And since this is boot we can forgo the serialization.
5047          */
5048         set_cpus_allowed_common(idle, cpumask_of(cpu));
5049 #endif
5050         /*
5051          * We're having a chicken and egg problem, even though we are
5052          * holding rq->lock, the cpu isn't yet set to this cpu so the
5053          * lockdep check in task_group() will fail.
5054          *
5055          * Similar case to sched_fork(). / Alternatively we could
5056          * use task_rq_lock() here and obtain the other rq->lock.
5057          *
5058          * Silence PROVE_RCU
5059          */
5060         rcu_read_lock();
5061         __set_task_cpu(idle, cpu);
5062         rcu_read_unlock();
5063 
5064         rq->curr = rq->idle = idle;
5065         idle->on_rq = TASK_ON_RQ_QUEUED;
5066 #ifdef CONFIG_SMP
5067         idle->on_cpu = 1;
5068 #endif
5069         raw_spin_unlock(&rq->lock);
5070         raw_spin_unlock_irqrestore(&idle->pi_lock, flags);
5071 
5072         /* Set the preempt count _outside_ the spinlocks! */
5073         init_idle_preempt_count(idle, cpu);
5074 
5075         /*
5076          * The idle tasks have their own, simple scheduling class:
5077          */
5078         idle->sched_class = &idle_sched_class;
5079         ftrace_graph_init_idle_task(idle, cpu);
5080         vtime_init_idle(idle, cpu);
5081 #ifdef CONFIG_SMP
5082         sprintf(idle->comm, "%s/%d", INIT_TASK_COMM, cpu);
5083 #endif
5084 }
5085 
5086 int cpuset_cpumask_can_shrink(const struct cpumask *cur,
5087                               const struct cpumask *trial)
5088 {
5089         int ret = 1, trial_cpus;
5090         struct dl_bw *cur_dl_b;
5091         unsigned long flags;
5092 
5093         if (!cpumask_weight(cur))
5094                 return ret;
5095 
5096         rcu_read_lock_sched();
5097         cur_dl_b = dl_bw_of(cpumask_any(cur));
5098         trial_cpus = cpumask_weight(trial);
5099 
5100         raw_spin_lock_irqsave(&cur_dl_b->lock, flags);
5101         if (cur_dl_b->bw != -1 &&
5102             cur_dl_b->bw * trial_cpus < cur_dl_b->total_bw)
5103                 ret = 0;
5104         raw_spin_unlock_irqrestore(&cur_dl_b->lock, flags);
5105         rcu_read_unlock_sched();
5106 
5107         return ret;
5108 }
5109 
5110 int task_can_attach(struct task_struct *p,
5111                     const struct cpumask *cs_cpus_allowed)
5112 {
5113         int ret = 0;
5114 
5115         /*
5116          * Kthreads which disallow setaffinity shouldn't be moved
5117          * to a new cpuset; we don't want to change their cpu
5118          * affinity and isolating such threads by their set of
5119          * allowed nodes is unnecessary.  Thus, cpusets are not
5120          * applicable for such threads.  This prevents checking for
5121          * success of set_cpus_allowed_ptr() on all attached tasks
5122          * before cpus_allowed may be changed.
5123          */
5124         if (p->flags & PF_NO_SETAFFINITY) {
5125                 ret = -EINVAL;
5126                 goto out;
5127         }
5128 
5129 #ifdef CONFIG_SMP
5130         if (dl_task(p) && !cpumask_intersects(task_rq(p)->rd->span,
5131                                               cs_cpus_allowed)) {
5132                 unsigned int dest_cpu = cpumask_any_and(cpu_active_mask,
5133                                                         cs_cpus_allowed);
5134                 struct dl_bw *dl_b;
5135                 bool overflow;
5136                 int cpus;
5137                 unsigned long flags;
5138 
5139                 rcu_read_lock_sched();
5140                 dl_b = dl_bw_of(dest_cpu);
5141                 raw_spin_lock_irqsave(&dl_b->lock, flags);
5142                 cpus = dl_bw_cpus(dest_cpu);
5143                 overflow = __dl_overflow(dl_b, cpus, 0, p->dl.dl_bw);
5144                 if (overflow)
5145                         ret = -EBUSY;
5146                 else {
5147                         /*
5148                          * We reserve space for this task in the destination
5149                          * root_domain, as we can't fail after this point.
5150                          * We will free resources in the source root_domain
5151                          * later on (see set_cpus_allowed_dl()).
5152                          */
5153                         __dl_add(dl_b, p->dl.dl_bw);
5154                 }
5155                 raw_spin_unlock_irqrestore(&dl_b->lock, flags);
5156                 rcu_read_unlock_sched();
5157 
5158         }
5159 #endif
5160 out:
5161         return ret;
5162 }
5163 
5164 #ifdef CONFIG_SMP
5165 
5166 #ifdef CONFIG_NUMA_BALANCING
5167 /* Migrate current task p to target_cpu */
5168 int migrate_task_to(struct task_struct *p, int target_cpu)
5169 {
5170         struct migration_arg arg = { p, target_cpu };
5171         int curr_cpu = task_cpu(p);
5172 
5173         if (curr_cpu == target_cpu)
5174                 return 0;
5175 
5176         if (!cpumask_test_cpu(target_cpu, tsk_cpus_allowed(p)))
5177                 return -EINVAL;
5178 
5179         /* TODO: This is not properly updating schedstats */
5180 
5181         trace_sched_move_numa(p, curr_cpu, target_cpu);
5182         return stop_one_cpu(curr_cpu, migration_cpu_stop, &arg);
5183 }
5184 
5185 /*
5186  * Requeue a task on a given node and accurately track the number of NUMA
5187  * tasks on the runqueues
5188  */
5189 void sched_setnuma(struct task_struct *p, int nid)
5190 {
5191         struct rq *rq;
5192         unsigned long flags;
5193         bool queued, running;
5194 
5195         rq = task_rq_lock(p, &flags);
5196         queued = task_on_rq_queued(p);
5197         running = task_current(rq, p);
5198 
5199         if (queued)
5200                 dequeue_task(rq, p, DEQUEUE_SAVE);
5201         if (running)
5202                 put_prev_task(rq, p);
5203 
5204         p->numa_preferred_nid = nid;
5205 
5206         if (running)
5207                 p->sched_class->set_curr_task(rq);
5208         if (queued)
5209                 enqueue_task(rq, p, ENQUEUE_RESTORE);
5210         task_rq_unlock(rq, p, &flags);
5211 }
5212 #endif /* CONFIG_NUMA_BALANCING */
5213 
5214 #ifdef CONFIG_HOTPLUG_CPU
5215 /*
5216  * Ensures that the idle task is using init_mm right before its cpu goes
5217  * offline.
5218  */
5219 void idle_task_exit(void)
5220 {
5221         struct mm_struct *mm = current->active_mm;
5222 
5223         BUG_ON(cpu_online(smp_processor_id()));
5224 
5225         if (mm != &init_mm) {
5226                 switch_mm(mm, &init_mm, current);
5227                 finish_arch_post_lock_switch();
5228         }
5229         mmdrop(mm);
5230 }
5231 
5232 /*
5233  * Since this CPU is going 'away' for a while, fold any nr_active delta
5234  * we might have. Assumes we're called after migrate_tasks() so that the
5235  * nr_active count is stable.
5236  *
5237  * Also see the comment "Global load-average calculations".
5238  */
5239 static void calc_load_migrate(struct rq *rq)
5240 {
5241         long delta = calc_load_fold_active(rq);
5242         if (delta)
5243                 atomic_long_add(delta, &calc_load_tasks);
5244 }
5245 
5246 static void put_prev_task_fake(struct rq *rq, struct task_struct *prev)
5247 {
5248 }
5249 
5250 static const struct sched_class fake_sched_class = {
5251         .put_prev_task = put_prev_task_fake,
5252 };
5253 
5254 static struct task_struct fake_task = {
5255         /*
5256          * Avoid pull_{rt,dl}_task()
5257          */
5258         .prio = MAX_PRIO + 1,
5259         .sched_class = &fake_sched_class,
5260 };
5261 
5262 /*
5263  * Migrate all tasks from the rq, sleeping tasks will be migrated by
5264  * try_to_wake_up()->select_task_rq().
5265  *
5266  * Called with rq->lock held even though we'er in stop_machine() and
5267  * there's no concurrency possible, we hold the required locks anyway
5268  * because of lock validation efforts.
5269  */
5270 static void migrate_tasks(struct rq *dead_rq)
5271 {
5272         struct rq *rq = dead_rq;
5273         struct task_struct *next, *stop = rq->stop;
5274         int dest_cpu;
5275 
5276         /*
5277          * Fudge the rq selection such that the below task selection loop
5278          * doesn't get stuck on the currently eligible stop task.
5279          *
5280          * We're currently inside stop_machine() and the rq is either stuck
5281          * in the stop_machine_cpu_stop() loop, or we're executing this code,
5282          * either way we should never end up calling schedule() until we're
5283          * done here.
5284          */
5285         rq->stop = NULL;
5286 
5287         /*
5288          * put_prev_task() and pick_next_task() sched
5289          * class method both need to have an up-to-date
5290          * value of rq->clock[_task]
5291          */
5292         update_rq_clock(rq);
5293 
5294         for (;;) {
5295                 /*
5296                  * There's this thread running, bail when that's the only
5297                  * remaining thread.
5298                  */
5299                 if (rq->nr_running == 1)
5300                         break;
5301 
5302                 /*
5303                  * pick_next_task assumes pinned rq->lock.
5304                  */
5305                 lockdep_pin_lock(&rq->lock);
5306                 next = pick_next_task(rq, &fake_task);
5307                 BUG_ON(!next);
5308                 next->sched_class->put_prev_task(rq, next);
5309 
5310                 /*
5311                  * Rules for changing task_struct::cpus_allowed are holding
5312                  * both pi_lock and rq->lock, such that holding either
5313                  * stabilizes the mask.
5314                  *
5315                  * Drop rq->lock is not quite as disastrous as it usually is
5316                  * because !cpu_active at this point, which means load-balance
5317                  * will not interfere. Also, stop-machine.
5318                  */
5319                 lockdep_unpin_lock(&rq->lock);
5320                 raw_spin_unlock(&rq->lock);
5321                 raw_spin_lock(&next->pi_lock);
5322                 raw_spin_lock(&rq->lock);
5323 
5324                 /*
5325                  * Since we're inside stop-machine, _nothing_ should have
5326                  * changed the task, WARN if weird stuff happened, because in
5327                  * that case the above rq->lock drop is a fail too.
5328                  */
5329                 if (WARN_ON(task_rq(next) != rq || !task_on_rq_queued(next))) {
5330                         raw_spin_unlock(&next->pi_lock);
5331                         continue;
5332                 }
5333 
5334                 /* Find suitable destination for @next, with force if needed. */
5335                 dest_cpu = select_fallback_rq(dead_rq->cpu, next);
5336 
5337                 rq = __migrate_task(rq, next, dest_cpu);
5338                 if (rq != dead_rq) {
5339                         raw_spin_unlock(&rq->lock);
5340                         rq = dead_rq;
5341                         raw_spin_lock(&rq->lock);
5342                 }
5343                 raw_spin_unlock(&next->pi_lock);
5344         }
5345 
5346         rq->stop = stop;
5347 }
5348 #endif /* CONFIG_HOTPLUG_CPU */
5349 
5350 static void set_rq_online(struct rq *rq)
5351 {
5352         if (!rq->online) {
5353                 const struct sched_class *class;
5354 
5355                 cpumask_set_cpu(rq->cpu, rq->rd->online);
5356                 rq->online = 1;
5357 
5358                 for_each_class(class) {
5359                         if (class->rq_online)
5360                                 class->rq_online(rq);
5361                 }
5362         }
5363 }
5364 
5365 static void set_rq_offline(struct rq *rq)
5366 {
5367         if (rq->online) {
5368                 const struct sched_class *class;
5369 
5370                 for_each_class(class) {
5371                         if (class->rq_offline)
5372                                 class->rq_offline(rq);
5373                 }
5374 
5375                 cpumask_clear_cpu(rq->cpu, rq->rd->online);
5376                 rq->online = 0;
5377         }
5378 }
5379 
5380 /*
5381  * migration_call - callback that gets triggered when a CPU is added.
5382  * Here we can start up the necessary migration thread for the new CPU.
5383  */
5384 static int
5385 migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)
5386 {
5387         int cpu = (long)hcpu;
5388         unsigned long flags;
5389         struct rq *rq = cpu_rq(cpu);
5390 
5391         switch (action & ~CPU_TASKS_FROZEN) {
5392 
5393         case CPU_UP_PREPARE:
5394                 rq->calc_load_update = calc_load_update;
5395                 account_reset_rq(rq);
5396                 break;
5397 
5398         case CPU_ONLINE:
5399                 /* Update our root-domain */
5400                 raw_spin_lock_irqsave(&rq->lock, flags);
5401                 if (rq->rd) {
5402                         BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
5403 
5404                         set_rq_online(rq);
5405                 }
5406                 raw_spin_unlock_irqrestore(&rq->lock, flags);
5407                 break;
5408 
5409 #ifdef CONFIG_HOTPLUG_CPU
5410         case CPU_DYING:
5411                 sched_ttwu_pending();
5412                 /* Update our root-domain */
5413                 raw_spin_lock_irqsave(&rq->lock, flags);
5414                 if (rq->rd) {
5415                         BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
5416                         set_rq_offline(rq);
5417                 }
5418                 migrate_tasks(rq);
5419                 BUG_ON(rq->nr_running != 1); /* the migration thread */
5420                 raw_spin_unlock_irqrestore(&rq->lock, flags);
5421                 break;
5422 
5423         case CPU_DEAD:
5424                 calc_load_migrate(rq);
5425                 break;
5426 #endif
5427         }
5428 
5429         update_max_interval();
5430 
5431         return NOTIFY_OK;
5432 }
5433 
5434 /*
5435  * Register at high priority so that task migration (migrate_all_tasks)
5436  * happens before everything else.  This has to be lower priority than
5437  * the notifier in the perf_event subsystem, though.
5438  */
5439 static struct notifier_block migration_notifier = {
5440         .notifier_call = migration_call,
5441         .priority = CPU_PRI_MIGRATION,
5442 };
5443 
5444 static void set_cpu_rq_start_time(void)
5445 {
5446         int cpu = smp_processor_id();
5447         struct rq *rq = cpu_rq(cpu);
5448         rq->age_stamp = sched_clock_cpu(cpu);
5449 }
5450 
5451 static int sched_cpu_active(struct notifier_block *nfb,
5452                                       unsigned long action, void *hcpu)
5453 {
5454         int cpu = (long)hcpu;
5455 
5456         switch (action & ~CPU_TASKS_FROZEN) {
5457         case CPU_STARTING:
5458                 set_cpu_rq_start_time();
5459                 return NOTIFY_OK;
5460 
5461         case CPU_DOWN_FAILED:
5462                 set_cpu_active(cpu, true);
5463                 return NOTIFY_OK;
5464 
5465         default:
5466                 return NOTIFY_DONE;
5467         }
5468 }
5469 
5470 static int sched_cpu_inactive(struct notifier_block *nfb,
5471                                         unsigned long action, void *hcpu)
5472 {
5473         switch (action & ~CPU_TASKS_FROZEN) {
5474         case CPU_DOWN_PREPARE:
5475                 set_cpu_active((long)hcpu, false);
5476                 return NOTIFY_OK;
5477         default:
5478                 return NOTIFY_DONE;
5479         }
5480 }
5481 
5482 static int __init migration_init(void)
5483 {
5484         void *cpu = (void *)(long)smp_processor_id();
5485         int err;
5486 
5487         /* Initialize migration for the boot CPU */
5488         err = migration_call(&migration_notifier, CPU_UP_PREPARE, cpu);
5489         BUG_ON(err == NOTIFY_BAD);
5490         migration_call(&migration_notifier, CPU_ONLINE, cpu);
5491         register_cpu_notifier(&migration_notifier);
5492 
5493         /* Register cpu active notifiers */
5494         cpu_notifier(sched_cpu_active, CPU_PRI_SCHED_ACTIVE);
5495         cpu_notifier(sched_cpu_inactive, CPU_PRI_SCHED_INACTIVE);
5496 
5497         return 0;
5498 }
5499 early_initcall(migration_init);
5500 
5501 static cpumask_var_t sched_domains_tmpmask; /* sched_domains_mutex */
5502 
5503 #ifdef CONFIG_SCHED_DEBUG
5504 
5505 static __read_mostly int sched_debug_enabled;
5506 
5507 static int __init sched_debug_setup(char *str)
5508 {
5509         sched_debug_enabled = 1;
5510 
5511         return 0;
5512 }
5513 early_param("sched_debug", sched_debug_setup);
5514 
5515 static inline bool sched_debug(void)
5516 {
5517         return sched_debug_enabled;
5518 }
5519 
5520 static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level,
5521                                   struct cpumask *groupmask)
5522 {
5523         struct sched_group *group = sd->groups;
5524 
5525         cpumask_clear(groupmask);
5526 
5527         printk(KERN_DEBUG "%*s domain %d: ", level, "", level);
5528 
5529         if (!(sd->flags & SD_LOAD_BALANCE)) {
5530                 printk("does not load-balance\n");
5531                 if (sd->parent)
5532                         printk(KERN_ERR "ERROR: !SD_LOAD_BALANCE domain"
5533                                         " has parent");
5534                 return -1;
5535         }
5536 
5537         printk(KERN_CONT "span %*pbl level %s\n",
5538                cpumask_pr_args(sched_domain_span(sd)), sd->name);
5539 
5540         if (!cpumask_test_cpu(cpu, sched_domain_span(sd))) {
5541                 printk(KERN_ERR "ERROR: domain->span does not contain "
5542                                 "CPU%d\n", cpu);
5543         }
5544         if (!cpumask_test_cpu(cpu, sched_group_cpus(group))) {
5545                 printk(KERN_ERR "ERROR: domain->groups does not contain"
5546                                 " CPU%d\n", cpu);
5547         }
5548 
5549         printk(KERN_DEBUG "%*s groups:", level + 1, "");
5550         do {
5551                 if (!group) {
5552                         printk("\n");
5553                         printk(KERN_ERR "ERROR: group is NULL\n");
5554                         break;
5555                 }
5556 
5557                 if (!cpumask_weight(sched_group_cpus(group))) {
5558                         printk(KERN_CONT "\n");
5559                         printk(KERN_ERR "ERROR: empty group\n");
5560                         break;
5561                 }
5562 
5563                 if (!(sd->flags & SD_OVERLAP) &&
5564                     cpumask_intersects(groupmask, sched_group_cpus(group))) {
5565                         printk(KERN_CONT "\n");
5566                         printk(KERN_ERR "ERROR: repeated CPUs\n");
5567                         break;
5568                 }
5569 
5570                 cpumask_or(groupmask, groupmask, sched_group_cpus(group));
5571 
5572                 printk(KERN_CONT " %*pbl",
5573                        cpumask_pr_args(sched_group_cpus(group)));
5574                 if (group->sgc->capacity != SCHED_CAPACITY_SCALE) {
5575                         printk(KERN_CONT " (cpu_capacity = %d)",
5576                                 group->sgc->capacity);
5577                 }
5578 
5579                 group = group->next;
5580         } while (group != sd->groups);
5581         printk(KERN_CONT "\n");
5582 
5583         if (!cpumask_equal(sched_domain_span(sd), groupmask))
5584                 printk(KERN_ERR "ERROR: groups don't span domain->span\n");
5585 
5586         if (sd->parent &&
5587             !cpumask_subset(groupmask, sched_domain_span(sd->parent)))
5588                 printk(KERN_ERR "ERROR: parent span is not a superset "
5589                         "of domain->span\n");
5590         return 0;
5591 }
5592 
5593 static void sched_domain_debug(struct sched_domain *sd, int cpu)
5594 {
5595         int level = 0;
5596 
5597         if (!sched_debug_enabled)
5598                 return;
5599 
5600         if (!sd) {
5601                 printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu);
5602                 return;
5603         }
5604 
5605         printk(KERN_DEBUG "CPU%d attaching sched-domain:\n", cpu);
5606 
5607         for (;;) {
5608                 if (sched_domain_debug_one(sd, cpu, level, sched_domains_tmpmask))
5609                         break;
5610                 level++;
5611                 sd = sd->parent;
5612                 if (!sd)
5613                         break;
5614         }
5615 }
5616 #else /* !CONFIG_SCHED_DEBUG */
5617 # define sched_domain_debug(sd, cpu) do { } while (0)
5618 static inline bool sched_debug(void)
5619 {
5620         return false;
5621 }
5622 #endif /* CONFIG_SCHED_DEBUG */
5623 
5624 static int sd_degenerate(struct sched_domain *sd)
5625 {
5626         if (cpumask_weight(sched_domain_span(sd)) == 1)
5627                 return 1;
5628 
5629         /* Following flags need at least 2 groups */
5630         if (sd->flags & (SD_LOAD_BALANCE |
5631                          SD_BALANCE_NEWIDLE |
5632                          SD_BALANCE_FORK |
5633                          SD_BALANCE_EXEC |
5634                          SD_SHARE_CPUCAPACITY |
5635                          SD_SHARE_PKG_RESOURCES |
5636                          SD_SHARE_POWERDOMAIN)) {
5637                 if (sd->groups != sd->groups->next)
5638                         return 0;
5639         }
5640 
5641         /* Following flags don't use groups */
5642         if (sd->flags & (SD_WAKE_AFFINE))
5643                 return 0;
5644 
5645         return 1;
5646 }
5647 
5648 static int
5649 sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent)
5650 {
5651         unsigned long cflags = sd->flags, pflags = parent->flags;
5652 
5653         if (sd_degenerate(parent))
5654                 return 1;
5655 
5656         if (!cpumask_equal(sched_domain_span(sd), sched_domain_span(parent)))
5657                 return 0;
5658 
5659         /* Flags needing groups don't count if only 1 group in parent */
5660         if (parent->groups == parent->groups->next) {
5661                 pflags &= ~(SD_LOAD_BALANCE |
5662                                 SD_BALANCE_NEWIDLE |
5663                                 SD_BALANCE_FORK |
5664                                 SD_BALANCE_EXEC |
5665                                 SD_SHARE_CPUCAPACITY |
5666                                 SD_SHARE_PKG_RESOURCES |
5667                                 SD_PREFER_SIBLING |
5668                                 SD_SHARE_POWERDOMAIN);
5669                 if (nr_node_ids == 1)
5670                         pflags &= ~SD_SERIALIZE;
5671         }
5672         if (~cflags & pflags)
5673                 return 0;
5674 
5675         return 1;
5676 }
5677 
5678 static void free_rootdomain(struct rcu_head *rcu)
5679 {
5680         struct root_domain *rd = container_of(rcu, struct root_domain, rcu);
5681 
5682         cpupri_cleanup(&rd->cpupri);
5683         cpudl_cleanup(&rd->cpudl);
5684         free_cpumask_var(rd->dlo_mask);
5685         free_cpumask_var(rd->rto_mask);
5686         free_cpumask_var(rd->online);
5687         free_cpumask_var(rd->span);
5688         kfree(rd);
5689 }
5690 
5691 static void rq_attach_root(struct rq *rq, struct root_domain *rd)
5692 {
5693         struct root_domain *old_rd = NULL;
5694         unsigned long flags;
5695 
5696         raw_spin_lock_irqsave(&rq->lock, flags);
5697 
5698         if (rq->rd) {
5699                 old_rd = rq->rd;
5700 
5701                 if (cpumask_test_cpu(rq->cpu, old_rd->online))
5702                         set_rq_offline(rq);
5703 
5704                 cpumask_clear_cpu(rq->cpu, old_rd->span);
5705 
5706                 /*
5707                  * If we dont want to free the old_rd yet then
5708                  * set old_rd to NULL to skip the freeing later
5709                  * in this function:
5710                  */
5711                 if (!atomic_dec_and_test(&old_rd->refcount))
5712                         old_rd = NULL;
5713         }
5714 
5715         atomic_inc(&rd->refcount);
5716         rq->rd = rd;
5717 
5718         cpumask_set_cpu(rq->cpu, rd->span);
5719         if (cpumask_test_cpu(rq->cpu, cpu_active_mask))
5720                 set_rq_online(rq);
5721 
5722         raw_spin_unlock_irqrestore(&rq->lock, flags);
5723 
5724         if (old_rd)
5725                 call_rcu_sched(&old_rd->rcu, free_rootdomain);
5726 }
5727 
5728 static int init_rootdomain(struct root_domain *rd)
5729 {
5730         memset(rd, 0, sizeof(*rd));
5731 
5732         if (!zalloc_cpumask_var(&rd->span, GFP_KERNEL))
5733                 goto out;
5734         if (!zalloc_cpumask_var(&rd->online, GFP_KERNEL))
5735                 goto free_span;
5736         if (!zalloc_cpumask_var(&rd->dlo_mask, GFP_KERNEL))
5737                 goto free_online;
5738         if (!zalloc_cpumask_var(&rd->rto_mask, GFP_KERNEL))
5739                 goto free_dlo_mask;
5740 
5741         init_dl_bw(&rd->dl_bw);
5742         if (cpudl_init(&rd->cpudl) != 0)
5743                 goto free_dlo_mask;
5744 
5745         if (cpupri_init(&rd->cpupri) != 0)
5746                 goto free_rto_mask;
5747         return 0;
5748 
5749 free_rto_mask:
5750         free_cpumask_var(rd->rto_mask);
5751 free_dlo_mask:
5752         free_cpumask_var(rd->dlo_mask);
5753 free_online:
5754         free_cpumask_var(rd->online);
5755 free_span:
5756         free_cpumask_var(rd->span);
5757 out:
5758         return -ENOMEM;
5759 }
5760 
5761 /*
5762  * By default the system creates a single root-domain with all cpus as
5763  * members (mimicking the global state we have today).
5764  */
5765 struct root_domain def_root_domain;
5766 
5767 static void init_defrootdomain(void)
5768 {
5769         init_rootdomain(&def_root_domain);
5770 
5771         atomic_set(&def_root_domain.refcount, 1);
5772 }
5773 
5774 static struct root_domain *alloc_rootdomain(void)
5775 {
5776         struct root_domain *rd;
5777 
5778         rd = kmalloc(sizeof(*rd), GFP_KERNEL);
5779         if (!rd)
5780                 return NULL;
5781 
5782         if (init_rootdomain(rd) != 0) {
5783                 kfree(rd);
5784                 return NULL;
5785         }
5786 
5787         return rd;
5788 }
5789 
5790 static void free_sched_groups(struct sched_group *sg, int free_sgc)
5791 {
5792         struct sched_group *tmp, *first;
5793 
5794         if (!sg)
5795                 return;
5796 
5797         first = sg;
5798         do {
5799                 tmp = sg->next;
5800 
5801                 if (free_sgc && atomic_dec_and_test(&sg->sgc->ref))
5802                         kfree(sg->sgc);
5803 
5804                 kfree(sg);
5805                 sg = tmp;
5806         } while (sg != first);
5807 }
5808 
5809 static void free_sched_domain(struct rcu_head *rcu)
5810 {
5811         struct sched_domain *sd = container_of(rcu, struct sched_domain, rcu);
5812 
5813         /*
5814          * If its an overlapping domain it has private groups, iterate and
5815          * nuke them all.
5816          */
5817         if (sd->flags & SD_OVERLAP) {
5818                 free_sched_groups(sd->groups, 1);
5819         } else if (atomic_dec_and_test(&sd->groups->ref)) {
5820                 kfree(sd->groups->sgc);
5821                 kfree(sd->groups);
5822         }
5823         kfree(sd);
5824 }
5825 
5826 static void destroy_sched_domain(struct sched_domain *sd, int cpu)
5827 {
5828         call_rcu(&sd->rcu, free_sched_domain);
5829 }
5830 
5831 static void destroy_sched_domains(struct sched_domain *sd, int cpu)
5832 {
5833         for (; sd; sd = sd->parent)
5834                 destroy_sched_domain(sd, cpu);
5835 }
5836 
5837 /*
5838  * Keep a special pointer to the highest sched_domain that has
5839  * SD_SHARE_PKG_RESOURCE set (Last Level Cache Domain) for this
5840  * allows us to avoid some pointer chasing select_idle_sibling().
5841  *
5842  * Also keep a unique ID per domain (we use the first cpu number in
5843  * the cpumask of the domain), this allows us to quickly tell if
5844  * two cpus are in the same cache domain, see cpus_share_cache().
5845  */
5846 DEFINE_PER_CPU(struct sched_domain *, sd_llc);
5847 DEFINE_PER_CPU(int, sd_llc_size);
5848 DEFINE_PER_CPU(int, sd_llc_id);
5849 DEFINE_PER_CPU(struct sched_domain *, sd_numa);
5850 DEFINE_PER_CPU(struct sched_domain *, sd_busy);
5851 DEFINE_PER_CPU(struct sched_domain *, sd_asym);
5852 
5853 static void update_top_cache_domain(int cpu)
5854 {
5855         struct sched_domain *sd;
5856         struct sched_domain *busy_sd = NULL;
5857         int id = cpu;
5858         int size = 1;
5859 
5860         sd = highest_flag_domain(cpu, SD_SHARE_PKG_RESOURCES);
5861         if (sd) {
5862                 id = cpumask_first(sched_domain_span(sd));
5863                 size = cpumask_weight(sched_domain_span(sd));
5864                 busy_sd = sd->parent; /* sd_busy */
5865         }
5866         rcu_assign_pointer(per_cpu(sd_busy, cpu), busy_sd);
5867 
5868         rcu_assign_pointer(per_cpu(sd_llc, cpu), sd);
5869         per_cpu(sd_llc_size, cpu) = size;
5870         per_cpu(sd_llc_id, cpu) = id;
5871 
5872         sd = lowest_flag_domain(cpu, SD_NUMA);
5873         rcu_assign_pointer(per_cpu(sd_numa, cpu), sd);
5874 
5875         sd = highest_flag_domain(cpu, SD_ASYM_PACKING);
5876         rcu_assign_pointer(per_cpu(sd_asym, cpu), sd);
5877 }
5878 
5879 /*
5880  * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
5881  * hold the hotplug lock.
5882  */
5883 static void
5884 cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu)
5885 {
5886         struct rq *rq = cpu_rq(cpu);
5887         struct sched_domain *tmp;
5888 
5889         /* Remove the sched domains which do not contribute to scheduling. */
5890         for (tmp = sd; tmp; ) {
5891                 struct sched_domain *parent = tmp->parent;
5892                 if (!parent)
5893                         break;
5894 
5895                 if (sd_parent_degenerate(tmp, parent)) {
5896                         tmp->parent = parent->parent;
5897                         if (parent->parent)
5898                                 parent->parent->child = tmp;
5899                         /*
5900                          * Transfer SD_PREFER_SIBLING down in case of a
5901                          * degenerate parent; the spans match for this
5902                          * so the property transfers.
5903                          */
5904                         if (parent->flags & SD_PREFER_SIBLING)
5905                                 tmp->flags |= SD_PREFER_SIBLING;
5906                         destroy_sched_domain(parent, cpu);
5907                 } else
5908                         tmp = tmp->parent;
5909         }
5910 
5911         if (sd && sd_degenerate(sd)) {
5912                 tmp = sd;
5913                 sd = sd->parent;
5914                 destroy_sched_domain(tmp, cpu);
5915                 if (sd)
5916                         sd->child = NULL;
5917         }
5918 
5919         sched_domain_debug(sd, cpu);
5920 
5921         rq_attach_root(rq, rd);
5922         tmp = rq->sd;
5923         rcu_assign_pointer(rq->sd, sd);
5924         destroy_sched_domains(tmp, cpu);
5925 
5926         update_top_cache_domain(cpu);
5927 }
5928 
5929 /* Setup the mask of cpus configured for isolated domains */
5930 static int __init isolated_cpu_setup(char *str)
5931 {
5932         int ret;
5933 
5934         alloc_bootmem_cpumask_var(&cpu_isolated_map);
5935         ret = cpulist_parse(str, cpu_isolated_map);
5936         if (ret) {
5937                 pr_err("sched: Error, all isolcpus= values must be between 0 and %d\n", nr_cpu_ids);
5938                 return 0;
5939         }
5940         return 1;
5941 }
5942 __setup("isolcpus=", isolated_cpu_setup);
5943 
5944 struct s_data {
5945         struct sched_domain ** __percpu sd;
5946         struct root_domain      *rd;
5947 };
5948 
5949 enum s_alloc {
5950         sa_rootdomain,
5951         sa_sd,
5952         sa_sd_storage,
5953         sa_none,
5954 };
5955 
5956 /*
5957  * Build an iteration mask that can exclude certain CPUs from the upwards
5958  * domain traversal.
5959  *
5960  * Asymmetric node setups can result in situations where the domain tree is of
5961  * unequal depth, make sure to skip domains that already cover the entire
5962  * range.
5963  *
5964  * In that case build_sched_domains() will have terminated the iteration early
5965  * and our sibling sd spans will be empty. Domains should always include the
5966  * cpu they're built on, so check that.
5967  *
5968  */
5969 static void build_group_mask(struct sched_domain *sd, struct sched_group *sg)
5970 {
5971         const struct cpumask *span = sched_domain_span(sd);
5972         struct sd_data *sdd = sd->private;
5973         struct sched_domain *sibling;
5974         int i;
5975 
5976         for_each_cpu(i, span) {
5977                 sibling = *per_cpu_ptr(sdd->sd, i);
5978                 if (!cpumask_test_cpu(i, sched_domain_span(sibling)))
5979                         continue;
5980 
5981                 cpumask_set_cpu(i, sched_group_mask(sg));
5982         }
5983 }
5984 
5985 /*
5986  * Return the canonical balance cpu for this group, this is the first cpu
5987  * of this group that's also in the iteration mask.
5988  */
5989 int group_balance_cpu(struct sched_group *sg)
5990 {
5991         return cpumask_first_and(sched_group_cpus(sg), sched_group_mask(sg));
5992 }
5993 
5994 static int
5995 build_overlap_sched_groups(struct sched_domain *sd, int cpu)
5996 {
5997         struct sched_group *first = NULL, *last = NULL, *groups = NULL, *sg;
5998         const struct cpumask *span = sched_domain_span(sd);
5999         struct cpumask *covered = sched_domains_tmpmask;
6000         struct sd_data *sdd = sd->private;
6001         struct sched_domain *sibling;
6002         int i;
6003 
6004         cpumask_clear(covered);
6005 
6006         for_each_cpu(i, span) {
6007                 struct cpumask *sg_span;
6008 
6009                 if (cpumask_test_cpu(i, covered))
6010                         continue;
6011 
6012                 sibling = *per_cpu_ptr(sdd->sd, i);
6013 
6014                 /* See the comment near build_group_mask(). */
6015                 if (!cpumask_test_cpu(i, sched_domain_span(sibling)))
6016                         continue;
6017 
6018                 sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
6019                                 GFP_KERNEL, cpu_to_node(cpu));
6020 
6021                 if (!sg)
6022                         goto fail;
6023 
6024                 sg_span = sched_group_cpus(sg);
6025                 if (sibling->child)
6026                         cpumask_copy(sg_span, sched_domain_span(sibling->child));
6027                 else
6028                         cpumask_set_cpu(i, sg_span);
6029 
6030                 cpumask_or(covered, covered, sg_span);
6031 
6032                 sg->sgc = *per_cpu_ptr(sdd->sgc, i);
6033                 if (atomic_inc_return(&sg->sgc->ref) == 1)
6034                         build_group_mask(sd, sg);
6035 
6036                 /*
6037                  * Initialize sgc->capacity such that even if we mess up the
6038                  * domains and no possible iteration will get us here, we won't
6039                  * die on a /0 trap.
6040                  */
6041                 sg->sgc->capacity = SCHED_CAPACITY_SCALE * cpumask_weight(sg_span);
6042 
6043                 /*
6044                  * Make sure the first group of this domain contains the
6045                  * canonical balance cpu. Otherwise the sched_domain iteration
6046                  * breaks. See update_sg_lb_stats().
6047                  */
6048                 if ((!groups && cpumask_test_cpu(cpu, sg_span)) ||
6049                     group_balance_cpu(sg) == cpu)
6050                         groups = sg;
6051 
6052                 if (!first)
6053                         first = sg;
6054                 if (last)
6055                         last->next = sg;
6056                 last = sg;
6057                 last->next = first;
6058         }
6059         sd->groups = groups;
6060 
6061         return 0;
6062 
6063 fail:
6064         free_sched_groups(first, 0);
6065 
6066         return -ENOMEM;
6067 }
6068 
6069 static int get_group(int cpu, struct sd_data *sdd, struct sched_group **sg)
6070 {
6071         struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu);
6072         struct sched_domain *child = sd->child;
6073 
6074         if (child)
6075                 cpu = cpumask_first(sched_domain_span(child));
6076 
6077         if (sg) {
6078                 *sg = *per_cpu_ptr(sdd->sg, cpu);
6079                 (*sg)->sgc = *per_cpu_ptr(sdd->sgc, cpu);
6080                 atomic_set(&(*sg)->sgc->ref, 1); /* for claim_allocations */
6081         }
6082 
6083         return cpu;
6084 }
6085 
6086 /*
6087  * build_sched_groups will build a circular linked list of the groups
6088  * covered by the given span, and will set each group's ->cpumask correctly,
6089  * and ->cpu_capacity to 0.
6090  *
6091  * Assumes the sched_domain tree is fully constructed
6092  */
6093 static int
6094 build_sched_groups(struct sched_domain *sd, int cpu)
6095 {
6096         struct sched_group *first = NULL, *last = NULL;
6097         struct sd_data *sdd = sd->private;
6098         const struct cpumask *span = sched_domain_span(sd);
6099         struct cpumask *covered;
6100         int i;
6101 
6102         get_group(cpu, sdd, &sd->groups);
6103         atomic_inc(&sd->groups->ref);
6104 
6105         if (cpu != cpumask_first(span))
6106                 return 0;
6107 
6108         lockdep_assert_held(&sched_domains_mutex);
6109         covered = sched_domains_tmpmask;
6110 
6111         cpumask_clear(covered);
6112 
6113         for_each_cpu(i, span) {
6114                 struct sched_group *sg;
6115                 int group, j;
6116 
6117                 if (cpumask_test_cpu(i, covered))
6118                         continue;
6119 
6120                 group = get_group(i, sdd, &sg);
6121                 cpumask_setall(sched_group_mask(sg));
6122 
6123                 for_each_cpu(j, span) {
6124                         if (get_group(j, sdd, NULL) != group)
6125                                 continue;
6126 
6127                         cpumask_set_cpu(j, covered);
6128                         cpumask_set_cpu(j, sched_group_cpus(sg));
6129                 }
6130 
6131                 if (!first)
6132                         first = sg;
6133                 if (last)
6134                         last->next = sg;
6135                 last = sg;
6136         }
6137         last->next = first;
6138 
6139         return 0;
6140 }
6141 
6142 /*
6143  * Initialize sched groups cpu_capacity.
6144  *
6145  * cpu_capacity indicates the capacity of sched group, which is used while
6146  * distributing the load between different sched groups in a sched domain.
6147  * Typically cpu_capacity for all the groups in a sched domain will be same
6148  * unless there are asymmetries in the topology. If there are asymmetries,
6149  * group having more cpu_capacity will pickup more load compared to the
6150  * group having less cpu_capacity.
6151  */
6152 static void init_sched_groups_capacity(int cpu, struct sched_domain *sd)
6153 {
6154         struct sched_group *sg = sd->groups;
6155 
6156         WARN_ON(!sg);
6157 
6158         do {
6159                 sg->group_weight = cpumask_weight(sched_group_cpus(sg));
6160                 sg = sg->next;
6161         } while (sg != sd->groups);
6162 
6163         if (cpu != group_balance_cpu(sg))
6164                 return;
6165 
6166         update_group_capacity(sd, cpu);
6167         atomic_set(&sg->sgc->nr_busy_cpus, sg->group_weight);
6168 }
6169 
6170 /*
6171  * Initializers for schedule domains
6172  * Non-inlined to reduce accumulated stack pressure in build_sched_domains()
6173  */
6174 
6175 static int default_relax_domain_level = -1;
6176 int sched_domain_level_max;
6177 
6178 static int __init setup_relax_domain_level(char *str)
6179 {
6180         if (kstrtoint(str, 0, &default_relax_domain_level))
6181                 pr_warn("Unable to set relax_domain_level\n");
6182 
6183         return 1;
6184 }
6185 __setup("relax_domain_level=", setup_relax_domain_level);
6186 
6187 static void set_domain_attribute(struct sched_domain *sd,
6188                                  struct sched_domain_attr *attr)
6189 {
6190         int request;
6191 
6192         if (!attr || attr->relax_domain_level < 0) {
6193                 if (default_relax_domain_level < 0)
6194                         return;
6195                 else
6196                         request = default_relax_domain_level;
6197         } else
6198                 request = attr->relax_domain_level;
6199         if (request < sd->level) {
6200                 /* turn off idle balance on this domain */
6201                 sd->flags &= ~(SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
6202         } else {
6203                 /* turn on idle balance on this domain */
6204                 sd->flags |= (SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
6205         }
6206 }
6207 
6208 static void __sdt_free(const struct cpumask *cpu_map);
6209 static int __sdt_alloc(const struct cpumask *cpu_map);
6210 
6211 static void __free_domain_allocs(struct s_data *d, enum s_alloc what,
6212                                  const struct cpumask *cpu_map)
6213 {
6214         switch (what) {
6215         case sa_rootdomain:
6216                 if (!atomic_read(&d->rd->refcount))
6217                         free_rootdomain(&d->rd->rcu); /* fall through */
6218         case sa_sd:
6219                 free_percpu(d->sd); /* fall through */
6220         case sa_sd_storage:
6221                 __sdt_free(cpu_map); /* fall through */
6222         case sa_none:
6223                 break;
6224         }
6225 }
6226 
6227 static enum s_alloc __visit_domain_allocation_hell(struct s_data *d,
6228                                                    const struct cpumask *cpu_map)
6229 {
6230         memset(d, 0, sizeof(*d));
6231 
6232         if (__sdt_alloc(cpu_map))
6233                 return sa_sd_storage;
6234         d->sd = alloc_percpu(struct sched_domain *);
6235         if (!d->sd)
6236                 return sa_sd_storage;
6237         d->rd = alloc_rootdomain();
6238         if (!d->rd)
6239                 return sa_sd;
6240         return sa_rootdomain;
6241 }
6242 
6243 /*
6244  * NULL the sd_data elements we've used to build the sched_domain and
6245  * sched_group structure so that the subsequent __free_domain_allocs()
6246  * will not free the data we're using.
6247  */
6248 static void claim_allocations(int cpu, struct sched_domain *sd)
6249 {
6250         struct sd_data *sdd = sd->private;
6251 
6252         WARN_ON_ONCE(*per_cpu_ptr(sdd->sd, cpu) != sd);
6253         *per_cpu_ptr(sdd->sd, cpu) = NULL;
6254 
6255         if (atomic_read(&(*per_cpu_ptr(sdd->sg, cpu))->ref))
6256                 *per_cpu_ptr(sdd->sg, cpu) = NULL;
6257 
6258         if (atomic_read(&(*per_cpu_ptr(sdd->sgc, cpu))->ref))
6259                 *per_cpu_ptr(sdd->sgc, cpu) = NULL;
6260 }
6261 
6262 #ifdef CONFIG_NUMA
6263 static int sched_domains_numa_levels;
6264 enum numa_topology_type sched_numa_topology_type;
6265 static int *sched_domains_numa_distance;
6266 int sched_max_numa_distance;
6267 static struct cpumask ***sched_domains_numa_masks;
6268 static int sched_domains_curr_level;
6269 #endif
6270 
6271 /*
6272  * SD_flags allowed in topology descriptions.
6273  *
6274  * SD_SHARE_CPUCAPACITY      - describes SMT topologies
6275  * SD_SHARE_PKG_RESOURCES - describes shared caches
6276  * SD_NUMA                - describes NUMA topologies
6277  * SD_SHARE_POWERDOMAIN   - describes shared power domain
6278  *
6279  * Odd one out:
6280  * SD_ASYM_PACKING        - describes SMT quirks
6281  */
6282 #define TOPOLOGY_SD_FLAGS               \
6283         (SD_SHARE_CPUCAPACITY |         \
6284          SD_SHARE_PKG_RESOURCES |       \
6285          SD_NUMA |                      \
6286          SD_ASYM_PACKING |              \
6287          SD_SHARE_POWERDOMAIN)
6288 
6289 static struct sched_domain *
6290 sd_init(struct sched_domain_topology_level *tl, int cpu)
6291 {
6292         struct sched_domain *sd = *per_cpu_ptr(tl->data.sd, cpu);
6293         int sd_weight, sd_flags = 0;
6294 
6295 #ifdef CONFIG_NUMA
6296         /*
6297          * Ugly hack to pass state to sd_numa_mask()...
6298          */
6299         sched_domains_curr_level = tl->numa_level;
6300 #endif
6301 
6302         sd_weight = cpumask_weight(tl->mask(cpu));
6303 
6304         if (tl->sd_flags)
6305                 sd_flags = (*tl->sd_flags)();
6306         if (WARN_ONCE(sd_flags & ~TOPOLOGY_SD_FLAGS,
6307                         "wrong sd_flags in topology description\n"))
6308                 sd_flags &= ~TOPOLOGY_SD_FLAGS;
6309 
6310         *sd = (struct sched_domain){
6311                 .min_interval           = sd_weight,
6312                 .max_interval           = 2*sd_weight,
6313                 .busy_factor            = 32,
6314                 .imbalance_pct          = 125,
6315 
6316                 .cache_nice_tries       = 0,
6317                 .busy_idx               = 0,
6318                 .idle_idx               = 0,
6319                 .newidle_idx            = 0,
6320                 .wake_idx               = 0,
6321                 .forkexec_idx           = 0,
6322 
6323                 .flags                  = 1*SD_LOAD_BALANCE
6324                                         | 1*SD_BALANCE_NEWIDLE
6325                                         | 1*SD_BALANCE_EXEC
6326                                         | 1*SD_BALANCE_FORK
6327                                         | 0*SD_BALANCE_WAKE
6328                                         | 1*SD_WAKE_AFFINE
6329                                         | 0*SD_SHARE_CPUCAPACITY
6330                                         | 0*SD_SHARE_PKG_RESOURCES
6331                                         | 0*SD_SERIALIZE
6332                                         | 0*SD_PREFER_SIBLING
6333                                         | 0*SD_NUMA
6334                                         | sd_flags
6335                                         ,
6336 
6337                 .last_balance           = jiffies,
6338                 .balance_interval       = sd_weight,
6339                 .smt_gain               = 0,
6340                 .max_newidle_lb_cost    = 0,
6341                 .next_decay_max_lb_cost = jiffies,
6342 #ifdef CONFIG_SCHED_DEBUG
6343                 .name                   = tl->name,
6344 #endif
6345         };
6346 
6347         /*
6348          * Convert topological properties into behaviour.
6349          */
6350 
6351         if (sd->flags & SD_SHARE_CPUCAPACITY) {
6352                 sd->flags |= SD_PREFER_SIBLING;
6353                 sd->imbalance_pct = 110;
6354                 sd->smt_gain = 1178; /* ~15% */
6355 
6356         } else if (sd->flags & SD_SHARE_PKG_RESOURCES) {
6357                 sd->imbalance_pct = 117;
6358                 sd->cache_nice_tries = 1;
6359                 sd->busy_idx = 2;
6360 
6361 #ifdef CONFIG_NUMA
6362         } else if (sd->flags & SD_NUMA) {
6363                 sd->cache_nice_tries = 2;
6364                 sd->busy_idx = 3;
6365                 sd->idle_idx = 2;
6366 
6367                 sd->flags |= SD_SERIALIZE;
6368                 if (sched_domains_numa_distance[tl->numa_level] > RECLAIM_DISTANCE) {
6369                         sd->flags &= ~(SD_BALANCE_EXEC |
6370                                        SD_BALANCE_FORK |
6371                                        SD_WAKE_AFFINE);
6372                 }
6373 
6374 #endif
6375         } else {
6376                 sd->flags |= SD_PREFER_SIBLING;
6377                 sd->cache_nice_tries = 1;
6378                 sd->busy_idx = 2;
6379                 sd->idle_idx = 1;
6380         }
6381 
6382         sd->private = &tl->data;
6383 
6384         return sd;
6385 }
6386 
6387 /*
6388  * Topology list, bottom-up.
6389  */
6390 static struct sched_domain_topology_level default_topology[] = {
6391 #ifdef CONFIG_SCHED_SMT
6392         { cpu_smt_mask, cpu_smt_flags, SD_INIT_NAME(SMT) },
6393 #endif
6394 #ifdef CONFIG_SCHED_MC
6395         { cpu_coregroup_mask, cpu_core_flags, SD_INIT_NAME(MC) },
6396 #endif
6397         { cpu_cpu_mask, SD_INIT_NAME(DIE) },
6398         { NULL, },
6399 };
6400 
6401 static struct sched_domain_topology_level *sched_domain_topology =
6402         default_topology;
6403 
6404 #define for_each_sd_topology(tl)                        \
6405         for (tl = sched_domain_topology; tl->mask; tl++)
6406 
6407 void set_sched_topology(struct sched_domain_topology_level *tl)
6408 {
6409         sched_domain_topology = tl;
6410 }
6411 
6412 #ifdef CONFIG_NUMA
6413 
6414 static const struct cpumask *sd_numa_mask(int cpu)
6415 {
6416         return sched_domains_numa_masks[sched_domains_curr_level][cpu_to_node(cpu)];
6417 }
6418 
6419 static void sched_numa_warn(const char *str)
6420 {
6421         static int done = false;
6422         int i,j;
6423 
6424         if (done)
6425                 return;
6426 
6427         done = true;
6428 
6429         printk(KERN_WARNING "ERROR: %s\n\n", str);
6430 
6431         for (i = 0; i < nr_node_ids; i++) {
6432                 printk(KERN_WARNING "  ");
6433                 for (j = 0; j < nr_node_ids; j++)
6434                         printk(KERN_CONT "%02d ", node_distance(i,j));
6435                 printk(KERN_CONT "\n");
6436         }
6437         printk(KERN_WARNING "\n");
6438 }
6439 
6440 bool find_numa_distance(int distance)
6441 {
6442         int i;
6443 
6444         if (distance == node_distance(0, 0))
6445                 return true;
6446 
6447         for (i = 0; i < sched_domains_numa_levels; i++) {
6448                 if (sched_domains_numa_distance[i] == distance)
6449                         return true;
6450         }
6451 
6452         return false;
6453 }
6454 
6455 /*
6456  * A system can have three types of NUMA topology:
6457  * NUMA_DIRECT: all nodes are directly connected, or not a NUMA system
6458  * NUMA_GLUELESS_MESH: some nodes reachable through intermediary nodes
6459  * NUMA_BACKPLANE: nodes can reach other nodes through a backplane
6460  *
6461  * The difference between a glueless mesh topology and a backplane
6462  * topology lies in whether communication between not directly
6463  * connected nodes goes through intermediary nodes (where programs
6464  * could run), or through backplane controllers. This affects
6465  * placement of programs.
6466  *
6467  * The type of topology can be discerned with the following tests:
6468  * - If the maximum distance between any nodes is 1 hop, the system
6469  *   is directly connected.
6470  * - If for two nodes A and B, located N > 1 hops away from each other,
6471  *   there is an intermediary node C, which is < N hops away from both
6472  *   nodes A and B, the system is a glueless mesh.
6473  */
6474 static void init_numa_topology_type(void)
6475 {
6476         int a, b, c, n;
6477 
6478         n = sched_max_numa_distance;
6479 
6480         if (sched_domains_numa_levels <= 1) {
6481                 sched_numa_topology_type = NUMA_DIRECT;
6482                 return;
6483         }
6484 
6485         for_each_online_node(a) {
6486                 for_each_online_node(b) {
6487                         /* Find two nodes furthest removed from each other. */
6488                         if (node_distance(a, b) < n)
6489                                 continue;
6490 
6491                         /* Is there an intermediary node between a and b? */
6492                         for_each_online_node(c) {
6493                                 if (node_distance(a, c) < n &&
6494                                     node_distance(b, c) < n) {
6495                                         sched_numa_topology_type =
6496                                                         NUMA_GLUELESS_MESH;
6497                                         return;
6498                                 }
6499                         }
6500 
6501                         sched_numa_topology_type = NUMA_BACKPLANE;
6502                         return;
6503                 }
6504         }
6505 }
6506 
6507 static void sched_init_numa(void)
6508 {
6509         int next_distance, curr_distance = node_distance(0, 0);
6510         struct sched_domain_topology_level *tl;
6511         int level = 0;
6512         int i, j, k;
6513 
6514         sched_domains_numa_distance = kzalloc(sizeof(int) * nr_node_ids, GFP_KERNEL);
6515         if (!sched_domains_numa_distance)
6516                 return;
6517 
6518         /*
6519          * O(nr_nodes^2) deduplicating selection sort -- in order to find the
6520          * unique distances in the node_distance() table.
6521          *
6522          * Assumes node_distance(0,j) includes all distances in
6523          * node_distance(i,j) in order to avoid cubic time.
6524          */
6525         next_distance = curr_distance;
6526         for (i = 0; i < nr_node_ids; i++) {
6527                 for (j = 0; j < nr_node_ids; j++) {
6528                         for (k = 0; k < nr_node_ids; k++) {
6529                                 int distance = node_distance(i, k);
6530 
6531                                 if (distance > curr_distance &&
6532                                     (distance < next_distance ||
6533                                      next_distance == curr_distance))
6534                                         next_distance = distance;
6535 
6536                                 /*
6537                                  * While not a strong assumption it would be nice to know
6538                                  * about cases where if node A is connected to B, B is not
6539                                  * equally connected to A.
6540                                  */
6541                                 if (sched_debug() && node_distance(k, i) != distance)
6542                                         sched_numa_warn("Node-distance not symmetric");
6543 
6544                                 if (sched_debug() && i && !find_numa_distance(distance))
6545                                         sched_numa_warn("Node-0 not representative");
6546                         }
6547                         if (next_distance != curr_distance) {
6548                                 sched_domains_numa_distance[level++] = next_distance;
6549                                 sched_domains_numa_levels = level;
6550                                 curr_distance = next_distance;
6551                         } else break;
6552                 }
6553 
6554                 /*
6555                  * In case of sched_debug() we verify the above assumption.
6556                  */
6557                 if (!sched_debug())
6558                         break;
6559         }
6560 
6561         if (!level)
6562                 return;
6563 
6564         /*
6565          * 'level' contains the number of unique distances, excluding the
6566          * identity distance node_distance(i,i).
6567          *
6568          * The sched_domains_numa_distance[] array includes the actual distance
6569          * numbers.
6570          */
6571 
6572         /*
6573          * Here, we should temporarily reset sched_domains_numa_levels to 0.
6574          * If it fails to allocate memory for array sched_domains_numa_masks[][],
6575          * the array will contain less then 'level' members. This could be
6576          * dangerous when we use it to iterate array sched_domains_numa_masks[][]
6577          * in other functions.
6578          *
6579          * We reset it to 'level' at the end of this function.
6580          */
6581         sched_domains_numa_levels = 0;
6582 
6583         sched_domains_numa_masks = kzalloc(sizeof(void *) * level, GFP_KERNEL);
6584         if (!sched_domains_numa_masks)
6585                 return;
6586 
6587         /*
6588          * Now for each level, construct a mask per node which contains all
6589          * cpus of nodes that are that many hops away from us.
6590          */
6591         for (i = 0; i < level; i++) {
6592                 sched_domains_numa_masks[i] =
6593                         kzalloc(nr_node_ids * sizeof(void *), GFP_KERNEL);
6594                 if (!sched_domains_numa_masks[i])
6595                         return;
6596 
6597                 for (j = 0; j < nr_node_ids; j++) {
6598                         struct cpumask *mask = kzalloc(cpumask_size(), GFP_KERNEL);
6599                         if (!mask)
6600                                 return;
6601 
6602                         sched_domains_numa_masks[i][j] = mask;
6603 
6604                         for_each_node(k) {
6605                                 if (node_distance(j, k) > sched_domains_numa_distance[i])
6606                                         continue;
6607 
6608                                 cpumask_or(mask, mask, cpumask_of_node(k));
6609                         }
6610                 }
6611         }
6612 
6613         /* Compute default topology size */
6614         for (i = 0; sched_domain_topology[i].mask; i++);
6615 
6616         tl = kzalloc((i + level + 1) *
6617                         sizeof(struct sched_domain_topology_level), GFP_KERNEL);
6618         if (!tl)
6619                 return;
6620 
6621         /*
6622          * Copy the default topology bits..
6623          */
6624         for (i = 0; sched_domain_topology[i].mask; i++)
6625                 tl[i] = sched_domain_topology[i];
6626 
6627         /*
6628          * .. and append 'j' levels of NUMA goodness.
6629          */
6630         for (j = 0; j < level; i++, j++) {
6631                 tl[i] = (struct sched_domain_topology_level){
6632                         .mask = sd_numa_mask,
6633                         .sd_flags = cpu_numa_flags,
6634                         .flags = SDTL_OVERLAP,
6635                         .numa_level = j,
6636                         SD_INIT_NAME(NUMA)
6637                 };
6638         }
6639 
6640         sched_domain_topology = tl;
6641 
6642         sched_domains_numa_levels = level;
6643         sched_max_numa_distance = sched_domains_numa_distance[level - 1];
6644 
6645         init_numa_topology_type();
6646 }
6647 
6648 static void sched_domains_numa_masks_set(int cpu)
6649 {
6650         int i, j;
6651         int node = cpu_to_node(cpu);
6652 
6653         for (i = 0; i < sched_domains_numa_levels; i++) {
6654                 for (j = 0; j < nr_node_ids; j++) {
6655                         if (node_distance(j, node) <= sched_domains_numa_distance[i])
6656                                 cpumask_set_cpu(cpu, sched_domains_numa_masks[i][j]);
6657                 }
6658         }
6659 }
6660 
6661 static void sched_domains_numa_masks_clear(int cpu)
6662 {
6663         int i, j;
6664         for (i = 0; i < sched_domains_numa_levels; i++) {
6665                 for (j = 0; j < nr_node_ids; j++)
6666                         cpumask_clear_cpu(cpu, sched_domains_numa_masks[i][j]);
6667         }
6668 }
6669 
6670 /*
6671  * Update sched_domains_numa_masks[level][node] array when new cpus
6672  * are onlined.
6673  */
6674 static int sched_domains_numa_masks_update(struct notifier_block *nfb,
6675                                            unsigned long action,
6676                                            void *hcpu)
6677 {
6678         int cpu = (long)hcpu;
6679 
6680         switch (action & ~CPU_TASKS_FROZEN) {
6681         case CPU_ONLINE:
6682                 sched_domains_numa_masks_set(cpu);
6683                 break;
6684 
6685         case CPU_DEAD:
6686                 sched_domains_numa_masks_clear(cpu);
6687                 break;
6688 
6689         default:
6690                 return NOTIFY_DONE;
6691         }
6692 
6693         return NOTIFY_OK;
6694 }
6695 #else
6696 static inline void sched_init_numa(void)
6697 {
6698 }
6699 
6700 static int sched_domains_numa_masks_update(struct notifier_block *nfb,
6701                                            unsigned long action,
6702                                            void *hcpu)
6703 {
6704         return 0;
6705 }
6706 #endif /* CONFIG_NUMA */
6707 
6708 static int __sdt_alloc(const struct cpumask *cpu_map)
6709 {
6710         struct sched_domain_topology_level *tl;
6711         int j;
6712 
6713         for_each_sd_topology(tl) {
6714                 struct sd_data *sdd = &tl->data;
6715 
6716                 sdd->sd = alloc_percpu(struct sched_domain *);
6717                 if (!sdd->sd)
6718                         return -ENOMEM;
6719 
6720                 sdd->sg = alloc_percpu(struct sched_group *);
6721                 if (!sdd->sg)
6722                         return -ENOMEM;
6723 
6724                 sdd->sgc = alloc_percpu(struct sched_group_capacity *);
6725                 if (!sdd->sgc)
6726                         return -ENOMEM;
6727 
6728                 for_each_cpu(j, cpu_map) {
6729                         struct sched_domain *sd;
6730                         struct sched_group *sg;
6731                         struct sched_group_capacity *sgc;
6732 
6733                         sd = kzalloc_node(sizeof(struct sched_domain) + cpumask_size(),
6734                                         GFP_KERNEL, cpu_to_node(j));
6735                         if (!sd)
6736                                 return -ENOMEM;
6737 
6738                         *per_cpu_ptr(sdd->sd, j) = sd;
6739 
6740                         sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
6741                                         GFP_KERNEL, cpu_to_node(j));
6742                         if (!sg)
6743                                 return -ENOMEM;
6744 
6745                         sg->next = sg;
6746 
6747                         *per_cpu_ptr(sdd->sg, j) = sg;
6748 
6749                         sgc = kzalloc_node(sizeof(struct sched_group_capacity) + cpumask_size(),
6750                                         GFP_KERNEL, cpu_to_node(j));
6751                         if (!sgc)
6752                                 return -ENOMEM;
6753 
6754                         *per_cpu_ptr(sdd->sgc, j) = sgc;
6755                 }
6756         }
6757 
6758         return 0;
6759 }
6760 
6761 static void __sdt_free(const struct cpumask *cpu_map)
6762 {
6763         struct sched_domain_topology_level *tl;
6764         int j;
6765 
6766         for_each_sd_topology(tl) {
6767                 struct sd_data *sdd = &tl->data;
6768 
6769                 for_each_cpu(j, cpu_map) {
6770                         struct sched_domain *sd;
6771 
6772                         if (sdd->sd) {
6773                                 sd = *per_cpu_ptr(sdd->sd, j);
6774                                 if (sd && (sd->flags & SD_OVERLAP))
6775                                         free_sched_groups(sd->groups, 0);
6776                                 kfree(*per_cpu_ptr(sdd->sd, j));
6777                         }
6778 
6779                         if (sdd->sg)
6780                                 kfree(*per_cpu_ptr(sdd->sg, j));
6781                         if (sdd->sgc)
6782                                 kfree(*per_cpu_ptr(sdd->sgc, j));
6783                 }
6784                 free_percpu(sdd->sd);
6785                 sdd->sd = NULL;
6786                 free_percpu(sdd->sg);
6787                 sdd->sg = NULL;
6788                 free_percpu(sdd->sgc);
6789                 sdd->sgc = NULL;
6790         }
6791 }
6792 
6793 struct sched_domain *build_sched_domain(struct sched_domain_topology_level *tl,
6794                 const struct cpumask *cpu_map, struct sched_domain_attr *attr,
6795                 struct sched_domain *child, int cpu)
6796 {
6797         struct sched_domain *sd = sd_init(tl, cpu);
6798         if (!sd)
6799                 return child;
6800 
6801         cpumask_and(sched_domain_span(sd), cpu_map, tl->mask(cpu));
6802         if (child) {
6803                 sd->level = child->level + 1;
6804                 sched_domain_level_max = max(sched_domain_level_max, sd->level);
6805                 child->parent = sd;
6806                 sd->child = child;
6807 
6808                 if (!cpumask_subset(sched_domain_span(child),
6809                                     sched_domain_span(sd))) {
6810                         pr_err("BUG: arch topology borken\n");
6811 #ifdef CONFIG_SCHED_DEBUG
6812                         pr_err("     the %s domain not a subset of the %s domain\n",
6813                                         child->name, sd->name);
6814 #endif
6815                         /* Fixup, ensure @sd has at least @child cpus. */
6816                         cpumask_or(sched_domain_span(sd),
6817                                    sched_domain_span(sd),
6818                                    sched_domain_span(child));
6819                 }
6820 
6821         }
6822         set_domain_attribute(sd, attr);
6823 
6824         return sd;
6825 }
6826 
6827 /*
6828  * Build sched domains for a given set of cpus and attach the sched domains
6829  * to the individual cpus
6830  */
6831 static int build_sched_domains(const struct cpumask *cpu_map,
6832                                struct sched_domain_attr *attr)
6833 {
6834         enum s_alloc alloc_state;
6835         struct sched_domain *sd;
6836         struct s_data d;
6837         int i, ret = -ENOMEM;
6838 
6839         alloc_state = __visit_domain_allocation_hell(&d, cpu_map);
6840         if (alloc_state != sa_rootdomain)
6841                 goto error;
6842 
6843         /* Set up domains for cpus specified by the cpu_map. */
6844         for_each_cpu(i, cpu_map) {
6845                 struct sched_domain_topology_level *tl;
6846 
6847                 sd = NULL;
6848                 for_each_sd_topology(tl) {
6849                         sd = build_sched_domain(tl, cpu_map, attr, sd, i);
6850                         if (tl == sched_domain_topology)
6851                                 *per_cpu_ptr(d.sd, i) = sd;
6852                         if (tl->flags & SDTL_OVERLAP || sched_feat(FORCE_SD_OVERLAP))
6853                                 sd->flags |= SD_OVERLAP;
6854                         if (cpumask_equal(cpu_map, sched_domain_span(sd)))
6855                                 break;
6856                 }
6857         }
6858 
6859         /* Build the groups for the domains */
6860         for_each_cpu(i, cpu_map) {
6861                 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
6862                         sd->span_weight = cpumask_weight(sched_domain_span(sd));
6863                         if (sd->flags & SD_OVERLAP) {
6864                                 if (build_overlap_sched_groups(sd, i))
6865                                         goto error;
6866                         } else {
6867                                 if (build_sched_groups(sd, i))
6868                                         goto error;
6869                         }
6870                 }
6871         }
6872 
6873         /* Calculate CPU capacity for physical packages and nodes */
6874         for (i = nr_cpumask_bits-1; i >= 0; i--) {
6875                 if (!cpumask_test_cpu(i, cpu_map))
6876                         continue;
6877 
6878                 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
6879                         claim_allocations(i, sd);
6880                         init_sched_groups_capacity(i, sd);
6881                 }
6882         }
6883 
6884         /* Attach the domains */
6885         rcu_read_lock();
6886         for_each_cpu(i, cpu_map) {
6887                 sd = *per_cpu_ptr(d.sd, i);
6888                 cpu_attach_domain(sd, d.rd, i);
6889         }
6890         rcu_read_unlock();
6891 
6892         ret = 0;
6893 error:
6894         __free_domain_allocs(&d, alloc_state, cpu_map);
6895         return ret;
6896 }
6897 
6898 static cpumask_var_t *doms_cur; /* current sched domains */
6899 static int ndoms_cur;           /* number of sched domains in 'doms_cur' */
6900 static struct sched_domain_attr *dattr_cur;
6901                                 /* attribues of custom domains in 'doms_cur' */
6902 
6903 /*
6904  * Special case: If a kmalloc of a doms_cur partition (array of
6905  * cpumask) fails, then fallback to a single sched domain,
6906  * as determined by the single cpumask fallback_doms.
6907  */
6908 static cpumask_var_t fallback_doms;
6909 
6910 /*
6911  * arch_update_cpu_topology lets virtualized architectures update the
6912  * cpu core maps. It is supposed to return 1 if the topology changed
6913  * or 0 if it stayed the same.
6914  */
6915 int __weak arch_update_cpu_topology(void)
6916 {
6917         return 0;
6918 }
6919 
6920 cpumask_var_t *alloc_sched_domains(unsigned int ndoms)
6921 {
6922         int i;
6923         cpumask_var_t *doms;
6924 
6925         doms = kmalloc(sizeof(*doms) * ndoms, GFP_KERNEL);
6926         if (!doms)
6927                 return NULL;
6928         for (i = 0; i < ndoms; i++) {
6929                 if (!alloc_cpumask_var(&doms[i], GFP_KERNEL)) {
6930                         free_sched_domains(doms, i);
6931                         return NULL;
6932                 }
6933         }
6934         return doms;
6935 }
6936 
6937 void free_sched_domains(cpumask_var_t doms[], unsigned int ndoms)
6938 {
6939         unsigned int i;
6940         for (i = 0; i < ndoms; i++)
6941                 free_cpumask_var(doms[i]);
6942         kfree(doms);
6943 }
6944 
6945 /*
6946  * Set up scheduler domains and groups. Callers must hold the hotplug lock.
6947  * For now this just excludes isolated cpus, but could be used to
6948  * exclude other special cases in the future.
6949  */
6950 static int init_sched_domains(const struct cpumask *cpu_map)
6951 {
6952         int err;
6953 
6954         arch_update_cpu_topology();
6955         ndoms_cur = 1;
6956         doms_cur = alloc_sched_domains(ndoms_cur);
6957         if (!doms_cur)
6958                 doms_cur = &fallback_doms;
6959         cpumask_andnot(doms_cur[0], cpu_map, cpu_isolated_map);
6960         err = build_sched_domains(doms_cur[0], NULL);
6961         register_sched_domain_sysctl();
6962 
6963         return err;
6964 }
6965 
6966 /*
6967  * Detach sched domains from a group of cpus specified in cpu_map
6968  * These cpus will now be attached to the NULL domain
6969  */
6970 static void detach_destroy_domains(const struct cpumask *cpu_map)
6971 {
6972         int i;
6973 
6974         rcu_read_lock();
6975         for_each_cpu(i, cpu_map)
6976                 cpu_attach_domain(NULL, &def_root_domain, i);
6977         rcu_read_unlock();
6978 }
6979 
6980 /* handle null as "default" */
6981 static int dattrs_equal(struct sched_domain_attr *cur, int idx_cur,
6982                         struct sched_domain_attr *new, int idx_new)
6983 {
6984         struct sched_domain_attr tmp;
6985 
6986         /* fast path */
6987         if (!new && !cur)
6988                 return 1;
6989 
6990         tmp = SD_ATTR_INIT;
6991         return !memcmp(cur ? (cur + idx_cur) : &tmp,
6992                         new ? (new + idx_new) : &tmp,
6993                         sizeof(struct sched_domain_attr));
6994 }
6995 
6996 /*
6997  * Partition sched domains as specified by the 'ndoms_new'
6998  * cpumasks in the array doms_new[] of cpumasks. This compares
6999  * doms_new[] to the current sched domain partitioning, doms_cur[].
7000  * It destroys each deleted domain and builds each new domain.
7001  *
7002  * 'doms_new' is an array of cpumask_var_t's of length 'ndoms_new'.
7003  * The masks don't intersect (don't overlap.) We should setup one
7004  * sched domain for each mask. CPUs not in any of the cpumasks will
7005  * not be load balanced. If the same cpumask appears both in the
7006  * current 'doms_cur' domains and in the new 'doms_new', we can leave
7007  * it as it is.
7008  *
7009  * The passed in 'doms_new' should be allocated using
7010  * alloc_sched_domains.  This routine takes ownership of it and will
7011  * free_sched_domains it when done with it. If the caller failed the
7012  * alloc call, then it can pass in doms_new == NULL && ndoms_new == 1,
7013  * and partition_sched_domains() will fallback to the single partition
7014  * 'fallback_doms', it also forces the domains to be rebuilt.
7015  *
7016  * If doms_new == NULL it will be replaced with cpu_online_mask.
7017  * ndoms_new == 0 is a special case for destroying existing domains,
7018  * and it will not create the default domain.
7019  *
7020  * Call with hotplug lock held
7021  */
7022 void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
7023                              struct sched_domain_attr *dattr_new)
7024 {
7025         int i, j, n;
7026         int new_topology;
7027 
7028         mutex_lock(&sched_domains_mutex);
7029 
7030         /* always unregister in case we don't destroy any domains */
7031         unregister_sched_domain_sysctl();
7032 
7033         /* Let architecture update cpu core mappings. */
7034         new_topology = arch_update_cpu_topology();
7035 
7036         n = doms_new ? ndoms_new : 0;
7037 
7038         /* Destroy deleted domains */
7039         for (i = 0; i < ndoms_cur; i++) {
7040                 for (j = 0; j < n && !new_topology; j++) {
7041                         if (cpumask_equal(doms_cur[i], doms_new[j])
7042                             && dattrs_equal(dattr_cur, i, dattr_new, j))
7043                                 goto match1;
7044                 }
7045                 /* no match - a current sched domain not in new doms_new[] */
7046                 detach_destroy_domains(doms_cur[i]);
7047 match1:
7048                 ;
7049         }
7050 
7051         n = ndoms_cur;
7052         if (doms_new == NULL) {
7053                 n = 0;
7054                 doms_new = &fallback_doms;
7055                 cpumask_andnot(doms_new[0], cpu_active_mask, cpu_isolated_map);
7056                 WARN_ON_ONCE(dattr_new);
7057         }
7058 
7059         /* Build new domains */
7060         for (i = 0; i < ndoms_new; i++) {
7061                 for (j = 0; j < n && !new_topology; j++) {
7062                         if (cpumask_equal(doms_new[i], doms_cur[j])
7063                             && dattrs_equal(dattr_new, i, dattr_cur, j))
7064                                 goto match2;
7065                 }
7066                 /* no match - add a new doms_new */
7067                 build_sched_domains(doms_new[i], dattr_new ? dattr_new + i : NULL);
7068 match2:
7069                 ;
7070         }
7071 
7072         /* Remember the new sched domains */
7073         if (doms_cur != &fallback_doms)
7074                 free_sched_domains(doms_cur, ndoms_cur);
7075         kfree(dattr_cur);       /* kfree(NULL) is safe */
7076         doms_cur = doms_new;
7077         dattr_cur = dattr_new;
7078         ndoms_cur = ndoms_new;
7079 
7080         register_sched_domain_sysctl();
7081 
7082         mutex_unlock(&sched_domains_mutex);
7083 }
7084 
7085 static int num_cpus_frozen;     /* used to mark begin/end of suspend/resume */
7086 
7087 /*
7088  * Update cpusets according to cpu_active mask.  If cpusets are
7089  * disabled, cpuset_update_active_cpus() becomes a simple wrapper
7090  * around partition_sched_domains().
7091  *
7092  * If we come here as part of a suspend/resume, don't touch cpusets because we
7093  * want to restore it back to its original state upon resume anyway.
7094  */
7095 static int cpuset_cpu_active(struct notifier_block *nfb, unsigned long action,
7096                              void *hcpu)
7097 {
7098         switch (action) {
7099         case CPU_ONLINE_FROZEN:
7100         case CPU_DOWN_FAILED_FROZEN:
7101 
7102                 /*
7103                  * num_cpus_frozen tracks how many CPUs are involved in suspend
7104                  * resume sequence. As long as this is not the last online
7105                  * operation in the resume sequence, just build a single sched
7106                  * domain, ignoring cpusets.
7107                  */
7108                 num_cpus_frozen--;
7109                 if (likely(num_cpus_frozen)) {
7110                         partition_sched_domains(1, NULL, NULL);
7111                         break;
7112                 }
7113 
7114                 /*
7115                  * This is the last CPU online operation. So fall through and
7116                  * restore the original sched domains by considering the
7117                  * cpuset configurations.
7118                  */
7119 
7120         case CPU_ONLINE:
7121                 cpuset_update_active_cpus(true);
7122                 break;
7123         default:
7124                 return NOTIFY_DONE;
7125         }
7126         return NOTIFY_OK;
7127 }
7128 
7129 static int cpuset_cpu_inactive(struct notifier_block *nfb, unsigned long action,
7130                                void *hcpu)
7131 {
7132         unsigned long flags;
7133         long cpu = (long)hcpu;
7134         struct dl_bw *dl_b;
7135         bool overflow;
7136         int cpus;
7137 
7138         switch (action) {
7139         case CPU_DOWN_PREPARE:
7140                 rcu_read_lock_sched();
7141                 dl_b = dl_bw_of(cpu);
7142 
7143                 raw_spin_lock_irqsave(&dl_b->lock, flags);
7144                 cpus = dl_bw_cpus(cpu);
7145                 overflow = __dl_overflow(dl_b, cpus, 0, 0);
7146                 raw_spin_unlock_irqrestore(&dl_b->lock, flags);
7147 
7148                 rcu_read_unlock_sched();
7149 
7150                 if (overflow)
7151                         return notifier_from_errno(-EBUSY);
7152                 cpuset_update_active_cpus(false);
7153                 break;
7154         case CPU_DOWN_PREPARE_FROZEN:
7155                 num_cpus_frozen++;
7156                 partition_sched_domains(1, NULL, NULL);
7157                 break;
7158         default:
7159                 return NOTIFY_DONE;
7160         }
7161         return NOTIFY_OK;
7162 }
7163 
7164 void __init sched_init_smp(void)
7165 {
7166         cpumask_var_t non_isolated_cpus;
7167 
7168         alloc_cpumask_var(&non_isolated_cpus, GFP_KERNEL);
7169         alloc_cpumask_var(&fallback_doms, GFP_KERNEL);
7170 
7171         sched_init_numa();
7172 
7173         /*
7174          * There's no userspace yet to cause hotplug operations; hence all the
7175          * cpu masks are stable and all blatant races in the below code cannot
7176          * happen.
7177          */
7178         mutex_lock(&sched_domains_mutex);
7179         init_sched_domains(cpu_active_mask);
7180         cpumask_andnot(non_isolated_cpus, cpu_possible_mask, cpu_isolated_map);
7181         if (cpumask_empty(non_isolated_cpus))
7182                 cpumask_set_cpu(smp_processor_id(), non_isolated_cpus);
7183         mutex_unlock(&sched_domains_mutex);
7184 
7185         hotcpu_notifier(sched_domains_numa_masks_update, CPU_PRI_SCHED_ACTIVE);
7186         hotcpu_notifier(cpuset_cpu_active, CPU_PRI_CPUSET_ACTIVE);
7187         hotcpu_notifier(cpuset_cpu_inactive, CPU_PRI_CPUSET_INACTIVE);
7188 
7189         init_hrtick();
7190 
7191         /* Move init over to a non-isolated CPU */
7192         if (set_cpus_allowed_ptr(current, non_isolated_cpus) < 0)
7193                 BUG();
7194         sched_init_granularity();
7195         free_cpumask_var(non_isolated_cpus);
7196 
7197         init_sched_rt_class();
7198         init_sched_dl_class();
7199 }
7200 #else
7201 void __init sched_init_smp(void)
7202 {
7203         sched_init_granularity();
7204 }
7205 #endif /* CONFIG_SMP */
7206 
7207 int in_sched_functions(unsigned long addr)
7208 {
7209         return in_lock_functions(addr) ||
7210                 (addr >= (unsigned long)__sched_text_start
7211                 && addr < (unsigned long)__sched_text_end);
7212 }
7213 
7214 #ifdef CONFIG_CGROUP_SCHED
7215 /*
7216  * Default task group.
7217  * Every task in system belongs to this group at bootup.
7218  */
7219 struct task_group root_task_group;
7220 LIST_HEAD(task_groups);
7221 
7222 /* Cacheline aligned slab cache for task_group */
7223 static struct kmem_cache *task_group_cache __read_mostly;
7224 #endif
7225 
7226 DECLARE_PER_CPU(cpumask_var_t, load_balance_mask);
7227 
7228 void __init sched_init(void)
7229 {
7230         int i, j;
7231         unsigned long alloc_size = 0, ptr;
7232 
7233 #ifdef CONFIG_FAIR_GROUP_SCHED
7234         alloc_size += 2 * nr_cpu_ids * sizeof(void **);
7235 #endif
7236 #ifdef CONFIG_RT_GROUP_SCHED
7237         alloc_size += 2 * nr_cpu_ids * sizeof(void **);
7238 #endif
7239         if (alloc_size) {
7240                 ptr = (unsigned long)kzalloc(alloc_size, GFP_NOWAIT);
7241 
7242 #ifdef CONFIG_FAIR_GROUP_SCHED
7243                 root_task_group.se = (struct sched_entity **)ptr;
7244                 ptr += nr_cpu_ids * sizeof(void **);
7245 
7246                 root_task_group.cfs_rq = (struct cfs_rq **)ptr;
7247                 ptr += nr_cpu_ids * sizeof(void **);
7248 
7249 #endif /* CONFIG_FAIR_GROUP_SCHED */
7250 #ifdef CONFIG_RT_GROUP_SCHED
7251                 root_task_group.rt_se = (struct sched_rt_entity **)ptr;
7252                 ptr += nr_cpu_ids * sizeof(void **);
7253 
7254                 root_task_group.rt_rq = (struct rt_rq **)ptr;
7255                 ptr += nr_cpu_ids * sizeof(void **);
7256 
7257 #endif /* CONFIG_RT_GROUP_SCHED */
7258         }
7259 #ifdef CONFIG_CPUMASK_OFFSTACK
7260         for_each_possible_cpu(i) {
7261                 per_cpu(load_balance_mask, i) = (cpumask_var_t)kzalloc_node(
7262                         cpumask_size(), GFP_KERNEL, cpu_to_node(i));
7263         }
7264 #endif /* CONFIG_CPUMASK_OFFSTACK */
7265 
7266         init_rt_bandwidth(&def_rt_bandwidth,
7267                         global_rt_period(), global_rt_runtime());
7268         init_dl_bandwidth(&def_dl_bandwidth,
7269                         global_rt_period(), global_rt_runtime());
7270 
7271 #ifdef CONFIG_SMP
7272         init_defrootdomain();
7273 #endif
7274 
7275 #ifdef CONFIG_RT_GROUP_SCHED
7276         init_rt_bandwidth(&root_task_group.rt_bandwidth,
7277                         global_rt_period(), global_rt_runtime());
7278 #endif /* CONFIG_RT_GROUP_SCHED */
7279 
7280 #ifdef CONFIG_CGROUP_SCHED
7281         task_group_cache = KMEM_CACHE(task_group, 0);
7282 
7283         list_add(&root_task_group.list, &task_groups);
7284         INIT_LIST_HEAD(&root_task_group.children);
7285         INIT_LIST_HEAD(&root_task_group.siblings);
7286         autogroup_init(&init_task);
7287 #endif /* CONFIG_CGROUP_SCHED */
7288 
7289         for_each_possible_cpu(i) {
7290                 struct rq *rq;
7291 
7292                 rq = cpu_rq(i);
7293                 raw_spin_lock_init(&rq->lock);
7294                 rq->nr_running = 0;
7295                 rq->calc_load_active = 0;
7296                 rq->calc_load_update = jiffies + LOAD_FREQ;
7297                 init_cfs_rq(&rq->cfs);
7298                 init_rt_rq(&rq->rt);
7299                 init_dl_rq(&rq->dl);
7300 #ifdef CONFIG_FAIR_GROUP_SCHED
7301                 root_task_group.shares = ROOT_TASK_GROUP_LOAD;
7302                 INIT_LIST_HEAD(&rq->leaf_cfs_rq_list);
7303                 /*
7304                  * How much cpu bandwidth does root_task_group get?
7305                  *
7306                  * In case of task-groups formed thr' the cgroup filesystem, it
7307                  * gets 100% of the cpu resources in the system. This overall
7308                  * system cpu resource is divided among the tasks of
7309                  * root_task_group and its child task-groups in a fair manner,
7310                  * based on each entity's (task or task-group's) weight
7311                  * (se->load.weight).
7312                  *
7313                  * In other words, if root_task_group has 10 tasks of weight
7314                  * 1024) and two child groups A0 and A1 (of weight 1024 each),
7315                  * then A0's share of the cpu resource is:
7316                  *
7317                  *      A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33%
7318                  *
7319                  * We achieve this by letting root_task_group's tasks sit
7320                  * directly in rq->cfs (i.e root_task_group->se[] = NULL).
7321                  */
7322                 init_cfs_bandwidth(&root_task_group.cfs_bandwidth);
7323                 init_tg_cfs_entry(&root_task_group, &rq->cfs, NULL, i, NULL);
7324 #endif /* CONFIG_FAIR_GROUP_SCHED */
7325 
7326                 rq->rt.rt_runtime = def_rt_bandwidth.rt_runtime;
7327 #ifdef CONFIG_RT_GROUP_SCHED
7328                 init_tg_rt_entry(&root_task_group, &rq->rt, NULL, i, NULL);
7329 #endif
7330 
7331                 for (j = 0; j < CPU_LOAD_IDX_MAX; j++)
7332                         rq->cpu_load[j] = 0;
7333 
7334                 rq->last_load_update_tick = jiffies;
7335 
7336 #ifdef CONFIG_SMP
7337                 rq->sd = NULL;
7338                 rq->rd = NULL;
7339                 rq->cpu_capacity = rq->cpu_capacity_orig = SCHED_CAPACITY_SCALE;
7340                 rq->balance_callback = NULL;
7341                 rq->active_balance = 0;
7342                 rq->next_balance = jiffies;
7343                 rq->push_cpu = 0;
7344                 rq->cpu = i;
7345                 rq->online = 0;
7346                 rq->idle_stamp = 0;
7347                 rq->avg_idle = 2*sysctl_sched_migration_cost;
7348                 rq->max_idle_balance_cost = sysctl_sched_migration_cost;
7349 
7350                 INIT_LIST_HEAD(&rq->cfs_tasks);
7351 
7352                 rq_attach_root(rq, &def_root_domain);
7353 #ifdef CONFIG_NO_HZ_COMMON
7354                 rq->nohz_flags = 0;
7355 #endif
7356 #ifdef CONFIG_NO_HZ_FULL
7357                 rq->last_sched_tick = 0;
7358 #endif
7359 #endif
7360                 init_rq_hrtick(rq);
7361                 atomic_set(&rq->nr_iowait, 0);
7362         }
7363 
7364         set_load_weight(&init_task);
7365 
7366 #ifdef CONFIG_PREEMPT_NOTIFIERS
7367         INIT_HLIST_HEAD(&init_task.preempt_notifiers);
7368 #endif
7369 
7370         /*
7371          * The boot idle thread does lazy MMU switching as well:
7372          */
7373         atomic_inc(&init_mm.mm_count);
7374         enter_lazy_tlb(&init_mm, current);
7375 
7376         /*
7377          * During early bootup we pretend to be a normal task:
7378          */
7379         current->sched_class = &fair_sched_class;
7380 
7381         /*
7382          * Make us the idle thread. Technically, schedule() should not be
7383          * called from this thread, however somewhere below it might be,
7384          * but because we are the idle thread, we just pick up running again
7385          * when this runqueue becomes "idle".
7386          */
7387         init_idle(current, smp_processor_id());
7388 
7389         calc_load_update = jiffies + LOAD_FREQ;
7390 
7391 #ifdef CONFIG_SMP
7392         zalloc_cpumask_var(&sched_domains_tmpmask, GFP_NOWAIT);
7393         /* May be allocated at isolcpus cmdline parse time */
7394         if (cpu_isolated_map == NULL)
7395                 zalloc_cpumask_var(&cpu_isolated_map, GFP_NOWAIT);
7396         idle_thread_set_boot_cpu();
7397         set_cpu_rq_start_time();
7398 #endif
7399         init_sched_fair_class();
7400 
7401         scheduler_running = 1;
7402 }
7403 
7404 #ifdef CONFIG_DEBUG_ATOMIC_SLEEP
7405 static inline int preempt_count_equals(int preempt_offset)
7406 {
7407         int nested = preempt_count() + rcu_preempt_depth();
7408 
7409         return (nested == preempt_offset);
7410 }
7411 
7412 void __might_sleep(const char *file, int line, int preempt_offset)
7413 {
7414         /*
7415          * Blocking primitives will set (and therefore destroy) current->state,
7416          * since we will exit with TASK_RUNNING make sure we enter with it,
7417          * otherwise we will destroy state.
7418          */
7419         WARN_ONCE(current->state != TASK_RUNNING && current->task_state_change,
7420                         "do not call blocking ops when !TASK_RUNNING; "
7421                         "state=%lx set at [<%p>] %pS\n",
7422                         current->state,
7423                         (void *)current->task_state_change,
7424                         (void *)current->task_state_change);
7425 
7426         ___might_sleep(file, line, preempt_offset);
7427 }
7428 EXPORT_SYMBOL(__might_sleep);
7429 
7430 void ___might_sleep(const char *file, int line, int preempt_offset)
7431 {
7432         static unsigned long prev_jiffy;        /* ratelimiting */
7433 
7434         rcu_sleep_check(); /* WARN_ON_ONCE() by default, no rate limit reqd. */
7435         if ((preempt_count_equals(preempt_offset) && !irqs_disabled() &&
7436              !is_idle_task(current)) ||
7437             system_state != SYSTEM_RUNNING || oops_in_progress)
7438                 return;
7439         if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
7440                 return;
7441         prev_jiffy = jiffies;
7442 
7443         printk(KERN_ERR
7444                 "BUG: sleeping function called from invalid context at %s:%d\n",
7445                         file, line);
7446         printk(KERN_ERR
7447                 "in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n",
7448                         in_atomic(), irqs_disabled(),
7449                         current->pid, current->comm);
7450 
7451         if (task_stack_end_corrupted(current))
7452                 printk(KERN_EMERG "Thread overran stack, or stack corrupted\n");
7453 
7454         debug_show_held_locks(current);
7455         if (irqs_disabled())
7456                 print_irqtrace_events(current);
7457 #ifdef CONFIG_DEBUG_PREEMPT
7458         if (!preempt_count_equals(preempt_offset)) {
7459                 pr_err("Preemption disabled at:");
7460                 print_ip_sym(current->preempt_disable_ip);
7461                 pr_cont("\n");
7462         }
7463 #endif
7464         dump_stack();
7465 }
7466 EXPORT_SYMBOL(___might_sleep);
7467 #endif
7468 
7469 #ifdef CONFIG_MAGIC_SYSRQ
7470 void normalize_rt_tasks(void)
7471 {
7472         struct task_struct *g, *p;
7473         struct sched_attr attr = {
7474                 .sched_policy = SCHED_NORMAL,
7475         };
7476 
7477         read_lock(&tasklist_lock);
7478         for_each_process_thread(g, p) {
7479                 /*
7480                  * Only normalize user tasks:
7481                  */
7482                 if (p->flags & PF_KTHREAD)
7483                         continue;
7484 
7485                 p->se.exec_start                = 0;
7486 #ifdef CONFIG_SCHEDSTATS
7487                 p->se.statistics.wait_start     = 0;
7488                 p->se.statistics.sleep_start    = 0;
7489                 p->se.statistics.block_start    = 0;
7490 #endif
7491 
7492                 if (!dl_task(p) && !rt_task(p)) {
7493                         /*
7494                          * Renice negative nice level userspace
7495                          * tasks back to 0:
7496                          */
7497                         if (task_nice(p) < 0)