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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/mm.h>
 30 #include <linux/module.h>
 31 #include <linux/nmi.h>
 32 #include <linux/init.h>
 33 #include <linux/uaccess.h>
 34 #include <linux/highmem.h>
 35 #include <asm/mmu_context.h>
 36 #include <linux/interrupt.h>
 37 #include <linux/capability.h>
 38 #include <linux/completion.h>
 39 #include <linux/kernel_stat.h>
 40 #include <linux/debug_locks.h>
 41 #include <linux/perf_event.h>
 42 #include <linux/security.h>
 43 #include <linux/notifier.h>
 44 #include <linux/profile.h>
 45 #include <linux/freezer.h>
 46 #include <linux/vmalloc.h>
 47 #include <linux/blkdev.h>
 48 #include <linux/delay.h>
 49 #include <linux/pid_namespace.h>
 50 #include <linux/smp.h>
 51 #include <linux/threads.h>
 52 #include <linux/timer.h>
 53 #include <linux/rcupdate.h>
 54 #include <linux/cpu.h>
 55 #include <linux/cpuset.h>
 56 #include <linux/percpu.h>
 57 #include <linux/proc_fs.h>
 58 #include <linux/seq_file.h>
 59 #include <linux/sysctl.h>
 60 #include <linux/syscalls.h>
 61 #include <linux/times.h>
 62 #include <linux/tsacct_kern.h>
 63 #include <linux/kprobes.h>
 64 #include <linux/delayacct.h>
 65 #include <linux/unistd.h>
 66 #include <linux/pagemap.h>
 67 #include <linux/hrtimer.h>
 68 #include <linux/tick.h>
 69 #include <linux/debugfs.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/binfmts.h>
 75 #include <linux/context_tracking.h>
 76 
 77 #include <asm/switch_to.h>
 78 #include <asm/tlb.h>
 79 #include <asm/irq_regs.h>
 80 #include <asm/mutex.h>
 81 #ifdef CONFIG_PARAVIRT
 82 #include <asm/paravirt.h>
 83 #endif
 84 
 85 #include "sched.h"
 86 #include "../workqueue_internal.h"
 87 #include "../smpboot.h"
 88 
 89 #define CREATE_TRACE_POINTS
 90 #include <trace/events/sched.h>
 91 
 92 void start_bandwidth_timer(struct hrtimer *period_timer, ktime_t period)
 93 {
 94         unsigned long delta;
 95         ktime_t soft, hard, now;
 96 
 97         for (;;) {
 98                 if (hrtimer_active(period_timer))
 99                         break;
100 
101                 now = hrtimer_cb_get_time(period_timer);
102                 hrtimer_forward(period_timer, now, period);
103 
104                 soft = hrtimer_get_softexpires(period_timer);
105                 hard = hrtimer_get_expires(period_timer);
106                 delta = ktime_to_ns(ktime_sub(hard, soft));
107                 __hrtimer_start_range_ns(period_timer, soft, delta,
108                                          HRTIMER_MODE_ABS_PINNED, 0);
109         }
110 }
111 
112 DEFINE_MUTEX(sched_domains_mutex);
113 DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
114 
115 static void update_rq_clock_task(struct rq *rq, s64 delta);
116 
117 void update_rq_clock(struct rq *rq)
118 {
119         s64 delta;
120 
121         if (rq->skip_clock_update > 0)
122                 return;
123 
124         delta = sched_clock_cpu(cpu_of(rq)) - rq->clock;
125         rq->clock += delta;
126         update_rq_clock_task(rq, delta);
127 }
128 
129 /*
130  * Debugging: various feature bits
131  */
132 
133 #define SCHED_FEAT(name, enabled)       \
134         (1UL << __SCHED_FEAT_##name) * enabled |
135 
136 const_debug unsigned int sysctl_sched_features =
137 #include "features.h"
138         0;
139 
140 #undef SCHED_FEAT
141 
142 #ifdef CONFIG_SCHED_DEBUG
143 #define SCHED_FEAT(name, enabled)       \
144         #name ,
145 
146 static const char * const sched_feat_names[] = {
147 #include "features.h"
148 };
149 
150 #undef SCHED_FEAT
151 
152 static int sched_feat_show(struct seq_file *m, void *v)
153 {
154         int i;
155 
156         for (i = 0; i < __SCHED_FEAT_NR; i++) {
157                 if (!(sysctl_sched_features & (1UL << i)))
158                         seq_puts(m, "NO_");
159                 seq_printf(m, "%s ", sched_feat_names[i]);
160         }
161         seq_puts(m, "\n");
162 
163         return 0;
164 }
165 
166 #ifdef HAVE_JUMP_LABEL
167 
168 #define jump_label_key__true  STATIC_KEY_INIT_TRUE
169 #define jump_label_key__false STATIC_KEY_INIT_FALSE
170 
171 #define SCHED_FEAT(name, enabled)       \
172         jump_label_key__##enabled ,
173 
174 struct static_key sched_feat_keys[__SCHED_FEAT_NR] = {
175 #include "features.h"
176 };
177 
178 #undef SCHED_FEAT
179 
180 static void sched_feat_disable(int i)
181 {
182         if (static_key_enabled(&sched_feat_keys[i]))
183                 static_key_slow_dec(&sched_feat_keys[i]);
184 }
185 
186 static void sched_feat_enable(int i)
187 {
188         if (!static_key_enabled(&sched_feat_keys[i]))
189                 static_key_slow_inc(&sched_feat_keys[i]);
190 }
191 #else
192 static void sched_feat_disable(int i) { };
193 static void sched_feat_enable(int i) { };
194 #endif /* HAVE_JUMP_LABEL */
195 
196 static int sched_feat_set(char *cmp)
197 {
198         int i;
199         int neg = 0;
200 
201         if (strncmp(cmp, "NO_", 3) == 0) {
202                 neg = 1;
203                 cmp += 3;
204         }
205 
206         for (i = 0; i < __SCHED_FEAT_NR; i++) {
207                 if (strcmp(cmp, sched_feat_names[i]) == 0) {
208                         if (neg) {
209                                 sysctl_sched_features &= ~(1UL << i);
210                                 sched_feat_disable(i);
211                         } else {
212                                 sysctl_sched_features |= (1UL << i);
213                                 sched_feat_enable(i);
214                         }
215                         break;
216                 }
217         }
218 
219         return i;
220 }
221 
222 static ssize_t
223 sched_feat_write(struct file *filp, const char __user *ubuf,
224                 size_t cnt, loff_t *ppos)
225 {
226         char buf[64];
227         char *cmp;
228         int i;
229 
230         if (cnt > 63)
231                 cnt = 63;
232 
233         if (copy_from_user(&buf, ubuf, cnt))
234                 return -EFAULT;
235 
236         buf[cnt] = 0;
237         cmp = strstrip(buf);
238 
239         i = sched_feat_set(cmp);
240         if (i == __SCHED_FEAT_NR)
241                 return -EINVAL;
242 
243         *ppos += cnt;
244 
245         return cnt;
246 }
247 
248 static int sched_feat_open(struct inode *inode, struct file *filp)
249 {
250         return single_open(filp, sched_feat_show, NULL);
251 }
252 
253 static const struct file_operations sched_feat_fops = {
254         .open           = sched_feat_open,
255         .write          = sched_feat_write,
256         .read           = seq_read,
257         .llseek         = seq_lseek,
258         .release        = single_release,
259 };
260 
261 static __init int sched_init_debug(void)
262 {
263         debugfs_create_file("sched_features", 0644, NULL, NULL,
264                         &sched_feat_fops);
265 
266         return 0;
267 }
268 late_initcall(sched_init_debug);
269 #endif /* CONFIG_SCHED_DEBUG */
270 
271 /*
272  * Number of tasks to iterate in a single balance run.
273  * Limited because this is done with IRQs disabled.
274  */
275 const_debug unsigned int sysctl_sched_nr_migrate = 32;
276 
277 /*
278  * period over which we average the RT time consumption, measured
279  * in ms.
280  *
281  * default: 1s
282  */
283 const_debug unsigned int sysctl_sched_time_avg = MSEC_PER_SEC;
284 
285 /*
286  * period over which we measure -rt task cpu usage in us.
287  * default: 1s
288  */
289 unsigned int sysctl_sched_rt_period = 1000000;
290 
291 __read_mostly int scheduler_running;
292 
293 /*
294  * part of the period that we allow rt tasks to run in us.
295  * default: 0.95s
296  */
297 int sysctl_sched_rt_runtime = 950000;
298 
299 
300 
301 /*
302  * __task_rq_lock - lock the rq @p resides on.
303  */
304 static inline struct rq *__task_rq_lock(struct task_struct *p)
305         __acquires(rq->lock)
306 {
307         struct rq *rq;
308 
309         lockdep_assert_held(&p->pi_lock);
310 
311         for (;;) {
312                 rq = task_rq(p);
313                 raw_spin_lock(&rq->lock);
314                 if (likely(rq == task_rq(p)))
315                         return rq;
316                 raw_spin_unlock(&rq->lock);
317         }
318 }
319 
320 /*
321  * task_rq_lock - lock p->pi_lock and lock the rq @p resides on.
322  */
323 static struct rq *task_rq_lock(struct task_struct *p, unsigned long *flags)
324         __acquires(p->pi_lock)
325         __acquires(rq->lock)
326 {
327         struct rq *rq;
328 
329         for (;;) {
330                 raw_spin_lock_irqsave(&p->pi_lock, *flags);
331                 rq = task_rq(p);
332                 raw_spin_lock(&rq->lock);
333                 if (likely(rq == task_rq(p)))
334                         return rq;
335                 raw_spin_unlock(&rq->lock);
336                 raw_spin_unlock_irqrestore(&p->pi_lock, *flags);
337         }
338 }
339 
340 static void __task_rq_unlock(struct rq *rq)
341         __releases(rq->lock)
342 {
343         raw_spin_unlock(&rq->lock);
344 }
345 
346 static inline void
347 task_rq_unlock(struct rq *rq, struct task_struct *p, unsigned long *flags)
348         __releases(rq->lock)
349         __releases(p->pi_lock)
350 {
351         raw_spin_unlock(&rq->lock);
352         raw_spin_unlock_irqrestore(&p->pi_lock, *flags);
353 }
354 
355 /*
356  * this_rq_lock - lock this runqueue and disable interrupts.
357  */
358 static struct rq *this_rq_lock(void)
359         __acquires(rq->lock)
360 {
361         struct rq *rq;
362 
363         local_irq_disable();
364         rq = this_rq();
365         raw_spin_lock(&rq->lock);
366 
367         return rq;
368 }
369 
370 #ifdef CONFIG_SCHED_HRTICK
371 /*
372  * Use HR-timers to deliver accurate preemption points.
373  */
374 
375 static void hrtick_clear(struct rq *rq)
376 {
377         if (hrtimer_active(&rq->hrtick_timer))
378                 hrtimer_cancel(&rq->hrtick_timer);
379 }
380 
381 /*
382  * High-resolution timer tick.
383  * Runs from hardirq context with interrupts disabled.
384  */
385 static enum hrtimer_restart hrtick(struct hrtimer *timer)
386 {
387         struct rq *rq = container_of(timer, struct rq, hrtick_timer);
388 
389         WARN_ON_ONCE(cpu_of(rq) != smp_processor_id());
390 
391         raw_spin_lock(&rq->lock);
392         update_rq_clock(rq);
393         rq->curr->sched_class->task_tick(rq, rq->curr, 1);
394         raw_spin_unlock(&rq->lock);
395 
396         return HRTIMER_NORESTART;
397 }
398 
399 #ifdef CONFIG_SMP
400 
401 static int __hrtick_restart(struct rq *rq)
402 {
403         struct hrtimer *timer = &rq->hrtick_timer;
404         ktime_t time = hrtimer_get_softexpires(timer);
405 
406         return __hrtimer_start_range_ns(timer, time, 0, HRTIMER_MODE_ABS_PINNED, 0);
407 }
408 
409 /*
410  * called from hardirq (IPI) context
411  */
412 static void __hrtick_start(void *arg)
413 {
414         struct rq *rq = arg;
415 
416         raw_spin_lock(&rq->lock);
417         __hrtick_restart(rq);
418         rq->hrtick_csd_pending = 0;
419         raw_spin_unlock(&rq->lock);
420 }
421 
422 /*
423  * Called to set the hrtick timer state.
424  *
425  * called with rq->lock held and irqs disabled
426  */
427 void hrtick_start(struct rq *rq, u64 delay)
428 {
429         struct hrtimer *timer = &rq->hrtick_timer;
430         ktime_t time = ktime_add_ns(timer->base->get_time(), delay);
431 
432         hrtimer_set_expires(timer, time);
433 
434         if (rq == this_rq()) {
435                 __hrtick_restart(rq);
436         } else if (!rq->hrtick_csd_pending) {
437                 __smp_call_function_single(cpu_of(rq), &rq->hrtick_csd, 0);
438                 rq->hrtick_csd_pending = 1;
439         }
440 }
441 
442 static int
443 hotplug_hrtick(struct notifier_block *nfb, unsigned long action, void *hcpu)
444 {
445         int cpu = (int)(long)hcpu;
446 
447         switch (action) {
448         case CPU_UP_CANCELED:
449         case CPU_UP_CANCELED_FROZEN:
450         case CPU_DOWN_PREPARE:
451         case CPU_DOWN_PREPARE_FROZEN:
452         case CPU_DEAD:
453         case CPU_DEAD_FROZEN:
454                 hrtick_clear(cpu_rq(cpu));
455                 return NOTIFY_OK;
456         }
457 
458         return NOTIFY_DONE;
459 }
460 
461 static __init void init_hrtick(void)
462 {
463         hotcpu_notifier(hotplug_hrtick, 0);
464 }
465 #else
466 /*
467  * Called to set the hrtick timer state.
468  *
469  * called with rq->lock held and irqs disabled
470  */
471 void hrtick_start(struct rq *rq, u64 delay)
472 {
473         __hrtimer_start_range_ns(&rq->hrtick_timer, ns_to_ktime(delay), 0,
474                         HRTIMER_MODE_REL_PINNED, 0);
475 }
476 
477 static inline void init_hrtick(void)
478 {
479 }
480 #endif /* CONFIG_SMP */
481 
482 static void init_rq_hrtick(struct rq *rq)
483 {
484 #ifdef CONFIG_SMP
485         rq->hrtick_csd_pending = 0;
486 
487         rq->hrtick_csd.flags = 0;
488         rq->hrtick_csd.func = __hrtick_start;
489         rq->hrtick_csd.info = rq;
490 #endif
491 
492         hrtimer_init(&rq->hrtick_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
493         rq->hrtick_timer.function = hrtick;
494 }
495 #else   /* CONFIG_SCHED_HRTICK */
496 static inline void hrtick_clear(struct rq *rq)
497 {
498 }
499 
500 static inline void init_rq_hrtick(struct rq *rq)
501 {
502 }
503 
504 static inline void init_hrtick(void)
505 {
506 }
507 #endif  /* CONFIG_SCHED_HRTICK */
508 
509 /*
510  * resched_task - mark a task 'to be rescheduled now'.
511  *
512  * On UP this means the setting of the need_resched flag, on SMP it
513  * might also involve a cross-CPU call to trigger the scheduler on
514  * the target CPU.
515  */
516 void resched_task(struct task_struct *p)
517 {
518         int cpu;
519 
520         lockdep_assert_held(&task_rq(p)->lock);
521 
522         if (test_tsk_need_resched(p))
523                 return;
524 
525         set_tsk_need_resched(p);
526 
527         cpu = task_cpu(p);
528         if (cpu == smp_processor_id()) {
529                 set_preempt_need_resched();
530                 return;
531         }
532 
533         /* NEED_RESCHED must be visible before we test polling */
534         smp_mb();
535         if (!tsk_is_polling(p))
536                 smp_send_reschedule(cpu);
537 }
538 
539 void resched_cpu(int cpu)
540 {
541         struct rq *rq = cpu_rq(cpu);
542         unsigned long flags;
543 
544         if (!raw_spin_trylock_irqsave(&rq->lock, flags))
545                 return;
546         resched_task(cpu_curr(cpu));
547         raw_spin_unlock_irqrestore(&rq->lock, flags);
548 }
549 
550 #ifdef CONFIG_SMP
551 #ifdef CONFIG_NO_HZ_COMMON
552 /*
553  * In the semi idle case, use the nearest busy cpu for migrating timers
554  * from an idle cpu.  This is good for power-savings.
555  *
556  * We don't do similar optimization for completely idle system, as
557  * selecting an idle cpu will add more delays to the timers than intended
558  * (as that cpu's timer base may not be uptodate wrt jiffies etc).
559  */
560 int get_nohz_timer_target(void)
561 {
562         int cpu = smp_processor_id();
563         int i;
564         struct sched_domain *sd;
565 
566         rcu_read_lock();
567         for_each_domain(cpu, sd) {
568                 for_each_cpu(i, sched_domain_span(sd)) {
569                         if (!idle_cpu(i)) {
570                                 cpu = i;
571                                 goto unlock;
572                         }
573                 }
574         }
575 unlock:
576         rcu_read_unlock();
577         return cpu;
578 }
579 /*
580  * When add_timer_on() enqueues a timer into the timer wheel of an
581  * idle CPU then this timer might expire before the next timer event
582  * which is scheduled to wake up that CPU. In case of a completely
583  * idle system the next event might even be infinite time into the
584  * future. wake_up_idle_cpu() ensures that the CPU is woken up and
585  * leaves the inner idle loop so the newly added timer is taken into
586  * account when the CPU goes back to idle and evaluates the timer
587  * wheel for the next timer event.
588  */
589 static void wake_up_idle_cpu(int cpu)
590 {
591         struct rq *rq = cpu_rq(cpu);
592 
593         if (cpu == smp_processor_id())
594                 return;
595 
596         /*
597          * This is safe, as this function is called with the timer
598          * wheel base lock of (cpu) held. When the CPU is on the way
599          * to idle and has not yet set rq->curr to idle then it will
600          * be serialized on the timer wheel base lock and take the new
601          * timer into account automatically.
602          */
603         if (rq->curr != rq->idle)
604                 return;
605 
606         /*
607          * We can set TIF_RESCHED on the idle task of the other CPU
608          * lockless. The worst case is that the other CPU runs the
609          * idle task through an additional NOOP schedule()
610          */
611         set_tsk_need_resched(rq->idle);
612 
613         /* NEED_RESCHED must be visible before we test polling */
614         smp_mb();
615         if (!tsk_is_polling(rq->idle))
616                 smp_send_reschedule(cpu);
617 }
618 
619 static bool wake_up_full_nohz_cpu(int cpu)
620 {
621         if (tick_nohz_full_cpu(cpu)) {
622                 if (cpu != smp_processor_id() ||
623                     tick_nohz_tick_stopped())
624                         smp_send_reschedule(cpu);
625                 return true;
626         }
627 
628         return false;
629 }
630 
631 void wake_up_nohz_cpu(int cpu)
632 {
633         if (!wake_up_full_nohz_cpu(cpu))
634                 wake_up_idle_cpu(cpu);
635 }
636 
637 static inline bool got_nohz_idle_kick(void)
638 {
639         int cpu = smp_processor_id();
640 
641         if (!test_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu)))
642                 return false;
643 
644         if (idle_cpu(cpu) && !need_resched())
645                 return true;
646 
647         /*
648          * We can't run Idle Load Balance on this CPU for this time so we
649          * cancel it and clear NOHZ_BALANCE_KICK
650          */
651         clear_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu));
652         return false;
653 }
654 
655 #else /* CONFIG_NO_HZ_COMMON */
656 
657 static inline bool got_nohz_idle_kick(void)
658 {
659         return false;
660 }
661 
662 #endif /* CONFIG_NO_HZ_COMMON */
663 
664 #ifdef CONFIG_NO_HZ_FULL
665 bool sched_can_stop_tick(void)
666 {
667        struct rq *rq;
668 
669        rq = this_rq();
670 
671        /* Make sure rq->nr_running update is visible after the IPI */
672        smp_rmb();
673 
674        /* More than one running task need preemption */
675        if (rq->nr_running > 1)
676                return false;
677 
678        return true;
679 }
680 #endif /* CONFIG_NO_HZ_FULL */
681 
682 void sched_avg_update(struct rq *rq)
683 {
684         s64 period = sched_avg_period();
685 
686         while ((s64)(rq_clock(rq) - rq->age_stamp) > period) {
687                 /*
688                  * Inline assembly required to prevent the compiler
689                  * optimising this loop into a divmod call.
690                  * See __iter_div_u64_rem() for another example of this.
691                  */
692                 asm("" : "+rm" (rq->age_stamp));
693                 rq->age_stamp += period;
694                 rq->rt_avg /= 2;
695         }
696 }
697 
698 #endif /* CONFIG_SMP */
699 
700 #if defined(CONFIG_RT_GROUP_SCHED) || (defined(CONFIG_FAIR_GROUP_SCHED) && \
701                         (defined(CONFIG_SMP) || defined(CONFIG_CFS_BANDWIDTH)))
702 /*
703  * Iterate task_group tree rooted at *from, calling @down when first entering a
704  * node and @up when leaving it for the final time.
705  *
706  * Caller must hold rcu_lock or sufficient equivalent.
707  */
708 int walk_tg_tree_from(struct task_group *from,
709                              tg_visitor down, tg_visitor up, void *data)
710 {
711         struct task_group *parent, *child;
712         int ret;
713 
714         parent = from;
715 
716 down:
717         ret = (*down)(parent, data);
718         if (ret)
719                 goto out;
720         list_for_each_entry_rcu(child, &parent->children, siblings) {
721                 parent = child;
722                 goto down;
723 
724 up:
725                 continue;
726         }
727         ret = (*up)(parent, data);
728         if (ret || parent == from)
729                 goto out;
730 
731         child = parent;
732         parent = parent->parent;
733         if (parent)
734                 goto up;
735 out:
736         return ret;
737 }
738 
739 int tg_nop(struct task_group *tg, void *data)
740 {
741         return 0;
742 }
743 #endif
744 
745 static void set_load_weight(struct task_struct *p)
746 {
747         int prio = p->static_prio - MAX_RT_PRIO;
748         struct load_weight *load = &p->se.load;
749 
750         /*
751          * SCHED_IDLE tasks get minimal weight:
752          */
753         if (p->policy == SCHED_IDLE) {
754                 load->weight = scale_load(WEIGHT_IDLEPRIO);
755                 load->inv_weight = WMULT_IDLEPRIO;
756                 return;
757         }
758 
759         load->weight = scale_load(prio_to_weight[prio]);
760         load->inv_weight = prio_to_wmult[prio];
761 }
762 
763 static void enqueue_task(struct rq *rq, struct task_struct *p, int flags)
764 {
765         update_rq_clock(rq);
766         sched_info_queued(rq, p);
767         p->sched_class->enqueue_task(rq, p, flags);
768 }
769 
770 static void dequeue_task(struct rq *rq, struct task_struct *p, int flags)
771 {
772         update_rq_clock(rq);
773         sched_info_dequeued(rq, p);
774         p->sched_class->dequeue_task(rq, p, flags);
775 }
776 
777 void activate_task(struct rq *rq, struct task_struct *p, int flags)
778 {
779         if (task_contributes_to_load(p))
780                 rq->nr_uninterruptible--;
781 
782         enqueue_task(rq, p, flags);
783 }
784 
785 void deactivate_task(struct rq *rq, struct task_struct *p, int flags)
786 {
787         if (task_contributes_to_load(p))
788                 rq->nr_uninterruptible++;
789 
790         dequeue_task(rq, p, flags);
791 }
792 
793 static void update_rq_clock_task(struct rq *rq, s64 delta)
794 {
795 /*
796  * In theory, the compile should just see 0 here, and optimize out the call
797  * to sched_rt_avg_update. But I don't trust it...
798  */
799 #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
800         s64 steal = 0, irq_delta = 0;
801 #endif
802 #ifdef CONFIG_IRQ_TIME_ACCOUNTING
803         irq_delta = irq_time_read(cpu_of(rq)) - rq->prev_irq_time;
804 
805         /*
806          * Since irq_time is only updated on {soft,}irq_exit, we might run into
807          * this case when a previous update_rq_clock() happened inside a
808          * {soft,}irq region.
809          *
810          * When this happens, we stop ->clock_task and only update the
811          * prev_irq_time stamp to account for the part that fit, so that a next
812          * update will consume the rest. This ensures ->clock_task is
813          * monotonic.
814          *
815          * It does however cause some slight miss-attribution of {soft,}irq
816          * time, a more accurate solution would be to update the irq_time using
817          * the current rq->clock timestamp, except that would require using
818          * atomic ops.
819          */
820         if (irq_delta > delta)
821                 irq_delta = delta;
822 
823         rq->prev_irq_time += irq_delta;
824         delta -= irq_delta;
825 #endif
826 #ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
827         if (static_key_false((&paravirt_steal_rq_enabled))) {
828                 u64 st;
829 
830                 steal = paravirt_steal_clock(cpu_of(rq));
831                 steal -= rq->prev_steal_time_rq;
832 
833                 if (unlikely(steal > delta))
834                         steal = delta;
835 
836                 st = steal_ticks(steal);
837                 steal = st * TICK_NSEC;
838 
839                 rq->prev_steal_time_rq += steal;
840 
841                 delta -= steal;
842         }
843 #endif
844 
845         rq->clock_task += delta;
846 
847 #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
848         if ((irq_delta + steal) && sched_feat(NONTASK_POWER))
849                 sched_rt_avg_update(rq, irq_delta + steal);
850 #endif
851 }
852 
853 void sched_set_stop_task(int cpu, struct task_struct *stop)
854 {
855         struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
856         struct task_struct *old_stop = cpu_rq(cpu)->stop;
857 
858         if (stop) {
859                 /*
860                  * Make it appear like a SCHED_FIFO task, its something
861                  * userspace knows about and won't get confused about.
862                  *
863                  * Also, it will make PI more or less work without too
864                  * much confusion -- but then, stop work should not
865                  * rely on PI working anyway.
866                  */
867                 sched_setscheduler_nocheck(stop, SCHED_FIFO, &param);
868 
869                 stop->sched_class = &stop_sched_class;
870         }
871 
872         cpu_rq(cpu)->stop = stop;
873 
874         if (old_stop) {
875                 /*
876                  * Reset it back to a normal scheduling class so that
877                  * it can die in pieces.
878                  */
879                 old_stop->sched_class = &rt_sched_class;
880         }
881 }
882 
883 /*
884  * __normal_prio - return the priority that is based on the static prio
885  */
886 static inline int __normal_prio(struct task_struct *p)
887 {
888         return p->static_prio;
889 }
890 
891 /*
892  * Calculate the expected normal priority: i.e. priority
893  * without taking RT-inheritance into account. Might be
894  * boosted by interactivity modifiers. Changes upon fork,
895  * setprio syscalls, and whenever the interactivity
896  * estimator recalculates.
897  */
898 static inline int normal_prio(struct task_struct *p)
899 {
900         int prio;
901 
902         if (task_has_rt_policy(p))
903                 prio = MAX_RT_PRIO-1 - p->rt_priority;
904         else
905                 prio = __normal_prio(p);
906         return prio;
907 }
908 
909 /*
910  * Calculate the current priority, i.e. the priority
911  * taken into account by the scheduler. This value might
912  * be boosted by RT tasks, or might be boosted by
913  * interactivity modifiers. Will be RT if the task got
914  * RT-boosted. If not then it returns p->normal_prio.
915  */
916 static int effective_prio(struct task_struct *p)
917 {
918         p->normal_prio = normal_prio(p);
919         /*
920          * If we are RT tasks or we were boosted to RT priority,
921          * keep the priority unchanged. Otherwise, update priority
922          * to the normal priority:
923          */
924         if (!rt_prio(p->prio))
925                 return p->normal_prio;
926         return p->prio;
927 }
928 
929 /**
930  * task_curr - is this task currently executing on a CPU?
931  * @p: the task in question.
932  *
933  * Return: 1 if the task is currently executing. 0 otherwise.
934  */
935 inline int task_curr(const struct task_struct *p)
936 {
937         return cpu_curr(task_cpu(p)) == p;
938 }
939 
940 static inline void check_class_changed(struct rq *rq, struct task_struct *p,
941                                        const struct sched_class *prev_class,
942                                        int oldprio)
943 {
944         if (prev_class != p->sched_class) {
945                 if (prev_class->switched_from)
946                         prev_class->switched_from(rq, p);
947                 p->sched_class->switched_to(rq, p);
948         } else if (oldprio != p->prio)
949                 p->sched_class->prio_changed(rq, p, oldprio);
950 }
951 
952 void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags)
953 {
954         const struct sched_class *class;
955 
956         if (p->sched_class == rq->curr->sched_class) {
957                 rq->curr->sched_class->check_preempt_curr(rq, p, flags);
958         } else {
959                 for_each_class(class) {
960                         if (class == rq->curr->sched_class)
961                                 break;
962                         if (class == p->sched_class) {
963                                 resched_task(rq->curr);
964                                 break;
965                         }
966                 }
967         }
968 
969         /*
970          * A queue event has occurred, and we're going to schedule.  In
971          * this case, we can save a useless back to back clock update.
972          */
973         if (rq->curr->on_rq && test_tsk_need_resched(rq->curr))
974                 rq->skip_clock_update = 1;
975 }
976 
977 #ifdef CONFIG_SMP
978 void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
979 {
980 #ifdef CONFIG_SCHED_DEBUG
981         /*
982          * We should never call set_task_cpu() on a blocked task,
983          * ttwu() will sort out the placement.
984          */
985         WARN_ON_ONCE(p->state != TASK_RUNNING && p->state != TASK_WAKING &&
986                         !(task_preempt_count(p) & PREEMPT_ACTIVE));
987 
988 #ifdef CONFIG_LOCKDEP
989         /*
990          * The caller should hold either p->pi_lock or rq->lock, when changing
991          * a task's CPU. ->pi_lock for waking tasks, rq->lock for runnable tasks.
992          *
993          * sched_move_task() holds both and thus holding either pins the cgroup,
994          * see task_group().
995          *
996          * Furthermore, all task_rq users should acquire both locks, see
997          * task_rq_lock().
998          */
999         WARN_ON_ONCE(debug_locks && !(lockdep_is_held(&p->pi_lock) ||
1000                                       lockdep_is_held(&task_rq(p)->lock)));
1001 #endif
1002 #endif
1003 
1004         trace_sched_migrate_task(p, new_cpu);
1005 
1006         if (task_cpu(p) != new_cpu) {
1007                 if (p->sched_class->migrate_task_rq)
1008                         p->sched_class->migrate_task_rq(p, new_cpu);
1009                 p->se.nr_migrations++;
1010                 perf_sw_event(PERF_COUNT_SW_CPU_MIGRATIONS, 1, NULL, 0);
1011         }
1012 
1013         __set_task_cpu(p, new_cpu);
1014 }
1015 
1016 static void __migrate_swap_task(struct task_struct *p, int cpu)
1017 {
1018         if (p->on_rq) {
1019                 struct rq *src_rq, *dst_rq;
1020 
1021                 src_rq = task_rq(p);
1022                 dst_rq = cpu_rq(cpu);
1023 
1024                 deactivate_task(src_rq, p, 0);
1025                 set_task_cpu(p, cpu);
1026                 activate_task(dst_rq, p, 0);
1027                 check_preempt_curr(dst_rq, p, 0);
1028         } else {
1029                 /*
1030                  * Task isn't running anymore; make it appear like we migrated
1031                  * it before it went to sleep. This means on wakeup we make the
1032                  * previous cpu our targer instead of where it really is.
1033                  */
1034                 p->wake_cpu = cpu;
1035         }
1036 }
1037 
1038 struct migration_swap_arg {
1039         struct task_struct *src_task, *dst_task;
1040         int src_cpu, dst_cpu;
1041 };
1042 
1043 static int migrate_swap_stop(void *data)
1044 {
1045         struct migration_swap_arg *arg = data;
1046         struct rq *src_rq, *dst_rq;
1047         int ret = -EAGAIN;
1048 
1049         src_rq = cpu_rq(arg->src_cpu);
1050         dst_rq = cpu_rq(arg->dst_cpu);
1051 
1052         double_raw_lock(&arg->src_task->pi_lock,
1053                         &arg->dst_task->pi_lock);
1054         double_rq_lock(src_rq, dst_rq);
1055         if (task_cpu(arg->dst_task) != arg->dst_cpu)
1056                 goto unlock;
1057 
1058         if (task_cpu(arg->src_task) != arg->src_cpu)
1059                 goto unlock;
1060 
1061         if (!cpumask_test_cpu(arg->dst_cpu, tsk_cpus_allowed(arg->src_task)))
1062                 goto unlock;
1063 
1064         if (!cpumask_test_cpu(arg->src_cpu, tsk_cpus_allowed(arg->dst_task)))
1065                 goto unlock;
1066 
1067         __migrate_swap_task(arg->src_task, arg->dst_cpu);
1068         __migrate_swap_task(arg->dst_task, arg->src_cpu);
1069 
1070         ret = 0;
1071 
1072 unlock:
1073         double_rq_unlock(src_rq, dst_rq);
1074         raw_spin_unlock(&arg->dst_task->pi_lock);
1075         raw_spin_unlock(&arg->src_task->pi_lock);
1076 
1077         return ret;
1078 }
1079 
1080 /*
1081  * Cross migrate two tasks
1082  */
1083 int migrate_swap(struct task_struct *cur, struct task_struct *p)
1084 {
1085         struct migration_swap_arg arg;
1086         int ret = -EINVAL;
1087 
1088         arg = (struct migration_swap_arg){
1089                 .src_task = cur,
1090                 .src_cpu = task_cpu(cur),
1091                 .dst_task = p,
1092                 .dst_cpu = task_cpu(p),
1093         };
1094 
1095         if (arg.src_cpu == arg.dst_cpu)
1096                 goto out;
1097 
1098         /*
1099          * These three tests are all lockless; this is OK since all of them
1100          * will be re-checked with proper locks held further down the line.
1101          */
1102         if (!cpu_active(arg.src_cpu) || !cpu_active(arg.dst_cpu))
1103                 goto out;
1104 
1105         if (!cpumask_test_cpu(arg.dst_cpu, tsk_cpus_allowed(arg.src_task)))
1106                 goto out;
1107 
1108         if (!cpumask_test_cpu(arg.src_cpu, tsk_cpus_allowed(arg.dst_task)))
1109                 goto out;
1110 
1111         ret = stop_two_cpus(arg.dst_cpu, arg.src_cpu, migrate_swap_stop, &arg);
1112 
1113 out:
1114         return ret;
1115 }
1116 
1117 struct migration_arg {
1118         struct task_struct *task;
1119         int dest_cpu;
1120 };
1121 
1122 static int migration_cpu_stop(void *data);
1123 
1124 /*
1125  * wait_task_inactive - wait for a thread to unschedule.
1126  *
1127  * If @match_state is nonzero, it's the @p->state value just checked and
1128  * not expected to change.  If it changes, i.e. @p might have woken up,
1129  * then return zero.  When we succeed in waiting for @p to be off its CPU,
1130  * we return a positive number (its total switch count).  If a second call
1131  * a short while later returns the same number, the caller can be sure that
1132  * @p has remained unscheduled the whole time.
1133  *
1134  * The caller must ensure that the task *will* unschedule sometime soon,
1135  * else this function might spin for a *long* time. This function can't
1136  * be called with interrupts off, or it may introduce deadlock with
1137  * smp_call_function() if an IPI is sent by the same process we are
1138  * waiting to become inactive.
1139  */
1140 unsigned long wait_task_inactive(struct task_struct *p, long match_state)
1141 {
1142         unsigned long flags;
1143         int running, on_rq;
1144         unsigned long ncsw;
1145         struct rq *rq;
1146 
1147         for (;;) {
1148                 /*
1149                  * We do the initial early heuristics without holding
1150                  * any task-queue locks at all. We'll only try to get
1151                  * the runqueue lock when things look like they will
1152                  * work out!
1153                  */
1154                 rq = task_rq(p);
1155 
1156                 /*
1157                  * If the task is actively running on another CPU
1158                  * still, just relax and busy-wait without holding
1159                  * any locks.
1160                  *
1161                  * NOTE! Since we don't hold any locks, it's not
1162                  * even sure that "rq" stays as the right runqueue!
1163                  * But we don't care, since "task_running()" will
1164                  * return false if the runqueue has changed and p
1165                  * is actually now running somewhere else!
1166                  */
1167                 while (task_running(rq, p)) {
1168                         if (match_state && unlikely(p->state != match_state))
1169                                 return 0;
1170                         cpu_relax();
1171                 }
1172 
1173                 /*
1174                  * Ok, time to look more closely! We need the rq
1175                  * lock now, to be *sure*. If we're wrong, we'll
1176                  * just go back and repeat.
1177                  */
1178                 rq = task_rq_lock(p, &flags);
1179                 trace_sched_wait_task(p);
1180                 running = task_running(rq, p);
1181                 on_rq = p->on_rq;
1182                 ncsw = 0;
1183                 if (!match_state || p->state == match_state)
1184                         ncsw = p->nvcsw | LONG_MIN; /* sets MSB */
1185                 task_rq_unlock(rq, p, &flags);
1186 
1187                 /*
1188                  * If it changed from the expected state, bail out now.
1189                  */
1190                 if (unlikely(!ncsw))
1191                         break;
1192 
1193                 /*
1194                  * Was it really running after all now that we
1195                  * checked with the proper locks actually held?
1196                  *
1197                  * Oops. Go back and try again..
1198                  */
1199                 if (unlikely(running)) {
1200                         cpu_relax();
1201                         continue;
1202                 }
1203 
1204                 /*
1205                  * It's not enough that it's not actively running,
1206                  * it must be off the runqueue _entirely_, and not
1207                  * preempted!
1208                  *
1209                  * So if it was still runnable (but just not actively
1210                  * running right now), it's preempted, and we should
1211                  * yield - it could be a while.
1212                  */
1213                 if (unlikely(on_rq)) {
1214                         ktime_t to = ktime_set(0, NSEC_PER_SEC/HZ);
1215 
1216                         set_current_state(TASK_UNINTERRUPTIBLE);
1217                         schedule_hrtimeout(&to, HRTIMER_MODE_REL);
1218                         continue;
1219                 }
1220 
1221                 /*
1222                  * Ahh, all good. It wasn't running, and it wasn't
1223                  * runnable, which means that it will never become
1224                  * running in the future either. We're all done!
1225                  */
1226                 break;
1227         }
1228 
1229         return ncsw;
1230 }
1231 
1232 /***
1233  * kick_process - kick a running thread to enter/exit the kernel
1234  * @p: the to-be-kicked thread
1235  *
1236  * Cause a process which is running on another CPU to enter
1237  * kernel-mode, without any delay. (to get signals handled.)
1238  *
1239  * NOTE: this function doesn't have to take the runqueue lock,
1240  * because all it wants to ensure is that the remote task enters
1241  * the kernel. If the IPI races and the task has been migrated
1242  * to another CPU then no harm is done and the purpose has been
1243  * achieved as well.
1244  */
1245 void kick_process(struct task_struct *p)
1246 {
1247         int cpu;
1248 
1249         preempt_disable();
1250         cpu = task_cpu(p);
1251         if ((cpu != smp_processor_id()) && task_curr(p))
1252                 smp_send_reschedule(cpu);
1253         preempt_enable();
1254 }
1255 EXPORT_SYMBOL_GPL(kick_process);
1256 #endif /* CONFIG_SMP */
1257 
1258 #ifdef CONFIG_SMP
1259 /*
1260  * ->cpus_allowed is protected by both rq->lock and p->pi_lock
1261  */
1262 static int select_fallback_rq(int cpu, struct task_struct *p)
1263 {
1264         int nid = cpu_to_node(cpu);
1265         const struct cpumask *nodemask = NULL;
1266         enum { cpuset, possible, fail } state = cpuset;
1267         int dest_cpu;
1268 
1269         /*
1270          * If the node that the cpu is on has been offlined, cpu_to_node()
1271          * will return -1. There is no cpu on the node, and we should
1272          * select the cpu on the other node.
1273          */
1274         if (nid != -1) {
1275                 nodemask = cpumask_of_node(nid);
1276 
1277                 /* Look for allowed, online CPU in same node. */
1278                 for_each_cpu(dest_cpu, nodemask) {
1279                         if (!cpu_online(dest_cpu))
1280                                 continue;
1281                         if (!cpu_active(dest_cpu))
1282                                 continue;
1283                         if (cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p)))
1284                                 return dest_cpu;
1285                 }
1286         }
1287 
1288         for (;;) {
1289                 /* Any allowed, online CPU? */
1290                 for_each_cpu(dest_cpu, tsk_cpus_allowed(p)) {
1291                         if (!cpu_online(dest_cpu))
1292                                 continue;
1293                         if (!cpu_active(dest_cpu))
1294                                 continue;
1295                         goto out;
1296                 }
1297 
1298                 switch (state) {
1299                 case cpuset:
1300                         /* No more Mr. Nice Guy. */
1301                         cpuset_cpus_allowed_fallback(p);
1302                         state = possible;
1303                         break;
1304 
1305                 case possible:
1306                         do_set_cpus_allowed(p, cpu_possible_mask);
1307                         state = fail;
1308                         break;
1309 
1310                 case fail:
1311                         BUG();
1312                         break;
1313                 }
1314         }
1315 
1316 out:
1317         if (state != cpuset) {
1318                 /*
1319                  * Don't tell them about moving exiting tasks or
1320                  * kernel threads (both mm NULL), since they never
1321                  * leave kernel.
1322                  */
1323                 if (p->mm && printk_ratelimit()) {
1324                         printk_sched("process %d (%s) no longer affine to cpu%d\n",
1325                                         task_pid_nr(p), p->comm, cpu);
1326                 }
1327         }
1328 
1329         return dest_cpu;
1330 }
1331 
1332 /*
1333  * The caller (fork, wakeup) owns p->pi_lock, ->cpus_allowed is stable.
1334  */
1335 static inline
1336 int select_task_rq(struct task_struct *p, int cpu, int sd_flags, int wake_flags)
1337 {
1338         cpu = p->sched_class->select_task_rq(p, cpu, sd_flags, wake_flags);
1339 
1340         /*
1341          * In order not to call set_task_cpu() on a blocking task we need
1342          * to rely on ttwu() to place the task on a valid ->cpus_allowed
1343          * cpu.
1344          *
1345          * Since this is common to all placement strategies, this lives here.
1346          *
1347          * [ this allows ->select_task() to simply return task_cpu(p) and
1348          *   not worry about this generic constraint ]
1349          */
1350         if (unlikely(!cpumask_test_cpu(cpu, tsk_cpus_allowed(p)) ||
1351                      !cpu_online(cpu)))
1352                 cpu = select_fallback_rq(task_cpu(p), p);
1353 
1354         return cpu;
1355 }
1356 
1357 static void update_avg(u64 *avg, u64 sample)
1358 {
1359         s64 diff = sample - *avg;
1360         *avg += diff >> 3;
1361 }
1362 #endif
1363 
1364 static void
1365 ttwu_stat(struct task_struct *p, int cpu, int wake_flags)
1366 {
1367 #ifdef CONFIG_SCHEDSTATS
1368         struct rq *rq = this_rq();
1369 
1370 #ifdef CONFIG_SMP
1371         int this_cpu = smp_processor_id();
1372 
1373         if (cpu == this_cpu) {
1374                 schedstat_inc(rq, ttwu_local);
1375                 schedstat_inc(p, se.statistics.nr_wakeups_local);
1376         } else {
1377                 struct sched_domain *sd;
1378 
1379                 schedstat_inc(p, se.statistics.nr_wakeups_remote);
1380                 rcu_read_lock();
1381                 for_each_domain(this_cpu, sd) {
1382                         if (cpumask_test_cpu(cpu, sched_domain_span(sd))) {
1383                                 schedstat_inc(sd, ttwu_wake_remote);
1384                                 break;
1385                         }
1386                 }
1387                 rcu_read_unlock();
1388         }
1389 
1390         if (wake_flags & WF_MIGRATED)
1391                 schedstat_inc(p, se.statistics.nr_wakeups_migrate);
1392 
1393 #endif /* CONFIG_SMP */
1394 
1395         schedstat_inc(rq, ttwu_count);
1396         schedstat_inc(p, se.statistics.nr_wakeups);
1397 
1398         if (wake_flags & WF_SYNC)
1399                 schedstat_inc(p, se.statistics.nr_wakeups_sync);
1400 
1401 #endif /* CONFIG_SCHEDSTATS */
1402 }
1403 
1404 static void ttwu_activate(struct rq *rq, struct task_struct *p, int en_flags)
1405 {
1406         activate_task(rq, p, en_flags);
1407         p->on_rq = 1;
1408 
1409         /* if a worker is waking up, notify workqueue */
1410         if (p->flags & PF_WQ_WORKER)
1411                 wq_worker_waking_up(p, cpu_of(rq));
1412 }
1413 
1414 /*
1415  * Mark the task runnable and perform wakeup-preemption.
1416  */
1417 static void
1418 ttwu_do_wakeup(struct rq *rq, struct task_struct *p, int wake_flags)
1419 {
1420         check_preempt_curr(rq, p, wake_flags);
1421         trace_sched_wakeup(p, true);
1422 
1423         p->state = TASK_RUNNING;
1424 #ifdef CONFIG_SMP
1425         if (p->sched_class->task_woken)
1426                 p->sched_class->task_woken(rq, p);
1427 
1428         if (rq->idle_stamp) {
1429                 u64 delta = rq_clock(rq) - rq->idle_stamp;
1430                 u64 max = 2*rq->max_idle_balance_cost;
1431 
1432                 update_avg(&rq->avg_idle, delta);
1433 
1434                 if (rq->avg_idle > max)
1435                         rq->avg_idle = max;
1436 
1437                 rq->idle_stamp = 0;
1438         }
1439 #endif
1440 }
1441 
1442 static void
1443 ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags)
1444 {
1445 #ifdef CONFIG_SMP
1446         if (p->sched_contributes_to_load)
1447                 rq->nr_uninterruptible--;
1448 #endif
1449 
1450         ttwu_activate(rq, p, ENQUEUE_WAKEUP | ENQUEUE_WAKING);
1451         ttwu_do_wakeup(rq, p, wake_flags);
1452 }
1453 
1454 /*
1455  * Called in case the task @p isn't fully descheduled from its runqueue,
1456  * in this case we must do a remote wakeup. Its a 'light' wakeup though,
1457  * since all we need to do is flip p->state to TASK_RUNNING, since
1458  * the task is still ->on_rq.
1459  */
1460 static int ttwu_remote(struct task_struct *p, int wake_flags)
1461 {
1462         struct rq *rq;
1463         int ret = 0;
1464 
1465         rq = __task_rq_lock(p);
1466         if (p->on_rq) {
1467                 /* check_preempt_curr() may use rq clock */
1468                 update_rq_clock(rq);
1469                 ttwu_do_wakeup(rq, p, wake_flags);
1470                 ret = 1;
1471         }
1472         __task_rq_unlock(rq);
1473 
1474         return ret;
1475 }
1476 
1477 #ifdef CONFIG_SMP
1478 static void sched_ttwu_pending(void)
1479 {
1480         struct rq *rq = this_rq();
1481         struct llist_node *llist = llist_del_all(&rq->wake_list);
1482         struct task_struct *p;
1483 
1484         raw_spin_lock(&rq->lock);
1485 
1486         while (llist) {
1487                 p = llist_entry(llist, struct task_struct, wake_entry);
1488                 llist = llist_next(llist);
1489                 ttwu_do_activate(rq, p, 0);
1490         }
1491 
1492         raw_spin_unlock(&rq->lock);
1493 }
1494 
1495 void scheduler_ipi(void)
1496 {
1497         /*
1498          * Fold TIF_NEED_RESCHED into the preempt_count; anybody setting
1499          * TIF_NEED_RESCHED remotely (for the first time) will also send
1500          * this IPI.
1501          */
1502         if (tif_need_resched())
1503                 set_preempt_need_resched();
1504 
1505         if (llist_empty(&this_rq()->wake_list)
1506                         && !tick_nohz_full_cpu(smp_processor_id())
1507                         && !got_nohz_idle_kick())
1508                 return;
1509 
1510         /*
1511          * Not all reschedule IPI handlers call irq_enter/irq_exit, since
1512          * traditionally all their work was done from the interrupt return
1513          * path. Now that we actually do some work, we need to make sure
1514          * we do call them.
1515          *
1516          * Some archs already do call them, luckily irq_enter/exit nest
1517          * properly.
1518          *
1519          * Arguably we should visit all archs and update all handlers,
1520          * however a fair share of IPIs are still resched only so this would
1521          * somewhat pessimize the simple resched case.
1522          */
1523         irq_enter();
1524         tick_nohz_full_check();
1525         sched_ttwu_pending();
1526 
1527         /*
1528          * Check if someone kicked us for doing the nohz idle load balance.
1529          */
1530         if (unlikely(got_nohz_idle_kick())) {
1531                 this_rq()->idle_balance = 1;
1532                 raise_softirq_irqoff(SCHED_SOFTIRQ);
1533         }
1534         irq_exit();
1535 }
1536 
1537 static void ttwu_queue_remote(struct task_struct *p, int cpu)
1538 {
1539         if (llist_add(&p->wake_entry, &cpu_rq(cpu)->wake_list))
1540                 smp_send_reschedule(cpu);
1541 }
1542 
1543 bool cpus_share_cache(int this_cpu, int that_cpu)
1544 {
1545         return per_cpu(sd_llc_id, this_cpu) == per_cpu(sd_llc_id, that_cpu);
1546 }
1547 #endif /* CONFIG_SMP */
1548 
1549 static void ttwu_queue(struct task_struct *p, int cpu)
1550 {
1551         struct rq *rq = cpu_rq(cpu);
1552 
1553 #if defined(CONFIG_SMP)
1554         if (sched_feat(TTWU_QUEUE) && !cpus_share_cache(smp_processor_id(), cpu)) {
1555                 sched_clock_cpu(cpu); /* sync clocks x-cpu */
1556                 ttwu_queue_remote(p, cpu);
1557                 return;
1558         }
1559 #endif
1560 
1561         raw_spin_lock(&rq->lock);
1562         ttwu_do_activate(rq, p, 0);
1563         raw_spin_unlock(&rq->lock);
1564 }
1565 
1566 /**
1567  * try_to_wake_up - wake up a thread
1568  * @p: the thread to be awakened
1569  * @state: the mask of task states that can be woken
1570  * @wake_flags: wake modifier flags (WF_*)
1571  *
1572  * Put it on the run-queue if it's not already there. The "current"
1573  * thread is always on the run-queue (except when the actual
1574  * re-schedule is in progress), and as such you're allowed to do
1575  * the simpler "current->state = TASK_RUNNING" to mark yourself
1576  * runnable without the overhead of this.
1577  *
1578  * Return: %true if @p was woken up, %false if it was already running.
1579  * or @state didn't match @p's state.
1580  */
1581 static int
1582 try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
1583 {
1584         unsigned long flags;
1585         int cpu, success = 0;
1586 
1587         /*
1588          * If we are going to wake up a thread waiting for CONDITION we
1589          * need to ensure that CONDITION=1 done by the caller can not be
1590          * reordered with p->state check below. This pairs with mb() in
1591          * set_current_state() the waiting thread does.
1592          */
1593         smp_mb__before_spinlock();
1594         raw_spin_lock_irqsave(&p->pi_lock, flags);
1595         if (!(p->state & state))
1596                 goto out;
1597 
1598         success = 1; /* we're going to change ->state */
1599         cpu = task_cpu(p);
1600 
1601         if (p->on_rq && ttwu_remote(p, wake_flags))
1602                 goto stat;
1603 
1604 #ifdef CONFIG_SMP
1605         /*
1606          * If the owning (remote) cpu is still in the middle of schedule() with
1607          * this task as prev, wait until its done referencing the task.
1608          */
1609         while (p->on_cpu)
1610                 cpu_relax();
1611         /*
1612          * Pairs with the smp_wmb() in finish_lock_switch().
1613          */
1614         smp_rmb();
1615 
1616         p->sched_contributes_to_load = !!task_contributes_to_load(p);
1617         p->state = TASK_WAKING;
1618 
1619         if (p->sched_class->task_waking)
1620                 p->sched_class->task_waking(p);
1621 
1622         cpu = select_task_rq(p, p->wake_cpu, SD_BALANCE_WAKE, wake_flags);
1623         if (task_cpu(p) != cpu) {
1624                 wake_flags |= WF_MIGRATED;
1625                 set_task_cpu(p, cpu);
1626         }
1627 #endif /* CONFIG_SMP */
1628 
1629         ttwu_queue(p, cpu);
1630 stat:
1631         ttwu_stat(p, cpu, wake_flags);
1632 out:
1633         raw_spin_unlock_irqrestore(&p->pi_lock, flags);
1634 
1635         return success;
1636 }
1637 
1638 /**
1639  * try_to_wake_up_local - try to wake up a local task with rq lock held
1640  * @p: the thread to be awakened
1641  *
1642  * Put @p on the run-queue if it's not already there. The caller must
1643  * ensure that this_rq() is locked, @p is bound to this_rq() and not
1644  * the current task.
1645  */
1646 static void try_to_wake_up_local(struct task_struct *p)
1647 {
1648         struct rq *rq = task_rq(p);
1649 
1650         if (WARN_ON_ONCE(rq != this_rq()) ||
1651             WARN_ON_ONCE(p == current))
1652                 return;
1653 
1654         lockdep_assert_held(&rq->lock);
1655 
1656         if (!raw_spin_trylock(&p->pi_lock)) {
1657                 raw_spin_unlock(&rq->lock);
1658                 raw_spin_lock(&p->pi_lock);
1659                 raw_spin_lock(&rq->lock);
1660         }
1661 
1662         if (!(p->state & TASK_NORMAL))
1663                 goto out;
1664 
1665         if (!p->on_rq)
1666                 ttwu_activate(rq, p, ENQUEUE_WAKEUP);
1667 
1668         ttwu_do_wakeup(rq, p, 0);
1669         ttwu_stat(p, smp_processor_id(), 0);
1670 out:
1671         raw_spin_unlock(&p->pi_lock);
1672 }
1673 
1674 /**
1675  * wake_up_process - Wake up a specific process
1676  * @p: The process to be woken up.
1677  *
1678  * Attempt to wake up the nominated process and move it to the set of runnable
1679  * processes.
1680  *
1681  * Return: 1 if the process was woken up, 0 if it was already running.
1682  *
1683  * It may be assumed that this function implies a write memory barrier before
1684  * changing the task state if and only if any tasks are woken up.
1685  */
1686 int wake_up_process(struct task_struct *p)
1687 {
1688         WARN_ON(task_is_stopped_or_traced(p));
1689         return try_to_wake_up(p, TASK_NORMAL, 0);
1690 }
1691 EXPORT_SYMBOL(wake_up_process);
1692 
1693 int wake_up_state(struct task_struct *p, unsigned int state)
1694 {
1695         return try_to_wake_up(p, state, 0);
1696 }
1697 
1698 /*
1699  * Perform scheduler related setup for a newly forked process p.
1700  * p is forked by current.
1701  *
1702  * __sched_fork() is basic setup used by init_idle() too:
1703  */
1704 static void __sched_fork(unsigned long clone_flags, struct task_struct *p)
1705 {
1706         p->on_rq                        = 0;
1707 
1708         p->se.on_rq                     = 0;
1709         p->se.exec_start                = 0;
1710         p->se.sum_exec_runtime          = 0;
1711         p->se.prev_sum_exec_runtime     = 0;
1712         p->se.nr_migrations             = 0;
1713         p->se.vruntime                  = 0;
1714         INIT_LIST_HEAD(&p->se.group_node);
1715 
1716 #ifdef CONFIG_SCHEDSTATS
1717         memset(&p->se.statistics, 0, sizeof(p->se.statistics));
1718 #endif
1719 
1720         INIT_LIST_HEAD(&p->rt.run_list);
1721 
1722 #ifdef CONFIG_PREEMPT_NOTIFIERS
1723         INIT_HLIST_HEAD(&p->preempt_notifiers);
1724 #endif
1725 
1726 #ifdef CONFIG_NUMA_BALANCING
1727         if (p->mm && atomic_read(&p->mm->mm_users) == 1) {
1728                 p->mm->numa_next_scan = jiffies + msecs_to_jiffies(sysctl_numa_balancing_scan_delay);
1729                 p->mm->numa_scan_seq = 0;
1730         }
1731 
1732         if (clone_flags & CLONE_VM)
1733                 p->numa_preferred_nid = current->numa_preferred_nid;
1734         else
1735                 p->numa_preferred_nid = -1;
1736 
1737         p->node_stamp = 0ULL;
1738         p->numa_scan_seq = p->mm ? p->mm->numa_scan_seq : 0;
1739         p->numa_scan_period = sysctl_numa_balancing_scan_delay;
1740         p->numa_work.next = &p->numa_work;
1741         p->numa_faults = NULL;
1742         p->numa_faults_buffer = NULL;
1743 
1744         INIT_LIST_HEAD(&p->numa_entry);
1745         p->numa_group = NULL;
1746 #endif /* CONFIG_NUMA_BALANCING */
1747 }
1748 
1749 #ifdef CONFIG_NUMA_BALANCING
1750 #ifdef CONFIG_SCHED_DEBUG
1751 void set_numabalancing_state(bool enabled)
1752 {
1753         if (enabled)
1754                 sched_feat_set("NUMA");
1755         else
1756                 sched_feat_set("NO_NUMA");
1757 }
1758 #else
1759 __read_mostly bool numabalancing_enabled;
1760 
1761 void set_numabalancing_state(bool enabled)
1762 {
1763         numabalancing_enabled = enabled;
1764 }
1765 #endif /* CONFIG_SCHED_DEBUG */
1766 #endif /* CONFIG_NUMA_BALANCING */
1767 
1768 /*
1769  * fork()/clone()-time setup:
1770  */
1771 void sched_fork(unsigned long clone_flags, struct task_struct *p)
1772 {
1773         unsigned long flags;
1774         int cpu = get_cpu();
1775 
1776         __sched_fork(clone_flags, p);
1777         /*
1778          * We mark the process as running here. This guarantees that
1779          * nobody will actually run it, and a signal or other external
1780          * event cannot wake it up and insert it on the runqueue either.
1781          */
1782         p->state = TASK_RUNNING;
1783 
1784         /*
1785          * Make sure we do not leak PI boosting priority to the child.
1786          */
1787         p->prio = current->normal_prio;
1788 
1789         /*
1790          * Revert to default priority/policy on fork if requested.
1791          */
1792         if (unlikely(p->sched_reset_on_fork)) {
1793                 if (task_has_rt_policy(p)) {
1794                         p->policy = SCHED_NORMAL;
1795                         p->static_prio = NICE_TO_PRIO(0);
1796                         p->rt_priority = 0;
1797                 } else if (PRIO_TO_NICE(p->static_prio) < 0)
1798                         p->static_prio = NICE_TO_PRIO(0);
1799 
1800                 p->prio = p->normal_prio = __normal_prio(p);
1801                 set_load_weight(p);
1802 
1803                 /*
1804                  * We don't need the reset flag anymore after the fork. It has
1805                  * fulfilled its duty:
1806                  */
1807                 p->sched_reset_on_fork = 0;
1808         }
1809 
1810         if (!rt_prio(p->prio))
1811                 p->sched_class = &fair_sched_class;
1812 
1813         if (p->sched_class->task_fork)
1814                 p->sched_class->task_fork(p);
1815 
1816         /*
1817          * The child is not yet in the pid-hash so no cgroup attach races,
1818          * and the cgroup is pinned to this child due to cgroup_fork()
1819          * is ran before sched_fork().
1820          *
1821          * Silence PROVE_RCU.
1822          */
1823         raw_spin_lock_irqsave(&p->pi_lock, flags);
1824         set_task_cpu(p, cpu);
1825         raw_spin_unlock_irqrestore(&p->pi_lock, flags);
1826 
1827 #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
1828         if (likely(sched_info_on()))
1829                 memset(&p->sched_info, 0, sizeof(p->sched_info));
1830 #endif
1831 #if defined(CONFIG_SMP)
1832         p->on_cpu = 0;
1833 #endif
1834         init_task_preempt_count(p);
1835 #ifdef CONFIG_SMP
1836         plist_node_init(&p->pushable_tasks, MAX_PRIO);
1837 #endif
1838 
1839         put_cpu();
1840 }
1841 
1842 /*
1843  * wake_up_new_task - wake up a newly created task for the first time.
1844  *
1845  * This function will do some initial scheduler statistics housekeeping
1846  * that must be done for every newly created context, then puts the task
1847  * on the runqueue and wakes it.
1848  */
1849 void wake_up_new_task(struct task_struct *p)
1850 {
1851         unsigned long flags;
1852         struct rq *rq;
1853 
1854         raw_spin_lock_irqsave(&p->pi_lock, flags);
1855 #ifdef CONFIG_SMP
1856         /*
1857          * Fork balancing, do it here and not earlier because:
1858          *  - cpus_allowed can change in the fork path
1859          *  - any previously selected cpu might disappear through hotplug
1860          */
1861         set_task_cpu(p, select_task_rq(p, task_cpu(p), SD_BALANCE_FORK, 0));
1862 #endif
1863 
1864         /* Initialize new task's runnable average */
1865         init_task_runnable_average(p);
1866         rq = __task_rq_lock(p);
1867         activate_task(rq, p, 0);
1868         p->on_rq = 1;
1869         trace_sched_wakeup_new(p, true);
1870         check_preempt_curr(rq, p, WF_FORK);
1871 #ifdef CONFIG_SMP
1872         if (p->sched_class->task_woken)
1873                 p->sched_class->task_woken(rq, p);
1874 #endif
1875         task_rq_unlock(rq, p, &flags);
1876 }
1877 
1878 #ifdef CONFIG_PREEMPT_NOTIFIERS
1879 
1880 /**
1881  * preempt_notifier_register - tell me when current is being preempted & rescheduled
1882  * @notifier: notifier struct to register
1883  */
1884 void preempt_notifier_register(struct preempt_notifier *notifier)
1885 {
1886         hlist_add_head(&notifier->link, &current->preempt_notifiers);
1887 }
1888 EXPORT_SYMBOL_GPL(preempt_notifier_register);
1889 
1890 /**
1891  * preempt_notifier_unregister - no longer interested in preemption notifications
1892  * @notifier: notifier struct to unregister
1893  *
1894  * This is safe to call from within a preemption notifier.
1895  */
1896 void preempt_notifier_unregister(struct preempt_notifier *notifier)
1897 {
1898         hlist_del(&notifier->link);
1899 }
1900 EXPORT_SYMBOL_GPL(preempt_notifier_unregister);
1901 
1902 static void fire_sched_in_preempt_notifiers(struct task_struct *curr)
1903 {
1904         struct preempt_notifier *notifier;
1905 
1906         hlist_for_each_entry(notifier, &curr->preempt_notifiers, link)
1907                 notifier->ops->sched_in(notifier, raw_smp_processor_id());
1908 }
1909 
1910 static void
1911 fire_sched_out_preempt_notifiers(struct task_struct *curr,
1912                                  struct task_struct *next)
1913 {
1914         struct preempt_notifier *notifier;
1915 
1916         hlist_for_each_entry(notifier, &curr->preempt_notifiers, link)
1917                 notifier->ops->sched_out(notifier, next);
1918 }
1919 
1920 #else /* !CONFIG_PREEMPT_NOTIFIERS */
1921 
1922 static void fire_sched_in_preempt_notifiers(struct task_struct *curr)
1923 {
1924 }
1925 
1926 static void
1927 fire_sched_out_preempt_notifiers(struct task_struct *curr,
1928                                  struct task_struct *next)
1929 {
1930 }
1931 
1932 #endif /* CONFIG_PREEMPT_NOTIFIERS */
1933 
1934 /**
1935  * prepare_task_switch - prepare to switch tasks
1936  * @rq: the runqueue preparing to switch
1937  * @prev: the current task that is being switched out
1938  * @next: the task we are going to switch to.
1939  *
1940  * This is called with the rq lock held and interrupts off. It must
1941  * be paired with a subsequent finish_task_switch after the context
1942  * switch.
1943  *
1944  * prepare_task_switch sets up locking and calls architecture specific
1945  * hooks.
1946  */
1947 static inline void
1948 prepare_task_switch(struct rq *rq, struct task_struct *prev,
1949                     struct task_struct *next)
1950 {
1951         trace_sched_switch(prev, next);
1952         sched_info_switch(rq, prev, next);
1953         perf_event_task_sched_out(prev, next);
1954         fire_sched_out_preempt_notifiers(prev, next);
1955         prepare_lock_switch(rq, next);
1956         prepare_arch_switch(next);
1957 }
1958 
1959 /**
1960  * finish_task_switch - clean up after a task-switch
1961  * @rq: runqueue associated with task-switch
1962  * @prev: the thread we just switched away from.
1963  *
1964  * finish_task_switch must be called after the context switch, paired
1965  * with a prepare_task_switch call before the context switch.
1966  * finish_task_switch will reconcile locking set up by prepare_task_switch,
1967  * and do any other architecture-specific cleanup actions.
1968  *
1969  * Note that we may have delayed dropping an mm in context_switch(). If
1970  * so, we finish that here outside of the runqueue lock. (Doing it
1971  * with the lock held can cause deadlocks; see schedule() for
1972  * details.)
1973  */
1974 static void finish_task_switch(struct rq *rq, struct task_struct *prev)
1975         __releases(rq->lock)
1976 {
1977         struct mm_struct *mm = rq->prev_mm;
1978         long prev_state;
1979 
1980         rq->prev_mm = NULL;
1981 
1982         /*
1983          * A task struct has one reference for the use as "current".
1984          * If a task dies, then it sets TASK_DEAD in tsk->state and calls
1985          * schedule one last time. The schedule call will never return, and
1986          * the scheduled task must drop that reference.
1987          * The test for TASK_DEAD must occur while the runqueue locks are
1988          * still held, otherwise prev could be scheduled on another cpu, die
1989          * there before we look at prev->state, and then the reference would
1990          * be dropped twice.
1991          *              Manfred Spraul <manfred@colorfullife.com>
1992          */
1993         prev_state = prev->state;
1994         vtime_task_switch(prev);
1995         finish_arch_switch(prev);
1996         perf_event_task_sched_in(prev, current);
1997         finish_lock_switch(rq, prev);
1998         finish_arch_post_lock_switch();
1999 
2000         fire_sched_in_preempt_notifiers(current);
2001         if (mm)
2002                 mmdrop(mm);
2003         if (unlikely(prev_state == TASK_DEAD)) {
2004                 task_numa_free(prev);
2005 
2006                 /*
2007                  * Remove function-return probe instances associated with this
2008                  * task and put them back on the free list.
2009                  */
2010                 kprobe_flush_task(prev);
2011                 put_task_struct(prev);
2012         }
2013 
2014         tick_nohz_task_switch(current);
2015 }
2016 
2017 #ifdef CONFIG_SMP
2018 
2019 /* assumes rq->lock is held */
2020 static inline void pre_schedule(struct rq *rq, struct task_struct *prev)
2021 {
2022         if (prev->sched_class->pre_schedule)
2023                 prev->sched_class->pre_schedule(rq, prev);
2024 }
2025 
2026 /* rq->lock is NOT held, but preemption is disabled */
2027 static inline void post_schedule(struct rq *rq)
2028 {
2029         if (rq->post_schedule) {
2030                 unsigned long flags;
2031 
2032                 raw_spin_lock_irqsave(&rq->lock, flags);
2033                 if (rq->curr->sched_class->post_schedule)
2034                         rq->curr->sched_class->post_schedule(rq);
2035                 raw_spin_unlock_irqrestore(&rq->lock, flags);
2036 
2037                 rq->post_schedule = 0;
2038         }
2039 }
2040 
2041 #else
2042 
2043 static inline void pre_schedule(struct rq *rq, struct task_struct *p)
2044 {
2045 }
2046 
2047 static inline void post_schedule(struct rq *rq)
2048 {
2049 }
2050 
2051 #endif
2052 
2053 /**
2054  * schedule_tail - first thing a freshly forked thread must call.
2055  * @prev: the thread we just switched away from.
2056  */
2057 asmlinkage void schedule_tail(struct task_struct *prev)
2058         __releases(rq->lock)
2059 {
2060         struct rq *rq = this_rq();
2061 
2062         finish_task_switch(rq, prev);
2063 
2064         /*
2065          * FIXME: do we need to worry about rq being invalidated by the
2066          * task_switch?
2067          */
2068         post_schedule(rq);
2069 
2070 #ifdef __ARCH_WANT_UNLOCKED_CTXSW
2071         /* In this case, finish_task_switch does not reenable preemption */
2072         preempt_enable();
2073 #endif
2074         if (current->set_child_tid)
2075                 put_user(task_pid_vnr(current), current->set_child_tid);
2076 }
2077 
2078 /*
2079  * context_switch - switch to the new MM and the new
2080  * thread's register state.
2081  */
2082 static inline void
2083 context_switch(struct rq *rq, struct task_struct *prev,
2084                struct task_struct *next)
2085 {
2086         struct mm_struct *mm, *oldmm;
2087 
2088         prepare_task_switch(rq, prev, next);
2089 
2090         mm = next->mm;
2091         oldmm = prev->active_mm;
2092         /*
2093          * For paravirt, this is coupled with an exit in switch_to to
2094          * combine the page table reload and the switch backend into
2095          * one hypercall.
2096          */
2097         arch_start_context_switch(prev);
2098 
2099         if (!mm) {
2100                 next->active_mm = oldmm;
2101                 atomic_inc(&oldmm->mm_count);
2102                 enter_lazy_tlb(oldmm, next);
2103         } else
2104                 switch_mm(oldmm, mm, next);
2105 
2106         if (!prev->mm) {
2107                 prev->active_mm = NULL;
2108                 rq->prev_mm = oldmm;
2109         }
2110         /*
2111          * Since the runqueue lock will be released by the next
2112          * task (which is an invalid locking op but in the case
2113          * of the scheduler it's an obvious special-case), so we
2114          * do an early lockdep release here:
2115          */
2116 #ifndef __ARCH_WANT_UNLOCKED_CTXSW
2117         spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
2118 #endif
2119 
2120         context_tracking_task_switch(prev, next);
2121         /* Here we just switch the register state and the stack. */
2122         switch_to(prev, next, prev);
2123 
2124         barrier();
2125         /*
2126          * this_rq must be evaluated again because prev may have moved
2127          * CPUs since it called schedule(), thus the 'rq' on its stack
2128          * frame will be invalid.
2129          */
2130         finish_task_switch(this_rq(), prev);
2131 }
2132 
2133 /*
2134  * nr_running and nr_context_switches:
2135  *
2136  * externally visible scheduler statistics: current number of runnable
2137  * threads, total number of context switches performed since bootup.
2138  */
2139 unsigned long nr_running(void)
2140 {
2141         unsigned long i, sum = 0;
2142 
2143         for_each_online_cpu(i)
2144                 sum += cpu_rq(i)->nr_running;
2145 
2146         return sum;
2147 }
2148 
2149 unsigned long long nr_context_switches(void)
2150 {
2151         int i;
2152         unsigned long long sum = 0;
2153 
2154         for_each_possible_cpu(i)
2155                 sum += cpu_rq(i)->nr_switches;
2156 
2157         return sum;
2158 }
2159 
2160 unsigned long nr_iowait(void)
2161 {
2162         unsigned long i, sum = 0;
2163 
2164         for_each_possible_cpu(i)
2165                 sum += atomic_read(&cpu_rq(i)->nr_iowait);
2166 
2167         return sum;
2168 }
2169 
2170 unsigned long nr_iowait_cpu(int cpu)
2171 {
2172         struct rq *this = cpu_rq(cpu);
2173         return atomic_read(&this->nr_iowait);
2174 }
2175 
2176 #ifdef CONFIG_SMP
2177 
2178 /*
2179  * sched_exec - execve() is a valuable balancing opportunity, because at
2180  * this point the task has the smallest effective memory and cache footprint.
2181  */
2182 void sched_exec(void)
2183 {
2184         struct task_struct *p = current;
2185         unsigned long flags;
2186         int dest_cpu;
2187 
2188         raw_spin_lock_irqsave(&p->pi_lock, flags);
2189         dest_cpu = p->sched_class->select_task_rq(p, task_cpu(p), SD_BALANCE_EXEC, 0);
2190         if (dest_cpu == smp_processor_id())
2191                 goto unlock;
2192 
2193         if (likely(cpu_active(dest_cpu))) {
2194                 struct migration_arg arg = { p, dest_cpu };
2195 
2196                 raw_spin_unlock_irqrestore(&p->pi_lock, flags);
2197                 stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg);
2198                 return;
2199         }
2200 unlock:
2201         raw_spin_unlock_irqrestore(&p->pi_lock, flags);
2202 }
2203 
2204 #endif
2205 
2206 DEFINE_PER_CPU(struct kernel_stat, kstat);
2207 DEFINE_PER_CPU(struct kernel_cpustat, kernel_cpustat);
2208 
2209 EXPORT_PER_CPU_SYMBOL(kstat);
2210 EXPORT_PER_CPU_SYMBOL(kernel_cpustat);
2211 
2212 /*
2213  * Return any ns on the sched_clock that have not yet been accounted in
2214  * @p in case that task is currently running.
2215  *
2216  * Called with task_rq_lock() held on @rq.
2217  */
2218 static u64 do_task_delta_exec(struct task_struct *p, struct rq *rq)
2219 {
2220         u64 ns = 0;
2221 
2222         if (task_current(rq, p)) {
2223                 update_rq_clock(rq);
2224                 ns = rq_clock_task(rq) - p->se.exec_start;
2225                 if ((s64)ns < 0)
2226                         ns = 0;
2227         }
2228 
2229         return ns;
2230 }
2231 
2232 unsigned long long task_delta_exec(struct task_struct *p)
2233 {
2234         unsigned long flags;
2235         struct rq *rq;
2236         u64 ns = 0;
2237 
2238         rq = task_rq_lock(p, &flags);
2239         ns = do_task_delta_exec(p, rq);
2240         task_rq_unlock(rq, p, &flags);
2241 
2242         return ns;
2243 }
2244 
2245 /*
2246  * Return accounted runtime for the task.
2247  * In case the task is currently running, return the runtime plus current's
2248  * pending runtime that have not been accounted yet.
2249  */
2250 unsigned long long task_sched_runtime(struct task_struct *p)
2251 {
2252         unsigned long flags;
2253         struct rq *rq;
2254         u64 ns = 0;
2255 
2256 #if defined(CONFIG_64BIT) && defined(CONFIG_SMP)
2257         /*
2258          * 64-bit doesn't need locks to atomically read a 64bit value.
2259          * So we have a optimization chance when the task's delta_exec is 0.
2260          * Reading ->on_cpu is racy, but this is ok.
2261          *
2262          * If we race with it leaving cpu, we'll take a lock. So we're correct.
2263          * If we race with it entering cpu, unaccounted time is 0. This is
2264          * indistinguishable from the read occurring a few cycles earlier.
2265          */
2266         if (!p->on_cpu)
2267                 return p->se.sum_exec_runtime;
2268 #endif
2269 
2270         rq = task_rq_lock(p, &flags);
2271         ns = p->se.sum_exec_runtime + do_task_delta_exec(p, rq);
2272         task_rq_unlock(rq, p, &flags);
2273 
2274         return ns;
2275 }
2276 
2277 /*
2278  * This function gets called by the timer code, with HZ frequency.
2279  * We call it with interrupts disabled.
2280  */
2281 void scheduler_tick(void)
2282 {
2283         int cpu = smp_processor_id();
2284         struct rq *rq = cpu_rq(cpu);
2285         struct task_struct *curr = rq->curr;
2286 
2287         sched_clock_tick();
2288 
2289         raw_spin_lock(&rq->lock);
2290         update_rq_clock(rq);
2291         curr->sched_class->task_tick(rq, curr, 0);
2292         update_cpu_load_active(rq);
2293         raw_spin_unlock(&rq->lock);
2294 
2295         perf_event_task_tick();
2296 
2297 #ifdef CONFIG_SMP
2298         rq->idle_balance = idle_cpu(cpu);
2299         trigger_load_balance(rq, cpu);
2300 #endif
2301         rq_last_tick_reset(rq);
2302 }
2303 
2304 #ifdef CONFIG_NO_HZ_FULL
2305 /**
2306  * scheduler_tick_max_deferment
2307  *
2308  * Keep at least one tick per second when a single
2309  * active task is running because the scheduler doesn't
2310  * yet completely support full dynticks environment.
2311  *
2312  * This makes sure that uptime, CFS vruntime, load
2313  * balancing, etc... continue to move forward, even
2314  * with a very low granularity.
2315  *
2316  * Return: Maximum deferment in nanoseconds.
2317  */
2318 u64 scheduler_tick_max_deferment(void)
2319 {
2320         struct rq *rq = this_rq();
2321         unsigned long next, now = ACCESS_ONCE(jiffies);
2322 
2323         next = rq->last_sched_tick + HZ;
2324 
2325         if (time_before_eq(next, now))
2326                 return 0;
2327 
2328         return jiffies_to_usecs(next - now) * NSEC_PER_USEC;
2329 }
2330 #endif
2331 
2332 notrace unsigned long get_parent_ip(unsigned long addr)
2333 {
2334         if (in_lock_functions(addr)) {
2335                 addr = CALLER_ADDR2;
2336                 if (in_lock_functions(addr))
2337                         addr = CALLER_ADDR3;
2338         }
2339         return addr;
2340 }
2341 
2342 #if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \
2343                                 defined(CONFIG_PREEMPT_TRACER))
2344 
2345 void __kprobes preempt_count_add(int val)
2346 {
2347 #ifdef CONFIG_DEBUG_PREEMPT
2348         /*
2349          * Underflow?
2350          */
2351         if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
2352                 return;
2353 #endif
2354         __preempt_count_add(val);
2355 #ifdef CONFIG_DEBUG_PREEMPT
2356         /*
2357          * Spinlock count overflowing soon?
2358          */
2359         DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >=
2360                                 PREEMPT_MASK - 10);
2361 #endif
2362         if (preempt_count() == val)
2363                 trace_preempt_off(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1));
2364 }
2365 EXPORT_SYMBOL(preempt_count_add);
2366 
2367 void __kprobes preempt_count_sub(int val)
2368 {
2369 #ifdef CONFIG_DEBUG_PREEMPT
2370         /*
2371          * Underflow?
2372          */
2373         if (DEBUG_LOCKS_WARN_ON(val > preempt_count()))
2374                 return;
2375         /*
2376          * Is the spinlock portion underflowing?
2377          */
2378         if (DEBUG_LOCKS_WARN_ON((val < PREEMPT_MASK) &&
2379                         !(preempt_count() & PREEMPT_MASK)))
2380                 return;
2381 #endif
2382 
2383         if (preempt_count() == val)
2384                 trace_preempt_on(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1));
2385         __preempt_count_sub(val);
2386 }
2387 EXPORT_SYMBOL(preempt_count_sub);
2388 
2389 #endif
2390 
2391 /*
2392  * Print scheduling while atomic bug:
2393  */
2394 static noinline void __schedule_bug(struct task_struct *prev)
2395 {
2396         if (oops_in_progress)
2397                 return;
2398 
2399         printk(KERN_ERR "BUG: scheduling while atomic: %s/%d/0x%08x\n",
2400                 prev->comm, prev->pid, preempt_count());
2401 
2402         debug_show_held_locks(prev);
2403         print_modules();
2404         if (irqs_disabled())
2405                 print_irqtrace_events(prev);
2406         dump_stack();
2407         add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
2408 }
2409 
2410 /*
2411  * Various schedule()-time debugging checks and statistics:
2412  */
2413 static inline void schedule_debug(struct task_struct *prev)
2414 {
2415         /*
2416          * Test if we are atomic. Since do_exit() needs to call into
2417          * schedule() atomically, we ignore that path for now.
2418          * Otherwise, whine if we are scheduling when we should not be.
2419          */
2420         if (unlikely(in_atomic_preempt_off() && !prev->exit_state))
2421                 __schedule_bug(prev);
2422         rcu_sleep_check();
2423 
2424         profile_hit(SCHED_PROFILING, __builtin_return_address(0));
2425 
2426         schedstat_inc(this_rq(), sched_count);
2427 }
2428 
2429 static void put_prev_task(struct rq *rq, struct task_struct *prev)
2430 {
2431         if (prev->on_rq || rq->skip_clock_update < 0)
2432                 update_rq_clock(rq);
2433         prev->sched_class->put_prev_task(rq, prev);
2434 }
2435 
2436 /*
2437  * Pick up the highest-prio task:
2438  */
2439 static inline struct task_struct *
2440 pick_next_task(struct rq *rq)
2441 {
2442         const struct sched_class *class;
2443         struct task_struct *p;
2444 
2445         /*
2446          * Optimization: we know that if all tasks are in
2447          * the fair class we can call that function directly:
2448          */
2449         if (likely(rq->nr_running == rq->cfs.h_nr_running)) {
2450                 p = fair_sched_class.pick_next_task(rq);
2451                 if (likely(p))
2452                         return p;
2453         }
2454 
2455         for_each_class(class) {
2456                 p = class->pick_next_task(rq);
2457                 if (p)
2458                         return p;
2459         }
2460 
2461         BUG(); /* the idle class will always have a runnable task */
2462 }
2463 
2464 /*
2465  * __schedule() is the main scheduler function.
2466  *
2467  * The main means of driving the scheduler and thus entering this function are:
2468  *
2469  *   1. Explicit blocking: mutex, semaphore, waitqueue, etc.
2470  *
2471  *   2. TIF_NEED_RESCHED flag is checked on interrupt and userspace return
2472  *      paths. For example, see arch/x86/entry_64.S.
2473  *
2474  *      To drive preemption between tasks, the scheduler sets the flag in timer
2475  *      interrupt handler scheduler_tick().
2476  *
2477  *   3. Wakeups don't really cause entry into schedule(). They add a
2478  *      task to the run-queue and that's it.
2479  *
2480  *      Now, if the new task added to the run-queue preempts the current
2481  *      task, then the wakeup sets TIF_NEED_RESCHED and schedule() gets
2482  *      called on the nearest possible occasion:
2483  *
2484  *       - If the kernel is preemptible (CONFIG_PREEMPT=y):
2485  *
2486  *         - in syscall or exception context, at the next outmost
2487  *           preempt_enable(). (this might be as soon as the wake_up()'s
2488  *           spin_unlock()!)
2489  *
2490  *         - in IRQ context, return from interrupt-handler to
2491  *           preemptible context
2492  *
2493  *       - If the kernel is not preemptible (CONFIG_PREEMPT is not set)
2494  *         then at the next:
2495  *
2496  *          - cond_resched() call
2497  *          - explicit schedule() call
2498  *          - return from syscall or exception to user-space
2499  *          - return from interrupt-handler to user-space
2500  */
2501 static void __sched __schedule(void)
2502 {
2503         struct task_struct *prev, *next;
2504         unsigned long *switch_count;
2505         struct rq *rq;
2506         int cpu;
2507 
2508 need_resched:
2509         preempt_disable();
2510         cpu = smp_processor_id();
2511         rq = cpu_rq(cpu);
2512         rcu_note_context_switch(cpu);
2513         prev = rq->curr;
2514 
2515         schedule_debug(prev);
2516 
2517         if (sched_feat(HRTICK))
2518                 hrtick_clear(rq);
2519 
2520         /*
2521          * Make sure that signal_pending_state()->signal_pending() below
2522          * can't be reordered with __set_current_state(TASK_INTERRUPTIBLE)
2523          * done by the caller to avoid the race with signal_wake_up().
2524          */
2525         smp_mb__before_spinlock();
2526         raw_spin_lock_irq(&rq->lock);
2527 
2528         switch_count = &prev->nivcsw;
2529         if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) {
2530                 if (unlikely(signal_pending_state(prev->state, prev))) {
2531                         prev->state = TASK_RUNNING;
2532                 } else {
2533                         deactivate_task(rq, prev, DEQUEUE_SLEEP);
2534                         prev->on_rq = 0;
2535 
2536                         /*
2537                          * If a worker went to sleep, notify and ask workqueue
2538                          * whether it wants to wake up a task to maintain
2539                          * concurrency.
2540                          */
2541                         if (prev->flags & PF_WQ_WORKER) {
2542                                 struct task_struct *to_wakeup;
2543 
2544                                 to_wakeup = wq_worker_sleeping(prev, cpu);
2545                                 if (to_wakeup)
2546                                         try_to_wake_up_local(to_wakeup);
2547                         }
2548                 }
2549                 switch_count = &prev->nvcsw;
2550         }
2551 
2552         pre_schedule(rq, prev);
2553 
2554         if (unlikely(!rq->nr_running))
2555                 idle_balance(cpu, rq);
2556 
2557         put_prev_task(rq, prev);
2558         next = pick_next_task(rq);
2559         clear_tsk_need_resched(prev);
2560         clear_preempt_need_resched();
2561         rq->skip_clock_update = 0;
2562 
2563         if (likely(prev != next)) {
2564                 rq->nr_switches++;
2565                 rq->curr = next;
2566                 ++*switch_count;
2567 
2568                 context_switch(rq, prev, next); /* unlocks the rq */
2569                 /*
2570                  * The context switch have flipped the stack from under us
2571                  * and restored the local variables which were saved when
2572                  * this task called schedule() in the past. prev == current
2573                  * is still correct, but it can be moved to another cpu/rq.
2574                  */
2575                 cpu = smp_processor_id();
2576                 rq = cpu_rq(cpu);
2577         } else
2578                 raw_spin_unlock_irq(&rq->lock);
2579 
2580         post_schedule(rq);
2581 
2582         sched_preempt_enable_no_resched();
2583         if (need_resched())
2584                 goto need_resched;
2585 }
2586 
2587 static inline void sched_submit_work(struct task_struct *tsk)
2588 {
2589         if (!tsk->state || tsk_is_pi_blocked(tsk))
2590                 return;
2591         /*
2592          * If we are going to sleep and we have plugged IO queued,
2593          * make sure to submit it to avoid deadlocks.
2594          */
2595         if (blk_needs_flush_plug(tsk))
2596                 blk_schedule_flush_plug(tsk);
2597 }
2598 
2599 asmlinkage void __sched schedule(void)
2600 {
2601         struct task_struct *tsk = current;
2602 
2603         sched_submit_work(tsk);
2604         __schedule();
2605 }
2606 EXPORT_SYMBOL(schedule);
2607 
2608 #ifdef CONFIG_CONTEXT_TRACKING
2609 asmlinkage void __sched schedule_user(void)
2610 {
2611         /*
2612          * If we come here after a random call to set_need_resched(),
2613          * or we have been woken up remotely but the IPI has not yet arrived,
2614          * we haven't yet exited the RCU idle mode. Do it here manually until
2615          * we find a better solution.
2616          */
2617         user_exit();
2618         schedule();
2619         user_enter();
2620 }
2621 #endif
2622 
2623 /**
2624  * schedule_preempt_disabled - called with preemption disabled
2625  *
2626  * Returns with preemption disabled. Note: preempt_count must be 1
2627  */
2628 void __sched schedule_preempt_disabled(void)
2629 {
2630         sched_preempt_enable_no_resched();
2631         schedule();
2632         preempt_disable();
2633 }
2634 
2635 #ifdef CONFIG_PREEMPT
2636 /*
2637  * this is the entry point to schedule() from in-kernel preemption
2638  * off of preempt_enable. Kernel preemptions off return from interrupt
2639  * occur there and call schedule directly.
2640  */
2641 asmlinkage void __sched notrace preempt_schedule(void)
2642 {
2643         /*
2644          * If there is a non-zero preempt_count or interrupts are disabled,
2645          * we do not want to preempt the current task. Just return..
2646          */
2647         if (likely(!preemptible()))
2648                 return;
2649 
2650         do {
2651                 __preempt_count_add(PREEMPT_ACTIVE);
2652                 __schedule();
2653                 __preempt_count_sub(PREEMPT_ACTIVE);
2654 
2655                 /*
2656                  * Check again in case we missed a preemption opportunity
2657                  * between schedule and now.
2658                  */
2659                 barrier();
2660         } while (need_resched());
2661 }
2662 EXPORT_SYMBOL(preempt_schedule);
2663 #endif /* CONFIG_PREEMPT */
2664 
2665 /*
2666  * this is the entry point to schedule() from kernel preemption
2667  * off of irq context.
2668  * Note, that this is called and return with irqs disabled. This will
2669  * protect us against recursive calling from irq.
2670  */
2671 asmlinkage void __sched preempt_schedule_irq(void)
2672 {
2673         enum ctx_state prev_state;
2674 
2675         /* Catch callers which need to be fixed */
2676         BUG_ON(preempt_count() || !irqs_disabled());
2677 
2678         prev_state = exception_enter();
2679 
2680         do {
2681                 __preempt_count_add(PREEMPT_ACTIVE);
2682                 local_irq_enable();
2683                 __schedule();
2684                 local_irq_disable();
2685                 __preempt_count_sub(PREEMPT_ACTIVE);
2686 
2687                 /*
2688                  * Check again in case we missed a preemption opportunity
2689                  * between schedule and now.
2690                  */
2691                 barrier();
2692         } while (need_resched());
2693 
2694         exception_exit(prev_state);
2695 }
2696 
2697 int default_wake_function(wait_queue_t *curr, unsigned mode, int wake_flags,
2698                           void *key)
2699 {
2700         return try_to_wake_up(curr->private, mode, wake_flags);
2701 }
2702 EXPORT_SYMBOL(default_wake_function);
2703 
2704 static long __sched
2705 sleep_on_common(wait_queue_head_t *q, int state, long timeout)
2706 {
2707         unsigned long flags;
2708         wait_queue_t wait;
2709 
2710         init_waitqueue_entry(&wait, current);
2711 
2712         __set_current_state(state);
2713 
2714         spin_lock_irqsave(&q->lock, flags);
2715         __add_wait_queue(q, &wait);
2716         spin_unlock(&q->lock);
2717         timeout = schedule_timeout(timeout);
2718         spin_lock_irq(&q->lock);
2719         __remove_wait_queue(q, &wait);
2720         spin_unlock_irqrestore(&q->lock, flags);
2721 
2722         return timeout;
2723 }
2724 
2725 void __sched interruptible_sleep_on(wait_queue_head_t *q)
2726 {
2727         sleep_on_common(q, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
2728 }
2729 EXPORT_SYMBOL(interruptible_sleep_on);
2730 
2731 long __sched
2732 interruptible_sleep_on_timeout(wait_queue_head_t *q, long timeout)
2733 {
2734         return sleep_on_common(q, TASK_INTERRUPTIBLE, timeout);
2735 }
2736 EXPORT_SYMBOL(interruptible_sleep_on_timeout);
2737 
2738 void __sched sleep_on(wait_queue_head_t *q)
2739 {
2740         sleep_on_common(q, TASK_UNINTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
2741 }
2742 EXPORT_SYMBOL(sleep_on);
2743 
2744 long __sched sleep_on_timeout(wait_queue_head_t *q, long timeout)
2745 {
2746         return sleep_on_common(q, TASK_UNINTERRUPTIBLE, timeout);
2747 }
2748 EXPORT_SYMBOL(sleep_on_timeout);
2749 
2750 #ifdef CONFIG_RT_MUTEXES
2751 
2752 /*
2753  * rt_mutex_setprio - set the current priority of a task
2754  * @p: task
2755  * @prio: prio value (kernel-internal form)
2756  *
2757  * This function changes the 'effective' priority of a task. It does
2758  * not touch ->normal_prio like __setscheduler().
2759  *
2760  * Used by the rt_mutex code to implement priority inheritance logic.
2761  */
2762 void rt_mutex_setprio(struct task_struct *p, int prio)
2763 {
2764         int oldprio, on_rq, running;
2765         struct rq *rq;
2766         const struct sched_class *prev_class;
2767 
2768         BUG_ON(prio < 0 || prio > MAX_PRIO);
2769 
2770         rq = __task_rq_lock(p);
2771 
2772         /*
2773          * Idle task boosting is a nono in general. There is one
2774          * exception, when PREEMPT_RT and NOHZ is active:
2775          *
2776          * The idle task calls get_next_timer_interrupt() and holds
2777          * the timer wheel base->lock on the CPU and another CPU wants
2778          * to access the timer (probably to cancel it). We can safely
2779          * ignore the boosting request, as the idle CPU runs this code
2780          * with interrupts disabled and will complete the lock
2781          * protected section without being interrupted. So there is no
2782          * real need to boost.
2783          */
2784         if (unlikely(p == rq->idle)) {
2785                 WARN_ON(p != rq->curr);
2786                 WARN_ON(p->pi_blocked_on);
2787                 goto out_unlock;
2788         }
2789 
2790         trace_sched_pi_setprio(p, prio);
2791         oldprio = p->prio;
2792         prev_class = p->sched_class;
2793         on_rq = p->on_rq;
2794         running = task_current(rq, p);
2795         if (on_rq)
2796                 dequeue_task(rq, p, 0);
2797         if (running)
2798                 p->sched_class->put_prev_task(rq, p);
2799 
2800         if (rt_prio(prio))
2801                 p->sched_class = &rt_sched_class;
2802         else
2803                 p->sched_class = &fair_sched_class;
2804 
2805         p->prio = prio;
2806 
2807         if (running)
2808                 p->sched_class->set_curr_task(rq);
2809         if (on_rq)
2810                 enqueue_task(rq, p, oldprio < prio ? ENQUEUE_HEAD : 0);
2811 
2812         check_class_changed(rq, p, prev_class, oldprio);
2813 out_unlock:
2814         __task_rq_unlock(rq);
2815 }
2816 #endif
2817 void set_user_nice(struct task_struct *p, long nice)
2818 {
2819         int old_prio, delta, on_rq;
2820         unsigned long flags;
2821         struct rq *rq;
2822 
2823         if (TASK_NICE(p) == nice || nice < -20 || nice > 19)
2824                 return;
2825         /*
2826          * We have to be careful, if called from sys_setpriority(),
2827          * the task might be in the middle of scheduling on another CPU.
2828          */
2829         rq = task_rq_lock(p, &flags);
2830         /*
2831          * The RT priorities are set via sched_setscheduler(), but we still
2832          * allow the 'normal' nice value to be set - but as expected
2833          * it wont have any effect on scheduling until the task is
2834          * SCHED_FIFO/SCHED_RR:
2835          */
2836         if (task_has_rt_policy(p)) {
2837                 p->static_prio = NICE_TO_PRIO(nice);
2838                 goto out_unlock;
2839         }
2840         on_rq = p->on_rq;
2841         if (on_rq)
2842                 dequeue_task(rq, p, 0);
2843 
2844         p->static_prio = NICE_TO_PRIO(nice);
2845         set_load_weight(p);
2846         old_prio = p->prio;
2847         p->prio = effective_prio(p);
2848         delta = p->prio - old_prio;
2849 
2850         if (on_rq) {
2851                 enqueue_task(rq, p, 0);
2852                 /*
2853                  * If the task increased its priority or is running and
2854                  * lowered its priority, then reschedule its CPU:
2855                  */
2856                 if (delta < 0 || (delta > 0 && task_running(rq, p)))
2857                         resched_task(rq->curr);
2858         }
2859 out_unlock:
2860         task_rq_unlock(rq, p, &flags);
2861 }
2862 EXPORT_SYMBOL(set_user_nice);
2863 
2864 /*
2865  * can_nice - check if a task can reduce its nice value
2866  * @p: task
2867  * @nice: nice value
2868  */
2869 int can_nice(const struct task_struct *p, const int nice)
2870 {
2871         /* convert nice value [19,-20] to rlimit style value [1,40] */
2872         int nice_rlim = 20 - nice;
2873 
2874         return (nice_rlim <= task_rlimit(p, RLIMIT_NICE) ||
2875                 capable(CAP_SYS_NICE));
2876 }
2877 
2878 #ifdef __ARCH_WANT_SYS_NICE
2879 
2880 /*
2881  * sys_nice - change the priority of the current process.
2882  * @increment: priority increment
2883  *
2884  * sys_setpriority is a more generic, but much slower function that
2885  * does similar things.
2886  */
2887 SYSCALL_DEFINE1(nice, int, increment)
2888 {
2889         long nice, retval;
2890 
2891         /*
2892          * Setpriority might change our priority at the same moment.
2893          * We don't have to worry. Conceptually one call occurs first
2894          * and we have a single winner.
2895          */
2896         if (increment < -40)
2897                 increment = -40;
2898         if (increment > 40)
2899                 increment = 40;
2900 
2901         nice = TASK_NICE(current) + increment;
2902         if (nice < -20)
2903                 nice = -20;
2904         if (nice > 19)
2905                 nice = 19;
2906 
2907         if (increment < 0 && !can_nice(current, nice))
2908                 return -EPERM;
2909 
2910         retval = security_task_setnice(current, nice);
2911         if (retval)
2912                 return retval;
2913 
2914         set_user_nice(current, nice);
2915         return 0;
2916 }
2917 
2918 #endif
2919 
2920 /**
2921  * task_prio - return the priority value of a given task.
2922  * @p: the task in question.
2923  *
2924  * Return: The priority value as seen by users in /proc.
2925  * RT tasks are offset by -200. Normal tasks are centered
2926  * around 0, value goes from -16 to +15.
2927  */
2928 int task_prio(const struct task_struct *p)
2929 {
2930         return p->prio - MAX_RT_PRIO;
2931 }
2932 
2933 /**
2934  * task_nice - return the nice value of a given task.
2935  * @p: the task in question.
2936  *
2937  * Return: The nice value [ -20 ... 0 ... 19 ].
2938  */
2939 int task_nice(const struct task_struct *p)
2940 {
2941         return TASK_NICE(p);
2942 }
2943 EXPORT_SYMBOL(task_nice);
2944 
2945 /**
2946  * idle_cpu - is a given cpu idle currently?
2947  * @cpu: the processor in question.
2948  *
2949  * Return: 1 if the CPU is currently idle. 0 otherwise.
2950  */
2951 int idle_cpu(int cpu)
2952 {
2953         struct rq *rq = cpu_rq(cpu);
2954 
2955         if (rq->curr != rq->idle)
2956                 return 0;
2957 
2958         if (rq->nr_running)
2959                 return 0;
2960 
2961 #ifdef CONFIG_SMP
2962         if (!llist_empty(&rq->wake_list))
2963                 return 0;
2964 #endif
2965 
2966         return 1;
2967 }
2968 
2969 /**
2970  * idle_task - return the idle task for a given cpu.
2971  * @cpu: the processor in question.
2972  *
2973  * Return: The idle task for the cpu @cpu.
2974  */
2975 struct task_struct *idle_task(int cpu)
2976 {
2977         return cpu_rq(cpu)->idle;
2978 }
2979 
2980 /**
2981  * find_process_by_pid - find a process with a matching PID value.
2982  * @pid: the pid in question.
2983  *
2984  * The task of @pid, if found. %NULL otherwise.
2985  */
2986 static struct task_struct *find_process_by_pid(pid_t pid)
2987 {
2988         return pid ? find_task_by_vpid(pid) : current;
2989 }
2990 
2991 /* Actually do priority change: must hold rq lock. */
2992 static void
2993 __setscheduler(struct rq *rq, struct task_struct *p, int policy, int prio)
2994 {
2995         p->policy = policy;
2996         p->rt_priority = prio;
2997         p->normal_prio = normal_prio(p);
2998         /* we are holding p->pi_lock already */
2999         p->prio = rt_mutex_getprio(p);
3000         if (rt_prio(p->prio))
3001                 p->sched_class = &rt_sched_class;
3002         else
3003                 p->sched_class = &fair_sched_class;
3004         set_load_weight(p);
3005 }
3006 
3007 /*
3008  * check the target process has a UID that matches the current process's
3009  */
3010 static bool check_same_owner(struct task_struct *p)
3011 {
3012         const struct cred *cred = current_cred(), *pcred;
3013         bool match;
3014 
3015         rcu_read_lock();
3016         pcred = __task_cred(p);
3017         match = (uid_eq(cred->euid, pcred->euid) ||
3018                  uid_eq(cred->euid, pcred->uid));
3019         rcu_read_unlock();
3020         return match;
3021 }
3022 
3023 static int __sched_setscheduler(struct task_struct *p, int policy,
3024                                 const struct sched_param *param, bool user)
3025 {
3026         int retval, oldprio, oldpolicy = -1, on_rq, running;
3027         unsigned long flags;
3028         const struct sched_class *prev_class;
3029         struct rq *rq;
3030         int reset_on_fork;
3031 
3032         /* may grab non-irq protected spin_locks */
3033         BUG_ON(in_interrupt());
3034 recheck:
3035         /* double check policy once rq lock held */
3036         if (policy < 0) {
3037                 reset_on_fork = p->sched_reset_on_fork;
3038                 policy = oldpolicy = p->policy;
3039         } else {
3040                 reset_on_fork = !!(policy & SCHED_RESET_ON_FORK);
3041                 policy &= ~SCHED_RESET_ON_FORK;
3042 
3043                 if (policy != SCHED_FIFO && policy != SCHED_RR &&
3044                                 policy != SCHED_NORMAL && policy != SCHED_BATCH &&
3045                                 policy != SCHED_IDLE)
3046                         return -EINVAL;
3047         }
3048 
3049         /*
3050          * Valid priorities for SCHED_FIFO and SCHED_RR are
3051          * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL,
3052          * SCHED_BATCH and SCHED_IDLE is 0.
3053          */
3054         if (param->sched_priority < 0 ||
3055             (p->mm && param->sched_priority > MAX_USER_RT_PRIO-1) ||
3056             (!p->mm && param->sched_priority > MAX_RT_PRIO-1))
3057                 return -EINVAL;
3058         if (rt_policy(policy) != (param->sched_priority != 0))
3059                 return -EINVAL;
3060 
3061         /*
3062          * Allow unprivileged RT tasks to decrease priority:
3063          */
3064         if (user && !capable(CAP_SYS_NICE)) {
3065                 if (rt_policy(policy)) {
3066                         unsigned long rlim_rtprio =
3067                                         task_rlimit(p, RLIMIT_RTPRIO);
3068 
3069                         /* can't set/change the rt policy */
3070                         if (policy != p->policy && !rlim_rtprio)
3071                                 return -EPERM;
3072 
3073                         /* can't increase priority */
3074                         if (param->sched_priority > p->rt_priority &&
3075                             param->sched_priority > rlim_rtprio)
3076                                 return -EPERM;
3077                 }
3078 
3079                 /*
3080                  * Treat SCHED_IDLE as nice 20. Only allow a switch to
3081                  * SCHED_NORMAL if the RLIMIT_NICE would normally permit it.
3082                  */
3083                 if (p->policy == SCHED_IDLE && policy != SCHED_IDLE) {
3084                         if (!can_nice(p, TASK_NICE(p)))
3085                                 return -EPERM;
3086                 }
3087 
3088                 /* can't change other user's priorities */
3089                 if (!check_same_owner(p))
3090                         return -EPERM;
3091 
3092                 /* Normal users shall not reset the sched_reset_on_fork flag */
3093                 if (p->sched_reset_on_fork && !reset_on_fork)
3094                         return -EPERM;
3095         }
3096 
3097         if (user) {
3098                 retval = security_task_setscheduler(p);
3099                 if (retval)
3100                         return retval;
3101         }
3102 
3103         /*
3104          * make sure no PI-waiters arrive (or leave) while we are
3105          * changing the priority of the task:
3106          *
3107          * To be able to change p->policy safely, the appropriate
3108          * runqueue lock must be held.
3109          */
3110         rq = task_rq_lock(p, &flags);
3111 
3112         /*
3113          * Changing the policy of the stop threads its a very bad idea
3114          */
3115         if (p == rq->stop) {
3116                 task_rq_unlock(rq, p, &flags);
3117                 return -EINVAL;
3118         }
3119 
3120         /*
3121          * If not changing anything there's no need to proceed further:
3122          */
3123         if (unlikely(policy == p->policy && (!rt_policy(policy) ||
3124                         param->sched_priority == p->rt_priority))) {
3125                 task_rq_unlock(rq, p, &flags);
3126                 return 0;
3127         }
3128 
3129 #ifdef CONFIG_RT_GROUP_SCHED
3130         if (user) {
3131                 /*
3132                  * Do not allow realtime tasks into groups that have no runtime
3133                  * assigned.
3134                  */
3135                 if (rt_bandwidth_enabled() && rt_policy(policy) &&
3136                                 task_group(p)->rt_bandwidth.rt_runtime == 0 &&
3137                                 !task_group_is_autogroup(task_group(p))) {
3138                         task_rq_unlock(rq, p, &flags);
3139                         return -EPERM;
3140                 }
3141         }
3142 #endif
3143 
3144         /* recheck policy now with rq lock held */
3145         if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) {
3146                 policy = oldpolicy = -1;
3147                 task_rq_unlock(rq, p, &flags);
3148                 goto recheck;
3149         }
3150         on_rq = p->on_rq;
3151         running = task_current(rq, p);
3152         if (on_rq)
3153                 dequeue_task(rq, p, 0);
3154         if (running)
3155                 p->sched_class->put_prev_task(rq, p);
3156 
3157         p->sched_reset_on_fork = reset_on_fork;
3158 
3159         oldprio = p->prio;
3160         prev_class = p->sched_class;
3161         __setscheduler(rq, p, policy, param->sched_priority);
3162 
3163         if (running)
3164                 p->sched_class->set_curr_task(rq);
3165         if (on_rq)
3166                 enqueue_task(rq, p, 0);
3167 
3168         check_class_changed(rq, p, prev_class, oldprio);
3169         task_rq_unlock(rq, p, &flags);
3170 
3171         rt_mutex_adjust_pi(p);
3172 
3173         return 0;
3174 }
3175 
3176 /**
3177  * sched_setscheduler - change the scheduling policy and/or RT priority of a thread.
3178  * @p: the task in question.
3179  * @policy: new policy.
3180  * @param: structure containing the new RT priority.
3181  *
3182  * Return: 0 on success. An error code otherwise.
3183  *
3184  * NOTE that the task may be already dead.
3185  */
3186 int sched_setscheduler(struct task_struct *p, int policy,
3187                        const struct sched_param *param)
3188 {
3189         return __sched_setscheduler(p, policy, param, true);
3190 }
3191 EXPORT_SYMBOL_GPL(sched_setscheduler);
3192 
3193 /**
3194  * sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace.
3195  * @p: the task in question.
3196  * @policy: new policy.
3197  * @param: structure containing the new RT priority.
3198  *
3199  * Just like sched_setscheduler, only don't bother checking if the
3200  * current context has permission.  For example, this is needed in
3201  * stop_machine(): we create temporary high priority worker threads,
3202  * but our caller might not have that capability.
3203  *
3204  * Return: 0 on success. An error code otherwise.
3205  */
3206 int sched_setscheduler_nocheck(struct task_struct *p, int policy,
3207                                const struct sched_param *param)
3208 {
3209         return __sched_setscheduler(p, policy, param, false);
3210 }
3211 
3212 static int
3213 do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param)
3214 {
3215         struct sched_param lparam;
3216         struct task_struct *p;
3217         int retval;
3218 
3219         if (!param || pid < 0)
3220                 return -EINVAL;
3221         if (copy_from_user(&lparam, param, sizeof(struct sched_param)))
3222                 return -EFAULT;
3223 
3224         rcu_read_lock();
3225         retval = -ESRCH;
3226         p = find_process_by_pid(pid);
3227         if (p != NULL)
3228                 retval = sched_setscheduler(p, policy, &lparam);
3229         rcu_read_unlock();
3230 
3231         return retval;
3232 }
3233 
3234 /**
3235  * sys_sched_setscheduler - set/change the scheduler policy and RT priority
3236  * @pid: the pid in question.
3237  * @policy: new policy.
3238  * @param: structure containing the new RT priority.
3239  *
3240  * Return: 0 on success. An error code otherwise.
3241  */
3242 SYSCALL_DEFINE3(sched_setscheduler, pid_t, pid, int, policy,
3243                 struct sched_param __user *, param)
3244 {
3245         /* negative values for policy are not valid */
3246         if (policy < 0)
3247                 return -EINVAL;
3248 
3249         return do_sched_setscheduler(pid, policy, param);
3250 }
3251 
3252 /**
3253  * sys_sched_setparam - set/change the RT priority of a thread
3254  * @pid: the pid in question.
3255  * @param: structure containing the new RT priority.
3256  *
3257  * Return: 0 on success. An error code otherwise.
3258  */
3259 SYSCALL_DEFINE2(sched_setparam, pid_t, pid, struct sched_param __user *, param)
3260 {
3261         return do_sched_setscheduler(pid, -1, param);
3262 }
3263 
3264 /**
3265  * sys_sched_getscheduler - get the policy (scheduling class) of a thread
3266  * @pid: the pid in question.
3267  *
3268  * Return: On success, the policy of the thread. Otherwise, a negative error
3269  * code.
3270  */
3271 SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid)
3272 {
3273         struct task_struct *p;
3274         int retval;
3275 
3276         if (pid < 0)
3277                 return -EINVAL;
3278 
3279         retval = -ESRCH;
3280         rcu_read_lock();
3281         p = find_process_by_pid(pid);
3282         if (p) {
3283                 retval = security_task_getscheduler(p);
3284                 if (!retval)
3285                         retval = p->policy
3286                                 | (p->sched_reset_on_fork ? SCHED_RESET_ON_FORK : 0);
3287         }
3288         rcu_read_unlock();
3289         return retval;
3290 }
3291 
3292 /**
3293  * sys_sched_getparam - get the RT priority of a thread
3294  * @pid: the pid in question.
3295  * @param: structure containing the RT priority.
3296  *
3297  * Return: On success, 0 and the RT priority is in @param. Otherwise, an error
3298  * code.
3299  */
3300 SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param)
3301 {
3302         struct sched_param lp;
3303         struct task_struct *p;
3304         int retval;
3305 
3306         if (!param || pid < 0)
3307                 return -EINVAL;
3308 
3309         rcu_read_lock();
3310         p = find_process_by_pid(pid);
3311         retval = -ESRCH;
3312         if (!p)
3313                 goto out_unlock;
3314 
3315         retval = security_task_getscheduler(p);
3316         if (retval)
3317                 goto out_unlock;
3318 
3319         lp.sched_priority = p->rt_priority;
3320         rcu_read_unlock();
3321 
3322         /*
3323          * This one might sleep, we cannot do it with a spinlock held ...
3324          */
3325         retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0;
3326 
3327         return retval;
3328 
3329 out_unlock:
3330         rcu_read_unlock();
3331         return retval;
3332 }
3333 
3334 long sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
3335 {
3336         cpumask_var_t cpus_allowed, new_mask;
3337         struct task_struct *p;
3338         int retval;
3339 
3340         rcu_read_lock();
3341 
3342         p = find_process_by_pid(pid);
3343         if (!p) {
3344                 rcu_read_unlock();
3345                 return -ESRCH;
3346         }
3347 
3348         /* Prevent p going away */
3349         get_task_struct(p);
3350         rcu_read_unlock();
3351 
3352         if (p->flags & PF_NO_SETAFFINITY) {
3353                 retval = -EINVAL;
3354                 goto out_put_task;
3355         }
3356         if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) {
3357                 retval = -ENOMEM;
3358                 goto out_put_task;
3359         }
3360         if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) {
3361                 retval = -ENOMEM;
3362                 goto out_free_cpus_allowed;
3363         }
3364         retval = -EPERM;
3365         if (!check_same_owner(p)) {
3366                 rcu_read_lock();
3367                 if (!ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE)) {
3368                         rcu_read_unlock();
3369                         goto out_unlock;
3370                 }
3371                 rcu_read_unlock();
3372         }
3373 
3374         retval = security_task_setscheduler(p);
3375         if (retval)
3376                 goto out_unlock;
3377 
3378         cpuset_cpus_allowed(p, cpus_allowed);
3379         cpumask_and(new_mask, in_mask, cpus_allowed);
3380 again:
3381         retval = set_cpus_allowed_ptr(p, new_mask);
3382 
3383         if (!retval) {
3384                 cpuset_cpus_allowed(p, cpus_allowed);
3385                 if (!cpumask_subset(new_mask, cpus_allowed)) {
3386                         /*
3387                          * We must have raced with a concurrent cpuset
3388                          * update. Just reset the cpus_allowed to the
3389                          * cpuset's cpus_allowed
3390                          */
3391                         cpumask_copy(new_mask, cpus_allowed);
3392                         goto again;
3393                 }
3394         }
3395 out_unlock:
3396         free_cpumask_var(new_mask);
3397 out_free_cpus_allowed:
3398         free_cpumask_var(cpus_allowed);
3399 out_put_task:
3400         put_task_struct(p);
3401         return retval;
3402 }
3403 
3404 static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len,
3405                              struct cpumask *new_mask)
3406 {
3407         if (len < cpumask_size())
3408                 cpumask_clear(new_mask);
3409         else if (len > cpumask_size())
3410                 len = cpumask_size();
3411 
3412         return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0;
3413 }
3414 
3415 /**
3416  * sys_sched_setaffinity - set the cpu affinity of a process
3417  * @pid: pid of the process
3418  * @len: length in bytes of the bitmask pointed to by user_mask_ptr
3419  * @user_mask_ptr: user-space pointer to the new cpu mask
3420  *
3421  * Return: 0 on success. An error code otherwise.
3422  */
3423 SYSCALL_DEFINE3(sched_setaffinity, pid_t, pid, unsigned int, len,
3424                 unsigned long __user *, user_mask_ptr)
3425 {
3426         cpumask_var_t new_mask;
3427         int retval;
3428 
3429         if (!alloc_cpumask_var(&new_mask, GFP_KERNEL))
3430                 return -ENOMEM;
3431 
3432         retval = get_user_cpu_mask(user_mask_ptr, len, new_mask);
3433         if (retval == 0)
3434                 retval = sched_setaffinity(pid, new_mask);
3435         free_cpumask_var(new_mask);
3436         return retval;
3437 }
3438 
3439 long sched_getaffinity(pid_t pid, struct cpumask *mask)
3440 {
3441         struct task_struct *p;
3442         unsigned long flags;
3443         int retval;
3444 
3445         rcu_read_lock();
3446 
3447         retval = -ESRCH;
3448         p = find_process_by_pid(pid);
3449         if (!p)
3450                 goto out_unlock;
3451 
3452         retval = security_task_getscheduler(p);
3453         if (retval)
3454                 goto out_unlock;
3455 
3456         raw_spin_lock_irqsave(&p->pi_lock, flags);
3457         cpumask_and(mask, &p->cpus_allowed, cpu_active_mask);
3458         raw_spin_unlock_irqrestore(&p->pi_lock, flags);
3459 
3460 out_unlock:
3461         rcu_read_unlock();
3462 
3463         return retval;
3464 }
3465 
3466 /**
3467  * sys_sched_getaffinity - get the cpu affinity of a process
3468  * @pid: pid of the process
3469  * @len: length in bytes of the bitmask pointed to by user_mask_ptr
3470  * @user_mask_ptr: user-space pointer to hold the current cpu mask
3471  *
3472  * Return: 0 on success. An error code otherwise.
3473  */
3474 SYSCALL_DEFINE3(sched_getaffinity, pid_t, pid, unsigned int, len,
3475                 unsigned long __user *, user_mask_ptr)
3476 {
3477         int ret;
3478         cpumask_var_t mask;
3479 
3480         if ((len * BITS_PER_BYTE) < nr_cpu_ids)
3481                 return -EINVAL;
3482         if (len & (sizeof(unsigned long)-1))
3483                 return -EINVAL;
3484 
3485         if (!alloc_cpumask_var(&mask, GFP_KERNEL))
3486                 return -ENOMEM;
3487 
3488         ret = sched_getaffinity(pid, mask);
3489         if (ret == 0) {
3490                 size_t retlen = min_t(size_t, len, cpumask_size());
3491 
3492                 if (copy_to_user(user_mask_ptr, mask, retlen))
3493                         ret = -EFAULT;
3494                 else
3495                         ret = retlen;
3496         }
3497         free_cpumask_var(mask);
3498 
3499         return ret;
3500 }
3501 
3502 /**
3503  * sys_sched_yield - yield the current processor to other threads.
3504  *
3505  * This function yields the current CPU to other tasks. If there are no
3506  * other threads running on this CPU then this function will return.
3507  *
3508  * Return: 0.
3509  */
3510 SYSCALL_DEFINE0(sched_yield)
3511 {
3512         struct rq *rq = this_rq_lock();
3513 
3514         schedstat_inc(rq, yld_count);
3515         current->sched_class->yield_task(rq);
3516 
3517         /*
3518          * Since we are going to call schedule() anyway, there's
3519          * no need to preempt or enable interrupts:
3520          */
3521         __release(rq->lock);
3522         spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
3523         do_raw_spin_unlock(&rq->lock);
3524         sched_preempt_enable_no_resched();
3525 
3526         schedule();
3527 
3528         return 0;
3529 }
3530 
3531 static void __cond_resched(void)
3532 {
3533         __preempt_count_add(PREEMPT_ACTIVE);
3534         __schedule();
3535         __preempt_count_sub(PREEMPT_ACTIVE);
3536 }
3537 
3538 int __sched _cond_resched(void)
3539 {
3540         if (should_resched()) {
3541                 __cond_resched();
3542                 return 1;
3543         }
3544         return 0;
3545 }
3546 EXPORT_SYMBOL(_cond_resched);
3547 
3548 /*
3549  * __cond_resched_lock() - if a reschedule is pending, drop the given lock,
3550  * call schedule, and on return reacquire the lock.
3551  *
3552  * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
3553  * operations here to prevent schedule() from being called twice (once via
3554  * spin_unlock(), once by hand).
3555  */
3556 int __cond_resched_lock(spinlock_t *lock)
3557 {
3558         int resched = should_resched();
3559         int ret = 0;
3560 
3561         lockdep_assert_held(lock);
3562 
3563         if (spin_needbreak(lock) || resched) {
3564                 spin_unlock(lock);
3565                 if (resched)
3566                         __cond_resched();
3567                 else
3568                         cpu_relax();
3569                 ret = 1;
3570                 spin_lock(lock);
3571         }
3572         return ret;
3573 }
3574 EXPORT_SYMBOL(__cond_resched_lock);
3575 
3576 int __sched __cond_resched_softirq(void)
3577 {
3578         BUG_ON(!in_softirq());
3579 
3580         if (should_resched()) {
3581                 local_bh_enable();
3582                 __cond_resched();
3583                 local_bh_disable();
3584                 return 1;
3585         }
3586         return 0;
3587 }
3588 EXPORT_SYMBOL(__cond_resched_softirq);
3589 
3590 /**
3591  * yield - yield the current processor to other threads.
3592  *
3593  * Do not ever use this function, there's a 99% chance you're doing it wrong.
3594  *
3595  * The scheduler is at all times free to pick the calling task as the most
3596  * eligible task to run, if removing the yield() call from your code breaks
3597  * it, its already broken.
3598  *
3599  * Typical broken usage is:
3600  *
3601  * while (!event)
3602  *      yield();
3603  *
3604  * where one assumes that yield() will let 'the other' process run that will
3605  * make event true. If the current task is a SCHED_FIFO task that will never
3606  * happen. Never use yield() as a progress guarantee!!
3607  *
3608  * If you want to use yield() to wait for something, use wait_event().
3609  * If you want to use yield() to be 'nice' for others, use cond_resched().
3610  * If you still want to use yield(), do not!
3611  */
3612 void __sched yield(void)
3613 {
3614         set_current_state(TASK_RUNNING);
3615         sys_sched_yield();
3616 }
3617 EXPORT_SYMBOL(yield);
3618 
3619 /**
3620  * yield_to - yield the current processor to another thread in
3621  * your thread group, or accelerate that thread toward the
3622  * processor it's on.
3623  * @p: target task
3624  * @preempt: whether task preemption is allowed or not
3625  *
3626  * It's the caller's job to ensure that the target task struct
3627  * can't go away on us before we can do any checks.
3628  *
3629  * Return:
3630  *      true (>0) if we indeed boosted the target task.
3631  *      false (0) if we failed to boost the target.
3632  *      -ESRCH if there's no task to yield to.
3633  */
3634 bool __sched yield_to(struct task_struct *p, bool preempt)
3635 {
3636         struct task_struct *curr = current;
3637         struct rq *rq, *p_rq;
3638         unsigned long flags;
3639         int yielded = 0;
3640 
3641         local_irq_save(flags);
3642         rq = this_rq();
3643 
3644 again:
3645         p_rq = task_rq(p);
3646         /*
3647          * If we're the only runnable task on the rq and target rq also
3648          * has only one task, there's absolutely no point in yielding.
3649          */
3650         if (rq->nr_running == 1 && p_rq->nr_running == 1) {
3651                 yielded = -ESRCH;
3652                 goto out_irq;
3653         }
3654 
3655         double_rq_lock(rq, p_rq);
3656         while (task_rq(p) != p_rq) {
3657                 double_rq_unlock(rq, p_rq);
3658                 goto again;
3659         }
3660 
3661         if (!curr->sched_class->yield_to_task)
3662                 goto out_unlock;
3663 
3664         if (curr->sched_class != p->sched_class)
3665                 goto out_unlock;
3666 
3667         if (task_running(p_rq, p) || p->state)
3668                 goto out_unlock;
3669 
3670         yielded = curr->sched_class->yield_to_task(rq, p, preempt);
3671         if (yielded) {
3672                 schedstat_inc(rq, yld_count);
3673                 /*
3674                  * Make p's CPU reschedule; pick_next_entity takes care of
3675                  * fairness.
3676                  */
3677                 if (preempt && rq != p_rq)
3678                         resched_task(p_rq->curr);
3679         }
3680 
3681 out_unlock:
3682         double_rq_unlock(rq, p_rq);
3683 out_irq:
3684         local_irq_restore(flags);
3685 
3686         if (yielded > 0)
3687                 schedule();
3688 
3689         return yielded;
3690 }
3691 EXPORT_SYMBOL_GPL(yield_to);
3692 
3693 /*
3694  * This task is about to go to sleep on IO. Increment rq->nr_iowait so
3695  * that process accounting knows that this is a task in IO wait state.
3696  */
3697 void __sched io_schedule(void)
3698 {
3699         struct rq *rq = raw_rq();
3700 
3701         delayacct_blkio_start();
3702         atomic_inc(&rq->nr_iowait);
3703         blk_flush_plug(current);
3704         current->in_iowait = 1;
3705         schedule();
3706         current->in_iowait = 0;
3707         atomic_dec(&rq->nr_iowait);
3708         delayacct_blkio_end();
3709 }
3710 EXPORT_SYMBOL(io_schedule);
3711 
3712 long __sched io_schedule_timeout(long timeout)
3713 {
3714         struct rq *rq = raw_rq();
3715         long ret;
3716 
3717         delayacct_blkio_start();
3718         atomic_inc(&rq->nr_iowait);
3719         blk_flush_plug(current);
3720         current->in_iowait = 1;
3721         ret = schedule_timeout(timeout);
3722         current->in_iowait = 0;
3723         atomic_dec(&rq->nr_iowait);
3724         delayacct_blkio_end();
3725         return ret;
3726 }
3727 
3728 /**
3729  * sys_sched_get_priority_max - return maximum RT priority.
3730  * @policy: scheduling class.
3731  *
3732  * Return: On success, this syscall returns the maximum
3733  * rt_priority that can be used by a given scheduling class.
3734  * On failure, a negative error code is returned.
3735  */
3736 SYSCALL_DEFINE1(sched_get_priority_max, int, policy)
3737 {
3738         int ret = -EINVAL;
3739 
3740         switch (policy) {
3741         case SCHED_FIFO:
3742         case SCHED_RR:
3743                 ret = MAX_USER_RT_PRIO-1;
3744                 break;
3745         case SCHED_NORMAL:
3746         case SCHED_BATCH:
3747         case SCHED_IDLE:
3748                 ret = 0;
3749                 break;
3750         }
3751         return ret;
3752 }
3753 
3754 /**
3755  * sys_sched_get_priority_min - return minimum RT priority.
3756  * @policy: scheduling class.
3757  *
3758  * Return: On success, this syscall returns the minimum
3759  * rt_priority that can be used by a given scheduling class.
3760  * On failure, a negative error code is returned.
3761  */
3762 SYSCALL_DEFINE1(sched_get_priority_min, int, policy)
3763 {
3764         int ret = -EINVAL;
3765 
3766         switch (policy) {
3767         case SCHED_FIFO:
3768         case SCHED_RR:
3769                 ret = 1;
3770                 break;
3771         case SCHED_NORMAL:
3772         case SCHED_BATCH:
3773         case SCHED_IDLE:
3774                 ret = 0;
3775         }
3776         return ret;
3777 }
3778 
3779 /**
3780  * sys_sched_rr_get_interval - return the default timeslice of a process.
3781  * @pid: pid of the process.
3782  * @interval: userspace pointer to the timeslice value.
3783  *
3784  * this syscall writes the default timeslice value of a given process
3785  * into the user-space timespec buffer. A value of '' means infinity.
3786  *
3787  * Return: On success, 0 and the timeslice is in @interval. Otherwise,
3788  * an error code.
3789  */
3790 SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid,
3791                 struct timespec __user *, interval)
3792 {
3793         struct task_struct *p;
3794         unsigned int time_slice;
3795         unsigned long flags;
3796         struct rq *rq;
3797         int retval;
3798         struct timespec t;
3799 
3800         if (pid < 0)
3801                 return -EINVAL;
3802 
3803         retval = -ESRCH;
3804         rcu_read_lock();
3805         p = find_process_by_pid(pid);
3806         if (!p)
3807                 goto out_unlock;
3808 
3809         retval = security_task_getscheduler(p);
3810         if (retval)
3811                 goto out_unlock;
3812 
3813         rq = task_rq_lock(p, &flags);
3814         time_slice = p->sched_class->get_rr_interval(rq, p);
3815         task_rq_unlock(rq, p, &flags);
3816 
3817         rcu_read_unlock();
3818         jiffies_to_timespec(time_slice, &t);
3819         retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0;
3820         return retval;
3821 
3822 out_unlock:
3823         rcu_read_unlock();
3824         return retval;
3825 }
3826 
3827 static const char stat_nam[] = TASK_STATE_TO_CHAR_STR;
3828 
3829 void sched_show_task(struct task_struct *p)
3830 {
3831         unsigned long free = 0;
3832         int ppid;
3833         unsigned state;
3834 
3835         state = p->state ? __ffs(p->state) + 1 : 0;
3836         printk(KERN_INFO "%-15.15s %c", p->comm,
3837                 state < sizeof(stat_nam) - 1 ? stat_nam[state] : '?');
3838 #if BITS_PER_LONG == 32
3839         if (state == TASK_RUNNING)
3840                 printk(KERN_CONT " running  ");
3841         else
3842                 printk(KERN_CONT " %08lx ", thread_saved_pc(p));
3843 #else
3844         if (state == TASK_RUNNING)
3845                 printk(KERN_CONT "  running task    ");
3846         else
3847                 printk(KERN_CONT " %016lx ", thread_saved_pc(p));
3848 #endif
3849 #ifdef CONFIG_DEBUG_STACK_USAGE
3850         free = stack_not_used(p);
3851 #endif
3852         rcu_read_lock();
3853         ppid = task_pid_nr(rcu_dereference(p->real_parent));
3854         rcu_read_unlock();
3855         printk(KERN_CONT "%5lu %5d %6d 0x%08lx\n", free,
3856                 task_pid_nr(p), ppid,
3857                 (unsigned long)task_thread_info(p)->flags);
3858 
3859         print_worker_info(KERN_INFO, p);
3860         show_stack(p, NULL);
3861 }
3862 
3863 void show_state_filter(unsigned long state_filter)
3864 {
3865         struct task_struct *g, *p;
3866 
3867 #if BITS_PER_LONG == 32
3868         printk(KERN_INFO
3869                 "  task                PC stack   pid father\n");
3870 #else
3871         printk(KERN_INFO
3872                 "  task                        PC stack   pid father\n");
3873 #endif
3874         rcu_read_lock();
3875         do_each_thread(g, p) {
3876                 /*
3877                  * reset the NMI-timeout, listing all files on a slow
3878                  * console might take a lot of time:
3879                  */
3880                 touch_nmi_watchdog();
3881                 if (!state_filter || (p->state & state_filter))
3882                         sched_show_task(p);
3883         } while_each_thread(g, p);
3884 
3885         touch_all_softlockup_watchdogs();
3886 
3887 #ifdef CONFIG_SCHED_DEBUG
3888         sysrq_sched_debug_show();
3889 #endif
3890         rcu_read_unlock();
3891         /*
3892          * Only show locks if all tasks are dumped:
3893          */
3894         if (!state_filter)
3895                 debug_show_all_locks();
3896 }
3897 
3898 void init_idle_bootup_task(struct task_struct *idle)
3899 {
3900         idle->sched_class = &idle_sched_class;
3901 }
3902 
3903 /**
3904  * init_idle - set up an idle thread for a given CPU
3905  * @idle: task in question
3906  * @cpu: cpu the idle task belongs to
3907  *
3908  * NOTE: this function does not set the idle thread's NEED_RESCHED
3909  * flag, to make booting more robust.
3910  */
3911 void init_idle(struct task_struct *idle, int cpu)
3912 {
3913         struct rq *rq = cpu_rq(cpu);
3914         unsigned long flags;
3915 
3916         raw_spin_lock_irqsave(&rq->lock, flags);
3917 
3918         __sched_fork(0, idle);
3919         idle->state = TASK_RUNNING;
3920         idle->se.exec_start = sched_clock();
3921 
3922         do_set_cpus_allowed(idle, cpumask_of(cpu));
3923         /*
3924          * We're having a chicken and egg problem, even though we are
3925          * holding rq->lock, the cpu isn't yet set to this cpu so the
3926          * lockdep check in task_group() will fail.
3927          *
3928          * Similar case to sched_fork(). / Alternatively we could
3929          * use task_rq_lock() here and obtain the other rq->lock.
3930          *
3931          * Silence PROVE_RCU
3932          */
3933         rcu_read_lock();
3934         __set_task_cpu(idle, cpu);
3935         rcu_read_unlock();
3936 
3937         rq->curr = rq->idle = idle;
3938 #if defined(CONFIG_SMP)
3939         idle->on_cpu = 1;
3940 #endif
3941         raw_spin_unlock_irqrestore(&rq->lock, flags);
3942 
3943         /* Set the preempt count _outside_ the spinlocks! */
3944         init_idle_preempt_count(idle, cpu);
3945 
3946         /*
3947          * The idle tasks have their own, simple scheduling class:
3948          */
3949         idle->sched_class = &idle_sched_class;
3950         ftrace_graph_init_idle_task(idle, cpu);
3951         vtime_init_idle(idle, cpu);
3952 #if defined(CONFIG_SMP)
3953         sprintf(idle->comm, "%s/%d", INIT_TASK_COMM, cpu);
3954 #endif
3955 }
3956 
3957 #ifdef CONFIG_SMP
3958 void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask)
3959 {
3960         if (p->sched_class && p->sched_class->set_cpus_allowed)
3961                 p->sched_class->set_cpus_allowed(p, new_mask);
3962 
3963         cpumask_copy(&p->cpus_allowed, new_mask);
3964         p->nr_cpus_allowed = cpumask_weight(new_mask);
3965 }
3966 
3967 /*
3968  * This is how migration works:
3969  *
3970  * 1) we invoke migration_cpu_stop() on the target CPU using
3971  *    stop_one_cpu().
3972  * 2) stopper starts to run (implicitly forcing the migrated thread
3973  *    off the CPU)
3974  * 3) it checks whether the migrated task is still in the wrong runqueue.
3975  * 4) if it's in the wrong runqueue then the migration thread removes
3976  *    it and puts it into the right queue.
3977  * 5) stopper completes and stop_one_cpu() returns and the migration
3978  *    is done.
3979  */
3980 
3981 /*
3982  * Change a given task's CPU affinity. Migrate the thread to a
3983  * proper CPU and schedule it away if the CPU it's executing on
3984  * is removed from the allowed bitmask.
3985  *
3986  * NOTE: the caller must have a valid reference to the task, the
3987  * task must not exit() & deallocate itself prematurely. The
3988  * call is not atomic; no spinlocks may be held.
3989  */
3990 int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask)
3991 {
3992         unsigned long flags;
3993         struct rq *rq;
3994         unsigned int dest_cpu;
3995         int ret = 0;
3996 
3997         rq = task_rq_lock(p, &flags);
3998 
3999         if (cpumask_equal(&p->cpus_allowed, new_mask))
4000                 goto out;
4001 
4002         if (!cpumask_intersects(new_mask, cpu_active_mask)) {
4003                 ret = -EINVAL;
4004                 goto out;
4005         }
4006 
4007         do_set_cpus_allowed(p, new_mask);
4008 
4009         /* Can the task run on the task's current CPU? If so, we're done */
4010         if (cpumask_test_cpu(task_cpu(p), new_mask))
4011                 goto out;
4012 
4013         dest_cpu = cpumask_any_and(cpu_active_mask, new_mask);
4014         if (p->on_rq) {
4015                 struct migration_arg arg = { p, dest_cpu };
4016                 /* Need help from migration thread: drop lock and wait. */
4017                 task_rq_unlock(rq, p, &flags);
4018                 stop_one_cpu(cpu_of(rq), migration_cpu_stop, &arg);
4019                 tlb_migrate_finish(p->mm);
4020                 return 0;
4021         }
4022 out:
4023         task_rq_unlock(rq, p, &flags);
4024 
4025         return ret;
4026 }
4027 EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr);
4028 
4029 /*
4030  * Move (not current) task off this cpu, onto dest cpu. We're doing
4031  * this because either it can't run here any more (set_cpus_allowed()
4032  * away from this CPU, or CPU going down), or because we're
4033  * attempting to rebalance this task on exec (sched_exec).
4034  *
4035  * So we race with normal scheduler movements, but that's OK, as long
4036  * as the task is no longer on this CPU.
4037  *
4038  * Returns non-zero if task was successfully migrated.
4039  */
4040 static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu)
4041 {
4042         struct rq *rq_dest, *rq_src;
4043         int ret = 0;
4044 
4045         if (unlikely(!cpu_active(dest_cpu)))
4046                 return ret;
4047 
4048         rq_src = cpu_rq(src_cpu);
4049         rq_dest = cpu_rq(dest_cpu);
4050 
4051         raw_spin_lock(&p->pi_lock);
4052         double_rq_lock(rq_src, rq_dest);
4053         /* Already moved. */
4054         if (task_cpu(p) != src_cpu)
4055                 goto done;
4056         /* Affinity changed (again). */
4057         if (!cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p)))
4058                 goto fail;
4059 
4060         /*
4061          * If we're not on a rq, the next wake-up will ensure we're
4062          * placed properly.
4063          */
4064         if (p->on_rq) {
4065                 dequeue_task(rq_src, p, 0);
4066                 set_task_cpu(p, dest_cpu);
4067                 enqueue_task(rq_dest, p, 0);
4068                 check_preempt_curr(rq_dest, p, 0);
4069         }
4070 done:
4071         ret = 1;
4072 fail:
4073         double_rq_unlock(rq_src, rq_dest);
4074         raw_spin_unlock(&p->pi_lock);
4075         return ret;
4076 }
4077 
4078 #ifdef CONFIG_NUMA_BALANCING
4079 /* Migrate current task p to target_cpu */
4080 int migrate_task_to(struct task_struct *p, int target_cpu)
4081 {
4082         struct migration_arg arg = { p, target_cpu };
4083         int curr_cpu = task_cpu(p);
4084 
4085         if (curr_cpu == target_cpu)
4086                 return 0;
4087 
4088         if (!cpumask_test_cpu(target_cpu, tsk_cpus_allowed(p)))
4089                 return -EINVAL;
4090 
4091         /* TODO: This is not properly updating schedstats */
4092 
4093         return stop_one_cpu(curr_cpu, migration_cpu_stop, &arg);
4094 }
4095 
4096 /*
4097  * Requeue a task on a given node and accurately track the number of NUMA
4098  * tasks on the runqueues
4099  */
4100 void sched_setnuma(struct task_struct *p, int nid)
4101 {
4102         struct rq *rq;
4103         unsigned long flags;
4104         bool on_rq, running;
4105 
4106         rq = task_rq_lock(p, &flags);
4107         on_rq = p->on_rq;
4108         running = task_current(rq, p);
4109 
4110         if (on_rq)
4111                 dequeue_task(rq, p, 0);
4112         if (running)
4113                 p->sched_class->put_prev_task(rq, p);
4114 
4115         p->numa_preferred_nid = nid;
4116 
4117         if (running)
4118                 p->sched_class->set_curr_task(rq);
4119         if (on_rq)
4120                 enqueue_task(rq, p, 0);
4121         task_rq_unlock(rq, p, &flags);
4122 }
4123 #endif
4124 
4125 /*
4126  * migration_cpu_stop - this will be executed by a highprio stopper thread
4127  * and performs thread migration by bumping thread off CPU then
4128  * 'pushing' onto another runqueue.
4129  */
4130 static int migration_cpu_stop(void *data)
4131 {
4132         struct migration_arg *arg = data;
4133 
4134         /*
4135          * The original target cpu might have gone down and we might
4136          * be on another cpu but it doesn't matter.
4137          */
4138         local_irq_disable();
4139         __migrate_task(arg->task, raw_smp_processor_id(), arg->dest_cpu);
4140         local_irq_enable();
4141         return 0;
4142 }
4143 
4144 #ifdef CONFIG_HOTPLUG_CPU
4145 
4146 /*
4147  * Ensures that the idle task is using init_mm right before its cpu goes
4148  * offline.
4149  */
4150 void idle_task_exit(void)
4151 {
4152         struct mm_struct *mm = current->active_mm;
4153 
4154         BUG_ON(cpu_online(smp_processor_id()));
4155 
4156         if (mm != &init_mm)
4157                 switch_mm(mm, &init_mm, current);
4158         mmdrop(mm);
4159 }
4160 
4161 /*
4162  * Since this CPU is going 'away' for a while, fold any nr_active delta
4163  * we might have. Assumes we're called after migrate_tasks() so that the
4164  * nr_active count is stable.
4165  *
4166  * Also see the comment "Global load-average calculations".
4167  */
4168 static void calc_load_migrate(struct rq *rq)
4169 {
4170         long delta = calc_load_fold_active(rq);
4171         if (delta)
4172                 atomic_long_add(delta, &calc_load_tasks);
4173 }
4174 
4175 /*
4176  * Migrate all tasks from the rq, sleeping tasks will be migrated by
4177  * try_to_wake_up()->select_task_rq().
4178  *
4179  * Called with rq->lock held even though we'er in stop_machine() and
4180  * there's no concurrency possible, we hold the required locks anyway
4181  * because of lock validation efforts.
4182  */
4183 static void migrate_tasks(unsigned int dead_cpu)
4184 {
4185         struct rq *rq = cpu_rq(dead_cpu);
4186         struct task_struct *next, *stop = rq->stop;
4187         int dest_cpu;
4188 
4189         /*
4190          * Fudge the rq selection such that the below task selection loop
4191          * doesn't get stuck on the currently eligible stop task.
4192          *
4193          * We're currently inside stop_machine() and the rq is either stuck
4194          * in the stop_machine_cpu_stop() loop, or we're executing this code,
4195          * either way we should never end up calling schedule() until we're
4196          * done here.
4197          */
4198         rq->stop = NULL;
4199 
4200         /*
4201          * put_prev_task() and pick_next_task() sched
4202          * class method both need to have an up-to-date
4203          * value of rq->clock[_task]
4204          */
4205         update_rq_clock(rq);
4206 
4207         for ( ; ; ) {
4208                 /*
4209                  * There's this thread running, bail when that's the only
4210                  * remaining thread.
4211                  */
4212                 if (rq->nr_running == 1)
4213                         break;
4214 
4215                 next = pick_next_task(rq);
4216                 BUG_ON(!next);
4217                 next->sched_class->put_prev_task(rq, next);
4218 
4219                 /* Find suitable destination for @next, with force if needed. */
4220                 dest_cpu = select_fallback_rq(dead_cpu, next);
4221                 raw_spin_unlock(&rq->lock);
4222 
4223                 __migrate_task(next, dead_cpu, dest_cpu);
4224 
4225                 raw_spin_lock(&rq->lock);
4226         }
4227 
4228         rq->stop = stop;
4229 }
4230 
4231 #endif /* CONFIG_HOTPLUG_CPU */
4232 
4233 #if defined(CONFIG_SCHED_DEBUG) && defined(CONFIG_SYSCTL)
4234 
4235 static struct ctl_table sd_ctl_dir[] = {
4236         {
4237                 .procname       = "sched_domain",
4238                 .mode           = 0555,
4239         },
4240         {}
4241 };
4242 
4243 static struct ctl_table sd_ctl_root[] = {
4244         {
4245                 .procname       = "kernel",
4246                 .mode           = 0555,
4247                 .child          = sd_ctl_dir,
4248         },
4249         {}
4250 };
4251 
4252 static struct ctl_table *sd_alloc_ctl_entry(int n)
4253 {
4254         struct ctl_table *entry =
4255                 kcalloc(n, sizeof(struct ctl_table), GFP_KERNEL);
4256 
4257         return entry;
4258 }
4259 
4260 static void sd_free_ctl_entry(struct ctl_table **tablep)
4261 {
4262         struct ctl_table *entry;
4263 
4264         /*
4265          * In the intermediate directories, both the child directory and
4266          * procname are dynamically allocated and could fail but the mode
4267          * will always be set. In the lowest directory the names are
4268          * static strings and all have proc handlers.
4269          */
4270         for (entry = *tablep; entry->mode; entry++) {
4271                 if (entry->child)
4272                         sd_free_ctl_entry(&entry->child);
4273                 if (entry->proc_handler == NULL)
4274                         kfree(entry->procname);
4275         }
4276 
4277         kfree(*tablep);
4278         *tablep = NULL;
4279 }
4280 
4281 static int min_load_idx = 0;
4282 static int max_load_idx = CPU_LOAD_IDX_MAX-1;
4283 
4284 static void
4285 set_table_entry(struct ctl_table *entry,
4286                 const char *procname, void *data, int maxlen,
4287                 umode_t mode, proc_handler *proc_handler,
4288                 bool load_idx)
4289 {
4290         entry->procname = procname;
4291         entry->data = data;
4292         entry->maxlen = maxlen;
4293         entry->mode = mode;
4294         entry->proc_handler = proc_handler;
4295 
4296         if (load_idx) {
4297                 entry->extra1 = &min_load_idx;
4298                 entry->extra2 = &max_load_idx;
4299         }
4300 }
4301 
4302 static struct ctl_table *
4303 sd_alloc_ctl_domain_table(struct sched_domain *sd)
4304 {
4305         struct ctl_table *table = sd_alloc_ctl_entry(13);
4306 
4307         if (table == NULL)
4308                 return NULL;
4309 
4310         set_table_entry(&table[0], "min_interval", &sd->min_interval,
4311                 sizeof(long), 0644, proc_doulongvec_minmax, false);
4312         set_table_entry(&table[1], "max_interval", &sd->max_interval,
4313                 sizeof(long), 0644, proc_doulongvec_minmax, false);
4314         set_table_entry(&table[2], "busy_idx", &sd->busy_idx,
4315                 sizeof(int), 0644, proc_dointvec_minmax, true);
4316         set_table_entry(&table[3], "idle_idx", &sd->idle_idx,
4317                 sizeof(int), 0644, proc_dointvec_minmax, true);
4318         set_table_entry(&table[4], "newidle_idx", &sd->newidle_idx,
4319                 sizeof(int), 0644, proc_dointvec_minmax, true);
4320         set_table_entry(&table[5], "wake_idx", &sd->wake_idx,
4321                 sizeof(int), 0644, proc_dointvec_minmax, true);
4322         set_table_entry(&table[6], "forkexec_idx", &sd->forkexec_idx,
4323                 sizeof(int), 0644, proc_dointvec_minmax, true);
4324         set_table_entry(&table[7], "busy_factor", &sd->busy_factor,
4325                 sizeof(int), 0644, proc_dointvec_minmax, false);
4326         set_table_entry(&table[8], "imbalance_pct", &sd->imbalance_pct,
4327                 sizeof(int), 0644, proc_dointvec_minmax, false);
4328         set_table_entry(&table[9], "cache_nice_tries",
4329                 &sd->cache_nice_tries,
4330                 sizeof(int), 0644, proc_dointvec_minmax, false);
4331         set_table_entry(&table[10], "flags", &sd->flags,
4332                 sizeof(int), 0644, proc_dointvec_minmax, false);
4333         set_table_entry(&table[11], "name", sd->name,
4334                 CORENAME_MAX_SIZE, 0444, proc_dostring, false);
4335         /* &table[12] is terminator */
4336 
4337         return table;
4338 }
4339 
4340 static struct ctl_table *sd_alloc_ctl_cpu_table(int cpu)
4341 {
4342         struct ctl_table *entry, *table;
4343         struct sched_domain *sd;
4344         int domain_num = 0, i;
4345         char buf[32];
4346 
4347         for_each_domain(cpu, sd)
4348                 domain_num++;
4349         entry = table = sd_alloc_ctl_entry(domain_num + 1);
4350         if (table == NULL)
4351                 return NULL;
4352 
4353         i = 0;
4354         for_each_domain(cpu, sd) {
4355                 snprintf(buf, 32, "domain%d", i);
4356                 entry->procname = kstrdup(buf, GFP_KERNEL);
4357                 entry->mode = 0555;
4358                 entry->child = sd_alloc_ctl_domain_table(sd);
4359                 entry++;
4360                 i++;
4361         }
4362         return table;
4363 }
4364 
4365 static struct ctl_table_header *sd_sysctl_header;
4366 static void register_sched_domain_sysctl(void)
4367 {
4368         int i, cpu_num = num_possible_cpus();
4369         struct ctl_table *entry = sd_alloc_ctl_entry(cpu_num + 1);
4370         char buf[32];
4371 
4372         WARN_ON(sd_ctl_dir[0].child);
4373         sd_ctl_dir[0].child = entry;
4374 
4375         if (entry == NULL)
4376                 return;
4377 
4378         for_each_possible_cpu(i) {
4379                 snprintf(buf, 32, "cpu%d", i);
4380                 entry->procname = kstrdup(buf, GFP_KERNEL);
4381                 entry->mode = 0555;
4382                 entry->child = sd_alloc_ctl_cpu_table(i);
4383                 entry++;
4384         }
4385 
4386         WARN_ON(sd_sysctl_header);
4387         sd_sysctl_header = register_sysctl_table(sd_ctl_root);
4388 }
4389 
4390 /* may be called multiple times per register */
4391 static void unregister_sched_domain_sysctl(void)
4392 {
4393         if (sd_sysctl_header)
4394                 unregister_sysctl_table(sd_sysctl_header);
4395         sd_sysctl_header = NULL;
4396         if (sd_ctl_dir[0].child)
4397                 sd_free_ctl_entry(&sd_ctl_dir[0].child);
4398 }
4399 #else
4400 static void register_sched_domain_sysctl(void)
4401 {
4402 }
4403 static void unregister_sched_domain_sysctl(void)
4404 {
4405 }
4406 #endif
4407 
4408 static void set_rq_online(struct rq *rq)
4409 {
4410         if (!rq->online) {
4411                 const struct sched_class *class;
4412 
4413                 cpumask_set_cpu(rq->cpu, rq->rd->online);
4414                 rq->online = 1;
4415 
4416                 for_each_class(class) {
4417                         if (class->rq_online)
4418                                 class->rq_online(rq);
4419                 }
4420         }
4421 }
4422 
4423 static void set_rq_offline(struct rq *rq)
4424 {
4425         if (rq->online) {
4426                 const struct sched_class *class;
4427 
4428                 for_each_class(class) {
4429                         if (class->rq_offline)
4430                                 class->rq_offline(rq);
4431                 }
4432 
4433                 cpumask_clear_cpu(rq->cpu, rq->rd->online);
4434                 rq->online = 0;
4435         }
4436 }
4437 
4438 /*
4439  * migration_call - callback that gets triggered when a CPU is added.
4440  * Here we can start up the necessary migration thread for the new CPU.
4441  */
4442 static int
4443 migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)
4444 {
4445         int cpu = (long)hcpu;
4446         unsigned long flags;
4447         struct rq *rq = cpu_rq(cpu);
4448 
4449         switch (action & ~CPU_TASKS_FROZEN) {
4450 
4451         case CPU_UP_PREPARE:
4452                 rq->calc_load_update = calc_load_update;
4453                 break;
4454 
4455         case CPU_ONLINE:
4456                 /* Update our root-domain */
4457                 raw_spin_lock_irqsave(&rq->lock, flags);
4458                 if (rq->rd) {
4459                         BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
4460 
4461                         set_rq_online(rq);
4462                 }
4463                 raw_spin_unlock_irqrestore(&rq->lock, flags);
4464                 break;
4465 
4466 #ifdef CONFIG_HOTPLUG_CPU
4467         case CPU_DYING:
4468                 sched_ttwu_pending();
4469                 /* Update our root-domain */
4470                 raw_spin_lock_irqsave(&rq->lock, flags);
4471                 if (rq->rd) {
4472                         BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
4473                         set_rq_offline(rq);
4474                 }
4475                 migrate_tasks(cpu);
4476                 BUG_ON(rq->nr_running != 1); /* the migration thread */
4477                 raw_spin_unlock_irqrestore(&rq->lock, flags);
4478                 break;
4479 
4480         case CPU_DEAD:
4481                 calc_load_migrate(rq);
4482                 break;
4483 #endif
4484         }
4485 
4486         update_max_interval();
4487 
4488         return NOTIFY_OK;
4489 }
4490 
4491 /*
4492  * Register at high priority so that task migration (migrate_all_tasks)
4493  * happens before everything else.  This has to be lower priority than
4494  * the notifier in the perf_event subsystem, though.
4495  */
4496 static struct notifier_block migration_notifier = {
4497         .notifier_call = migration_call,
4498         .priority = CPU_PRI_MIGRATION,
4499 };
4500 
4501 static int sched_cpu_active(struct notifier_block *nfb,
4502                                       unsigned long action, void *hcpu)
4503 {
4504         switch (action & ~CPU_TASKS_FROZEN) {
4505         case CPU_STARTING:
4506         case CPU_DOWN_FAILED:
4507                 set_cpu_active((long)hcpu, true);
4508                 return NOTIFY_OK;
4509         default:
4510                 return NOTIFY_DONE;
4511         }
4512 }
4513 
4514 static int sched_cpu_inactive(struct notifier_block *nfb,
4515                                         unsigned long action, void *hcpu)
4516 {
4517         switch (action & ~CPU_TASKS_FROZEN) {
4518         case CPU_DOWN_PREPARE:
4519                 set_cpu_active((long)hcpu, false);
4520                 return NOTIFY_OK;
4521         default:
4522                 return NOTIFY_DONE;
4523         }
4524 }
4525 
4526 static int __init migration_init(void)
4527 {
4528         void *cpu = (void *)(long)smp_processor_id();
4529         int err;
4530 
4531         /* Initialize migration for the boot CPU */
4532         err = migration_call(&migration_notifier, CPU_UP_PREPARE, cpu);
4533         BUG_ON(err == NOTIFY_BAD);
4534         migration_call(&migration_notifier, CPU_ONLINE, cpu);
4535         register_cpu_notifier(&migration_notifier);
4536 
4537         /* Register cpu active notifiers */
4538         cpu_notifier(sched_cpu_active, CPU_PRI_SCHED_ACTIVE);
4539         cpu_notifier(sched_cpu_inactive, CPU_PRI_SCHED_INACTIVE);
4540 
4541         return 0;
4542 }
4543 early_initcall(migration_init);
4544 #endif
4545 
4546 #ifdef CONFIG_SMP
4547 
4548 static cpumask_var_t sched_domains_tmpmask; /* sched_domains_mutex */
4549 
4550 #ifdef CONFIG_SCHED_DEBUG
4551 
4552 static __read_mostly int sched_debug_enabled;
4553 
4554 static int __init sched_debug_setup(char *str)
4555 {
4556         sched_debug_enabled = 1;
4557 
4558         return 0;
4559 }
4560 early_param("sched_debug", sched_debug_setup);
4561 
4562 static inline bool sched_debug(void)
4563 {
4564         return sched_debug_enabled;
4565 }
4566 
4567 static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level,
4568                                   struct cpumask *groupmask)
4569 {
4570         struct sched_group *group = sd->groups;
4571         char str[256];
4572 
4573         cpulist_scnprintf(str, sizeof(str), sched_domain_span(sd));
4574         cpumask_clear(groupmask);
4575 
4576         printk(KERN_DEBUG "%*s domain %d: ", level, "", level);
4577 
4578         if (!(sd->flags & SD_LOAD_BALANCE)) {
4579                 printk("does not load-balance\n");
4580                 if (sd->parent)
4581                         printk(KERN_ERR "ERROR: !SD_LOAD_BALANCE domain"
4582                                         " has parent");
4583                 return -1;
4584         }
4585 
4586         printk(KERN_CONT "span %s level %s\n", str, sd->name);
4587 
4588         if (!cpumask_test_cpu(cpu, sched_domain_span(sd))) {
4589                 printk(KERN_ERR "ERROR: domain->span does not contain "
4590                                 "CPU%d\n", cpu);
4591         }
4592         if (!cpumask_test_cpu(cpu, sched_group_cpus(group))) {
4593                 printk(KERN_ERR "ERROR: domain->groups does not contain"
4594                                 " CPU%d\n", cpu);
4595         }
4596 
4597         printk(KERN_DEBUG "%*s groups:", level + 1, "");
4598         do {
4599                 if (!group) {
4600                         printk("\n");
4601                         printk(KERN_ERR "ERROR: group is NULL\n");
4602                         break;
4603                 }
4604 
4605                 /*
4606                  * Even though we initialize ->power to something semi-sane,
4607                  * we leave power_orig unset. This allows us to detect if
4608                  * domain iteration is still funny without causing /0 traps.
4609                  */
4610                 if (!group->sgp->power_orig) {
4611                         printk(KERN_CONT "\n");
4612                         printk(KERN_ERR "ERROR: domain->cpu_power not "
4613                                         "set\n");
4614                         break;
4615                 }
4616 
4617                 if (!cpumask_weight(sched_group_cpus(group))) {
4618                         printk(KERN_CONT "\n");
4619                         printk(KERN_ERR "ERROR: empty group\n");
4620                         break;
4621                 }
4622 
4623                 if (!(sd->flags & SD_OVERLAP) &&
4624                     cpumask_intersects(groupmask, sched_group_cpus(group))) {
4625                         printk(KERN_CONT "\n");
4626                         printk(KERN_ERR "ERROR: repeated CPUs\n");
4627                         break;
4628                 }
4629 
4630                 cpumask_or(groupmask, groupmask, sched_group_cpus(group));
4631 
4632                 cpulist_scnprintf(str, sizeof(str), sched_group_cpus(group));
4633 
4634                 printk(KERN_CONT " %s", str);
4635                 if (group->sgp->power != SCHED_POWER_SCALE) {
4636                         printk(KERN_CONT " (cpu_power = %d)",
4637                                 group->sgp->power);
4638                 }
4639 
4640                 group = group->next;
4641         } while (group != sd->groups);
4642         printk(KERN_CONT "\n");
4643 
4644         if (!cpumask_equal(sched_domain_span(sd), groupmask))
4645                 printk(KERN_ERR "ERROR: groups don't span domain->span\n");
4646 
4647         if (sd->parent &&
4648             !cpumask_subset(groupmask, sched_domain_span(sd->parent)))
4649                 printk(KERN_ERR "ERROR: parent span is not a superset "
4650                         "of domain->span\n");
4651         return 0;
4652 }
4653 
4654 static void sched_domain_debug(struct sched_domain *sd, int cpu)
4655 {
4656         int level = 0;
4657 
4658         if (!sched_debug_enabled)
4659                 return;
4660 
4661         if (!sd) {
4662                 printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu);
4663                 return;
4664         }
4665 
4666         printk(KERN_DEBUG "CPU%d attaching sched-domain:\n", cpu);
4667 
4668         for (;;) {
4669                 if (sched_domain_debug_one(sd, cpu, level, sched_domains_tmpmask))
4670                         break;
4671                 level++;
4672                 sd = sd->parent;
4673                 if (!sd)
4674                         break;
4675         }
4676 }
4677 #else /* !CONFIG_SCHED_DEBUG */
4678 # define sched_domain_debug(sd, cpu) do { } while (0)
4679 static inline bool sched_debug(void)
4680 {
4681         return false;
4682 }
4683 #endif /* CONFIG_SCHED_DEBUG */
4684 
4685 static int sd_degenerate(struct sched_domain *sd)
4686 {
4687         if (cpumask_weight(sched_domain_span(sd)) == 1)
4688                 return 1;
4689 
4690         /* Following flags need at least 2 groups */
4691         if (sd->flags & (SD_LOAD_BALANCE |
4692                          SD_BALANCE_NEWIDLE |
4693                          SD_BALANCE_FORK |
4694                          SD_BALANCE_EXEC |
4695                          SD_SHARE_CPUPOWER |
4696                          SD_SHARE_PKG_RESOURCES)) {
4697                 if (sd->groups != sd->groups->next)
4698                         return 0;
4699         }
4700 
4701         /* Following flags don't use groups */
4702         if (sd->flags & (SD_WAKE_AFFINE))
4703                 return 0;
4704 
4705         return 1;
4706 }
4707 
4708 static int
4709 sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent)
4710 {
4711         unsigned long cflags = sd->flags, pflags = parent->flags;
4712 
4713         if (sd_degenerate(parent))
4714                 return 1;
4715 
4716         if (!cpumask_equal(sched_domain_span(sd), sched_domain_span(parent)))
4717                 return 0;
4718 
4719         /* Flags needing groups don't count if only 1 group in parent */
4720         if (parent->groups == parent->groups->next) {
4721                 pflags &= ~(SD_LOAD_BALANCE |
4722                                 SD_BALANCE_NEWIDLE |
4723                                 SD_BALANCE_FORK |
4724                                 SD_BALANCE_EXEC |
4725                                 SD_SHARE_CPUPOWER |
4726                                 SD_SHARE_PKG_RESOURCES |
4727                                 SD_PREFER_SIBLING);
4728                 if (nr_node_ids == 1)
4729                         pflags &= ~SD_SERIALIZE;
4730         }
4731         if (~cflags & pflags)
4732                 return 0;
4733 
4734         return 1;
4735 }
4736 
4737 static void free_rootdomain(struct rcu_head *rcu)
4738 {
4739         struct root_domain *rd = container_of(rcu, struct root_domain, rcu);
4740 
4741         cpupri_cleanup(&rd->cpupri);
4742         free_cpumask_var(rd->rto_mask);
4743         free_cpumask_var(rd->online);
4744         free_cpumask_var(rd->span);
4745         kfree(rd);
4746 }
4747 
4748 static void rq_attach_root(struct rq *rq, struct root_domain *rd)
4749 {
4750         struct root_domain *old_rd = NULL;
4751         unsigned long flags;
4752 
4753         raw_spin_lock_irqsave(&rq->lock, flags);
4754 
4755         if (rq->rd) {
4756                 old_rd = rq->rd;
4757 
4758                 if (cpumask_test_cpu(rq->cpu, old_rd->online))
4759                         set_rq_offline(rq);
4760 
4761                 cpumask_clear_cpu(rq->cpu, old_rd->span);
4762 
4763                 /*
4764                  * If we dont want to free the old_rd yet then
4765                  * set old_rd to NULL to skip the freeing later
4766                  * in this function:
4767                  */
4768                 if (!atomic_dec_and_test(&old_rd->refcount))
4769                         old_rd = NULL;
4770         }
4771 
4772         atomic_inc(&rd->refcount);
4773         rq->rd = rd;
4774 
4775         cpumask_set_cpu(rq->cpu, rd->span);
4776         if (cpumask_test_cpu(rq->cpu, cpu_active_mask))
4777                 set_rq_online(rq);
4778 
4779         raw_spin_unlock_irqrestore(&rq->lock, flags);
4780 
4781         if (old_rd)
4782                 call_rcu_sched(&old_rd->rcu, free_rootdomain);
4783 }
4784 
4785 static int init_rootdomain(struct root_domain *rd)
4786 {
4787         memset(rd, 0, sizeof(*rd));
4788 
4789         if (!alloc_cpumask_var(&rd->span, GFP_KERNEL))
4790                 goto out;
4791         if (!alloc_cpumask_var(&rd->online, GFP_KERNEL))
4792                 goto free_span;
4793         if (!alloc_cpumask_var(&rd->rto_mask, GFP_KERNEL))
4794                 goto free_online;
4795 
4796         if (cpupri_init(&rd->cpupri) != 0)
4797                 goto free_rto_mask;
4798         return 0;
4799 
4800 free_rto_mask:
4801         free_cpumask_var(rd->rto_mask);
4802 free_online:
4803         free_cpumask_var(rd->online);
4804 free_span:
4805         free_cpumask_var(rd->span);
4806 out:
4807         return -ENOMEM;
4808 }
4809 
4810 /*
4811  * By default the system creates a single root-domain with all cpus as
4812  * members (mimicking the global state we have today).
4813  */
4814 struct root_domain def_root_domain;
4815 
4816 static void init_defrootdomain(void)
4817 {
4818         init_rootdomain(&def_root_domain);
4819 
4820         atomic_set(&def_root_domain.refcount, 1);
4821 }
4822 
4823 static struct root_domain *alloc_rootdomain(void)
4824 {
4825         struct root_domain *rd;
4826 
4827         rd = kmalloc(sizeof(*rd), GFP_KERNEL);
4828         if (!rd)
4829                 return NULL;
4830 
4831         if (init_rootdomain(rd) != 0) {
4832                 kfree(rd);
4833                 return NULL;
4834         }
4835 
4836         return rd;
4837 }
4838 
4839 static void free_sched_groups(struct sched_group *sg, int free_sgp)
4840 {
4841         struct sched_group *tmp, *first;
4842 
4843         if (!sg)
4844                 return;
4845 
4846         first = sg;
4847         do {
4848                 tmp = sg->next;
4849 
4850                 if (free_sgp && atomic_dec_and_test(&sg->sgp->ref))
4851                         kfree(sg->sgp);
4852 
4853                 kfree(sg);
4854                 sg = tmp;
4855         } while (sg != first);
4856 }
4857 
4858 static void free_sched_domain(struct rcu_head *rcu)
4859 {
4860         struct sched_domain *sd = container_of(rcu, struct sched_domain, rcu);
4861 
4862         /*
4863          * If its an overlapping domain it has private groups, iterate and
4864          * nuke them all.
4865          */
4866         if (sd->flags & SD_OVERLAP) {
4867                 free_sched_groups(sd->groups, 1);
4868         } else if (atomic_dec_and_test(&sd->groups->ref)) {
4869                 kfree(sd->groups->sgp);
4870                 kfree(sd->groups);
4871         }
4872         kfree(sd);
4873 }
4874 
4875 static void destroy_sched_domain(struct sched_domain *sd, int cpu)
4876 {
4877         call_rcu(&sd->rcu, free_sched_domain);
4878 }
4879 
4880 static void destroy_sched_domains(struct sched_domain *sd, int cpu)
4881 {
4882         for (; sd; sd = sd->parent)
4883                 destroy_sched_domain(sd, cpu);
4884 }
4885 
4886 /*
4887  * Keep a special pointer to the highest sched_domain that has
4888  * SD_SHARE_PKG_RESOURCE set (Last Level Cache Domain) for this
4889  * allows us to avoid some pointer chasing select_idle_sibling().
4890  *
4891  * Also keep a unique ID per domain (we use the first cpu number in
4892  * the cpumask of the domain), this allows us to quickly tell if
4893  * two cpus are in the same cache domain, see cpus_share_cache().
4894  */
4895 DEFINE_PER_CPU(struct sched_domain *, sd_llc);
4896 DEFINE_PER_CPU(int, sd_llc_size);
4897 DEFINE_PER_CPU(int, sd_llc_id);
4898 DEFINE_PER_CPU(struct sched_domain *, sd_numa);
4899 DEFINE_PER_CPU(struct sched_domain *, sd_busy);
4900 DEFINE_PER_CPU(struct sched_domain *, sd_asym);
4901 
4902 static void update_top_cache_domain(int cpu)
4903 {
4904         struct sched_domain *sd;
4905         struct sched_domain *busy_sd = NULL;
4906         int id = cpu;
4907         int size = 1;
4908 
4909         sd = highest_flag_domain(cpu, SD_SHARE_PKG_RESOURCES);
4910         if (sd) {
4911                 id = cpumask_first(sched_domain_span(sd));
4912                 size = cpumask_weight(sched_domain_span(sd));
4913                 busy_sd = sd->parent; /* sd_busy */
4914         }
4915         rcu_assign_pointer(per_cpu(sd_busy, cpu), busy_sd);
4916 
4917         rcu_assign_pointer(per_cpu(sd_llc, cpu), sd);
4918         per_cpu(sd_llc_size, cpu) = size;
4919         per_cpu(sd_llc_id, cpu) = id;
4920 
4921         sd = lowest_flag_domain(cpu, SD_NUMA);
4922         rcu_assign_pointer(per_cpu(sd_numa, cpu), sd);
4923 
4924         sd = highest_flag_domain(cpu, SD_ASYM_PACKING);
4925         rcu_assign_pointer(per_cpu(sd_asym, cpu), sd);
4926 }
4927 
4928 /*
4929  * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
4930  * hold the hotplug lock.
4931  */
4932 static void
4933 cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu)
4934 {
4935         struct rq *rq = cpu_rq(cpu);
4936         struct sched_domain *tmp;
4937 
4938         /* Remove the sched domains which do not contribute to scheduling. */
4939         for (tmp = sd; tmp; ) {
4940                 struct sched_domain *parent = tmp->parent;
4941                 if (!parent)
4942                         break;
4943 
4944                 if (sd_parent_degenerate(tmp, parent)) {
4945                         tmp->parent = parent->parent;
4946                         if (parent->parent)
4947                                 parent->parent->child = tmp;
4948                         /*
4949                          * Transfer SD_PREFER_SIBLING down in case of a
4950                          * degenerate parent; the spans match for this
4951                          * so the property transfers.
4952                          */
4953                         if (parent->flags & SD_PREFER_SIBLING)
4954                                 tmp->flags |= SD_PREFER_SIBLING;
4955                         destroy_sched_domain(parent, cpu);
4956                 } else
4957                         tmp = tmp->parent;
4958         }
4959 
4960         if (sd && sd_degenerate(sd)) {
4961                 tmp = sd;
4962                 sd = sd->parent;
4963                 destroy_sched_domain(tmp, cpu);
4964                 if (sd)
4965                         sd->child = NULL;
4966         }
4967 
4968         sched_domain_debug(sd, cpu);
4969 
4970         rq_attach_root(rq, rd);
4971         tmp = rq->sd;
4972         rcu_assign_pointer(rq->sd, sd);
4973         destroy_sched_domains(tmp, cpu);
4974 
4975         update_top_cache_domain(cpu);
4976 }
4977 
4978 /* cpus with isolated domains */
4979 static cpumask_var_t cpu_isolated_map;
4980 
4981 /* Setup the mask of cpus configured for isolated domains */
4982 static int __init isolated_cpu_setup(char *str)
4983 {
4984         alloc_bootmem_cpumask_var(&cpu_isolated_map);
4985         cpulist_parse(str, cpu_isolated_map);
4986         return 1;
4987 }
4988 
4989 __setup("isolcpus=", isolated_cpu_setup);
4990 
4991 static const struct cpumask *cpu_cpu_mask(int cpu)
4992 {
4993         return cpumask_of_node(cpu_to_node(cpu));
4994 }
4995 
4996 struct sd_data {
4997         struct sched_domain **__percpu sd;
4998         struct sched_group **__percpu sg;
4999         struct sched_group_power **__percpu sgp;
5000 };
5001 
5002 struct s_data {
5003         struct sched_domain ** __percpu sd;
5004         struct root_domain      *rd;
5005 };
5006 
5007 enum s_alloc {
5008         sa_rootdomain,
5009         sa_sd,
5010         sa_sd_storage,
5011         sa_none,
5012 };
5013 
5014 struct sched_domain_topology_level;
5015 
5016 typedef struct sched_domain *(*sched_domain_init_f)(struct sched_domain_topology_level *tl, int cpu);
5017 typedef const struct cpumask *(*sched_domain_mask_f)(int cpu);
5018 
5019 #define SDTL_OVERLAP    0x01
5020 
5021 struct sched_domain_topology_level {
5022         sched_domain_init_f init;
5023         sched_domain_mask_f mask;
5024         int                 flags;
5025         int                 numa_level;
5026         struct sd_data      data;
5027 };
5028 
5029 /*
5030  * Build an iteration mask that can exclude certain CPUs from the upwards
5031  * domain traversal.
5032  *
5033  * Asymmetric node setups can result in situations where the domain tree is of
5034  * unequal depth, make sure to skip domains that already cover the entire
5035  * range.
5036  *
5037  * In that case build_sched_domains() will have terminated the iteration early
5038  * and our sibling sd spans will be empty. Domains should always include the
5039  * cpu they're built on, so check that.
5040  *
5041  */
5042 static void build_group_mask(struct sched_domain *sd, struct sched_group *sg)
5043 {
5044         const struct cpumask *span = sched_domain_span(sd);
5045         struct sd_data *sdd = sd->private;
5046         struct sched_domain *sibling;
5047         int i;
5048 
5049         for_each_cpu(i, span) {
5050                 sibling = *per_cpu_ptr(sdd->sd, i);
5051                 if (!cpumask_test_cpu(i, sched_domain_span(sibling)))
5052                         continue;
5053 
5054                 cpumask_set_cpu(i, sched_group_mask(sg));
5055         }
5056 }
5057 
5058 /*
5059  * Return the canonical balance cpu for this group, this is the first cpu
5060  * of this group that's also in the iteration mask.
5061  */
5062 int group_balance_cpu(struct sched_group *sg)
5063 {
5064         return cpumask_first_and(sched_group_cpus(sg), sched_group_mask(sg));
5065 }
5066 
5067 static int
5068 build_overlap_sched_groups(struct sched_domain *sd, int cpu)
5069 {
5070         struct sched_group *first = NULL, *last = NULL, *groups = NULL, *sg;
5071         const struct cpumask *span = sched_domain_span(sd);
5072         struct cpumask *covered = sched_domains_tmpmask;
5073         struct sd_data *sdd = sd->private;
5074         struct sched_domain *child;
5075         int i;
5076 
5077         cpumask_clear(covered);
5078 
5079         for_each_cpu(i, span) {
5080                 struct cpumask *sg_span;
5081 
5082                 if (cpumask_test_cpu(i, covered))
5083                         continue;
5084 
5085                 child = *per_cpu_ptr(sdd->sd, i);
5086 
5087                 /* See the comment near build_group_mask(). */
5088                 if (!cpumask_test_cpu(i, sched_domain_span(child)))
5089                         continue;
5090 
5091                 sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
5092                                 GFP_KERNEL, cpu_to_node(cpu));
5093 
5094                 if (!sg)
5095                         goto fail;
5096 
5097                 sg_span = sched_group_cpus(sg);
5098                 if (child->child) {
5099                         child = child->child;
5100                         cpumask_copy(sg_span, sched_domain_span(child));
5101                 } else
5102                         cpumask_set_cpu(i, sg_span);
5103 
5104                 cpumask_or(covered, covered, sg_span);
5105 
5106                 sg->sgp = *per_cpu_ptr(sdd->sgp, i);
5107                 if (atomic_inc_return(&sg->sgp->ref) == 1)
5108                         build_group_mask(sd, sg);
5109 
5110                 /*
5111                  * Initialize sgp->power such that even if we mess up the
5112                  * domains and no possible iteration will get us here, we won't
5113                  * die on a /0 trap.
5114                  */
5115                 sg->sgp->power = SCHED_POWER_SCALE * cpumask_weight(sg_span);
5116                 sg->sgp->power_orig = sg->sgp->power;
5117 
5118                 /*
5119                  * Make sure the first group of this domain contains the
5120                  * canonical balance cpu. Otherwise the sched_domain iteration
5121                  * breaks. See update_sg_lb_stats().
5122                  */
5123                 if ((!groups && cpumask_test_cpu(cpu, sg_span)) ||
5124                     group_balance_cpu(sg) == cpu)
5125                         groups = sg;
5126 
5127                 if (!first)
5128                         first = sg;
5129                 if (last)
5130                         last->next = sg;
5131                 last = sg;
5132                 last->next = first;
5133         }
5134         sd->groups = groups;
5135 
5136         return 0;
5137 
5138 fail:
5139         free_sched_groups(first, 0);
5140 
5141         return -ENOMEM;
5142 }
5143 
5144 static int get_group(int cpu, struct sd_data *sdd, struct sched_group **sg)
5145 {
5146         struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu);
5147         struct sched_domain *child = sd->child;
5148 
5149         if (child)
5150                 cpu = cpumask_first(sched_domain_span(child));
5151 
5152         if (sg) {
5153                 *sg = *per_cpu_ptr(sdd->sg, cpu);
5154                 (*sg)->sgp = *per_cpu_ptr(sdd->sgp, cpu);
5155                 atomic_set(&(*sg)->sgp->ref, 1); /* for claim_allocations */
5156         }
5157 
5158         return cpu;
5159 }
5160 
5161 /*
5162  * build_sched_groups will build a circular linked list of the groups
5163  * covered by the given span, and will set each group's ->cpumask correctly,
5164  * and ->cpu_power to 0.
5165  *
5166  * Assumes the sched_domain tree is fully constructed
5167  */
5168 static int
5169 build_sched_groups(struct sched_domain *sd, int cpu)
5170 {
5171         struct sched_group *first = NULL, *last = NULL;
5172         struct sd_data *sdd = sd->private;
5173         const struct cpumask *span = sched_domain_span(sd);
5174         struct cpumask *covered;
5175         int i;
5176 
5177         get_group(cpu, sdd, &sd->groups);
5178         atomic_inc(&sd->groups->ref);
5179 
5180         if (cpu != cpumask_first(span))
5181                 return 0;
5182 
5183         lockdep_assert_held(&sched_domains_mutex);
5184         covered = sched_domains_tmpmask;
5185 
5186         cpumask_clear(covered);
5187 
5188         for_each_cpu(i, span) {
5189                 struct sched_group *sg;
5190                 int group, j;
5191 
5192                 if (cpumask_test_cpu(i, covered))
5193                         continue;
5194 
5195                 group = get_group(i, sdd, &sg);
5196                 cpumask_clear(sched_group_cpus(sg));
5197                 sg->sgp->power = 0;
5198                 cpumask_setall(sched_group_mask(sg));
5199 
5200                 for_each_cpu(j, span) {
5201                         if (get_group(j, sdd, NULL) != group)
5202                                 continue;
5203 
5204                         cpumask_set_cpu(j, covered);
5205                         cpumask_set_cpu(j, sched_group_cpus(sg));
5206                 }
5207 
5208                 if (!first)
5209                         first = sg;
5210                 if (last)
5211                         last->next = sg;
5212                 last = sg;
5213         }
5214         last->next = first;
5215 
5216         return 0;
5217 }
5218 
5219 /*
5220  * Initialize sched groups cpu_power.
5221  *
5222  * cpu_power indicates the capacity of sched group, which is used while
5223  * distributing the load between different sched groups in a sched domain.
5224  * Typically cpu_power for all the groups in a sched domain will be same unless
5225  * there are asymmetries in the topology. If there are asymmetries, group
5226  * having more cpu_power will pickup more load compared to the group having
5227  * less cpu_power.
5228  */
5229 static void init_sched_groups_power(int cpu, struct sched_domain *sd)
5230 {
5231         struct sched_group *sg = sd->groups;
5232 
5233         WARN_ON(!sg);
5234 
5235         do {
5236                 sg->group_weight = cpumask_weight(sched_group_cpus(sg));
5237                 sg = sg->next;
5238         } while (sg != sd->groups);
5239 
5240         if (cpu != group_balance_cpu(sg))
5241                 return;
5242 
5243         update_group_power(sd, cpu);
5244         atomic_set(&sg->sgp->nr_busy_cpus, sg->group_weight);
5245 }
5246 
5247 int __weak arch_sd_sibling_asym_packing(void)
5248 {
5249        return 0*SD_ASYM_PACKING;
5250 }
5251 
5252 /*
5253  * Initializers for schedule domains
5254  * Non-inlined to reduce accumulated stack pressure in build_sched_domains()
5255  */
5256 
5257 #ifdef CONFIG_SCHED_DEBUG
5258 # define SD_INIT_NAME(sd, type)         sd->name = #type
5259 #else
5260 # define SD_INIT_NAME(sd, type)         do { } while (0)
5261 #endif
5262 
5263 #define SD_INIT_FUNC(type)                                              \
5264 static noinline struct sched_domain *                                   \
5265 sd_init_##type(struct sched_domain_topology_level *tl, int cpu)         \
5266 {                                                                       \
5267         struct sched_domain *sd = *per_cpu_ptr(tl->data.sd, cpu);       \
5268         *sd = SD_##type##_INIT;                                         \
5269         SD_INIT_NAME(sd, type);                                         \
5270         sd->private = &tl->data;                                        \
5271         return sd;                                                      \
5272 }
5273 
5274 SD_INIT_FUNC(CPU)
5275 #ifdef CONFIG_SCHED_SMT
5276  SD_INIT_FUNC(SIBLING)
5277 #endif
5278 #ifdef CONFIG_SCHED_MC
5279  SD_INIT_FUNC(MC)
5280 #endif
5281 #ifdef CONFIG_SCHED_BOOK
5282  SD_INIT_FUNC(BOOK)
5283 #endif
5284 
5285 static int default_relax_domain_level = -1;
5286 int sched_domain_level_max;
5287 
5288 static int __init setup_relax_domain_level(char *str)
5289 {
5290         if (kstrtoint(str, 0, &default_relax_domain_level))
5291                 pr_warn("Unable to set relax_domain_level\n");
5292 
5293         return 1;
5294 }
5295 __setup("relax_domain_level=", setup_relax_domain_level);
5296 
5297 static void set_domain_attribute(struct sched_domain *sd,
5298                                  struct sched_domain_attr *attr)
5299 {
5300         int request;
5301 
5302         if (!attr || attr->relax_domain_level < 0) {
5303                 if (default_relax_domain_level < 0)
5304                         return;
5305                 else
5306                         request = default_relax_domain_level;
5307         } else
5308                 request = attr->relax_domain_level;
5309         if (request < sd->level) {
5310                 /* turn off idle balance on this domain */
5311                 sd->flags &= ~(SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
5312         } else {
5313                 /* turn on idle balance on this domain */
5314                 sd->flags |= (SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
5315         }
5316 }
5317 
5318 static void __sdt_free(const struct cpumask *cpu_map);
5319 static int __sdt_alloc(const struct cpumask *cpu_map);
5320 
5321 static void __free_domain_allocs(struct s_data *d, enum s_alloc what,
5322                                  const struct cpumask *cpu_map)
5323 {
5324         switch (what) {
5325         case sa_rootdomain:
5326                 if (!atomic_read(&d->rd->refcount))
5327                         free_rootdomain(&d->rd->rcu); /* fall through */
5328         case sa_sd:
5329                 free_percpu(d->sd); /* fall through */
5330         case sa_sd_storage:
5331                 __sdt_free(cpu_map); /* fall through */
5332         case sa_none:
5333                 break;
5334         }
5335 }
5336 
5337 static enum s_alloc __visit_domain_allocation_hell(struct s_data *d,
5338                                                    const struct cpumask *cpu_map)
5339 {
5340         memset(d, 0, sizeof(*d));
5341 
5342         if (__sdt_alloc(cpu_map))
5343                 return sa_sd_storage;
5344         d->sd = alloc_percpu(struct sched_domain *);
5345         if (!d->sd)
5346                 return sa_sd_storage;
5347         d->rd = alloc_rootdomain();
5348         if (!d->rd)
5349                 return sa_sd;
5350         return sa_rootdomain;
5351 }
5352 
5353 /*
5354  * NULL the sd_data elements we've used to build the sched_domain and
5355  * sched_group structure so that the subsequent __free_domain_allocs()
5356  * will not free the data we're using.
5357  */
5358 static void claim_allocations(int cpu, struct sched_domain *sd)
5359 {
5360         struct sd_data *sdd = sd->private;
5361 
5362         WARN_ON_ONCE(*per_cpu_ptr(sdd->sd, cpu) != sd);
5363         *per_cpu_ptr(sdd->sd, cpu) = NULL;
5364 
5365         if (atomic_read(&(*per_cpu_ptr(sdd->sg, cpu))->ref))
5366                 *per_cpu_ptr(sdd->sg, cpu) = NULL;
5367 
5368         if (atomic_read(&(*per_cpu_ptr(sdd->sgp, cpu))->ref))
5369                 *per_cpu_ptr(sdd->sgp, cpu) = NULL;
5370 }
5371 
5372 #ifdef CONFIG_SCHED_SMT
5373 static const struct cpumask *cpu_smt_mask(int cpu)
5374 {
5375         return topology_thread_cpumask(cpu);
5376 }
5377 #endif
5378 
5379 /*
5380  * Topology list, bottom-up.
5381  */
5382 static struct sched_domain_topology_level default_topology[] = {
5383 #ifdef CONFIG_SCHED_SMT
5384         { sd_init_SIBLING, cpu_smt_mask, },
5385 #endif
5386 #ifdef CONFIG_SCHED_MC
5387         { sd_init_MC, cpu_coregroup_mask, },
5388 #endif
5389 #ifdef CONFIG_SCHED_BOOK
5390         { sd_init_BOOK, cpu_book_mask, },
5391 #endif
5392         { sd_init_CPU, cpu_cpu_mask, },
5393         { NULL, },
5394 };
5395 
5396 static struct sched_domain_topology_level *sched_domain_topology = default_topology;
5397 
5398 #define for_each_sd_topology(tl)                        \
5399         for (tl = sched_domain_topology; tl->init; tl++)
5400 
5401 #ifdef CONFIG_NUMA
5402 
5403 static int sched_domains_numa_levels;
5404 static int *sched_domains_numa_distance;
5405 static struct cpumask ***sched_domains_numa_masks;
5406 static int sched_domains_curr_level;
5407 
5408 static inline int sd_local_flags(int level)
5409 {
5410         if (sched_domains_numa_distance[level] > RECLAIM_DISTANCE)
5411                 return 0;
5412 
5413         return SD_BALANCE_EXEC | SD_BALANCE_FORK | SD_WAKE_AFFINE;
5414 }
5415 
5416 static struct sched_domain *
5417 sd_numa_init(struct sched_domain_topology_level *tl, int cpu)
5418 {
5419         struct sched_domain *sd = *per_cpu_ptr(tl->data.sd, cpu);
5420         int level = tl->numa_level;
5421         int sd_weight = cpumask_weight(
5422                         sched_domains_numa_masks[level][cpu_to_node(cpu)]);
5423 
5424         *sd = (struct sched_domain){
5425                 .min_interval           = sd_weight,
5426                 .max_interval           = 2*sd_weight,
5427                 .busy_factor            = 32,
5428                 .imbalance_pct          = 125,
5429                 .cache_nice_tries       = 2,
5430                 .busy_idx               = 3,
5431                 .idle_idx               = 2,
5432                 .newidle_idx            = 0,
5433                 .wake_idx               = 0,
5434                 .forkexec_idx           = 0,
5435 
5436                 .flags                  = 1*SD_LOAD_BALANCE
5437                                         | 1*SD_BALANCE_NEWIDLE
5438                                         | 0*SD_BALANCE_EXEC
5439                                         | 0*SD_BALANCE_FORK
5440                                         | 0*SD_BALANCE_WAKE
5441                                         | 0*SD_WAKE_AFFINE
5442                                         | 0*SD_SHARE_CPUPOWER
5443                                         | 0*SD_SHARE_PKG_RESOURCES
5444                                         | 1*SD_SERIALIZE
5445                                         | 0*SD_PREFER_SIBLING
5446                                         | 1*SD_NUMA
5447                                         | sd_local_flags(level)
5448                                         ,
5449                 .last_balance           = jiffies,
5450                 .balance_interval       = sd_weight,
5451         };
5452         SD_INIT_NAME(sd, NUMA);
5453         sd->private = &tl->data;
5454 
5455         /*
5456          * Ugly hack to pass state to sd_numa_mask()...
5457          */
5458         sched_domains_curr_level = tl->numa_level;
5459 
5460         return sd;
5461 }
5462 
5463 static const struct cpumask *sd_numa_mask(int cpu)
5464 {
5465         return sched_domains_numa_masks[sched_domains_curr_level][cpu_to_node(cpu)];
5466 }
5467 
5468 static void sched_numa_warn(const char *str)
5469 {
5470         static int done = false;
5471         int i,j;
5472 
5473         if (done)
5474                 return;
5475 
5476         done = true;
5477 
5478         printk(KERN_WARNING "ERROR: %s\n\n", str);
5479 
5480         for (i = 0; i < nr_node_ids; i++) {
5481                 printk(KERN_WARNING "  ");
5482                 for (j = 0; j < nr_node_ids; j++)
5483                         printk(KERN_CONT "%02d ", node_distance(i,j));
5484                 printk(KERN_CONT "\n");
5485         }
5486         printk(KERN_WARNING "\n");
5487 }
5488 
5489 static bool find_numa_distance(int distance)
5490 {
5491         int i;
5492 
5493         if (distance == node_distance(0, 0))
5494                 return true;
5495 
5496         for (i = 0; i < sched_domains_numa_levels; i++) {
5497                 if (sched_domains_numa_distance[i] == distance)
5498                         return true;
5499         }
5500 
5501         return false;
5502 }
5503 
5504 static void sched_init_numa(void)
5505 {
5506         int next_distance, curr_distance = node_distance(0, 0);
5507         struct sched_domain_topology_level *tl;
5508         int level = 0;
5509         int i, j, k;
5510 
5511         sched_domains_numa_distance = kzalloc(sizeof(int) * nr_node_ids, GFP_KERNEL);
5512         if (!sched_domains_numa_distance)
5513                 return;
5514 
5515         /*
5516          * O(nr_nodes^2) deduplicating selection sort -- in order to find the
5517          * unique distances in the node_distance() table.
5518          *
5519          * Assumes node_distance(0,j) includes all distances in
5520          * node_distance(i,j) in order to avoid cubic time.
5521          */
5522         next_distance = curr_distance;
5523         for (i = 0; i < nr_node_ids; i++) {
5524                 for (j = 0; j < nr_node_ids; j++) {
5525                         for (k = 0; k < nr_node_ids; k++) {
5526                                 int distance = node_distance(i, k);
5527 
5528                                 if (distance > curr_distance &&
5529                                     (distance < next_distance ||
5530                                      next_distance == curr_distance))
5531                                         next_distance = distance;
5532 
5533                                 /*
5534                                  * While not a strong assumption it would be nice to know
5535                                  * about cases where if node A is connected to B, B is not
5536                                  * equally connected to A.
5537                                  */
5538                                 if (sched_debug() && node_distance(k, i) != distance)
5539                                         sched_numa_warn("Node-distance not symmetric");
5540 
5541                                 if (sched_debug() && i && !find_numa_distance(distance))
5542                                         sched_numa_warn("Node-0 not representative");
5543                         }
5544                         if (next_distance != curr_distance) {
5545                                 sched_domains_numa_distance[level++] = next_distance;
5546                                 sched_domains_numa_levels = level;
5547                                 curr_distance = next_distance;
5548                         } else break;
5549                 }
5550 
5551                 /*
5552                  * In case of sched_debug() we verify the above assumption.
5553                  */
5554                 if (!sched_debug())
5555                         break;
5556         }
5557         /*
5558          * 'level' contains the number of unique distances, excluding the
5559          * identity distance node_distance(i,i).
5560          *
5561          * The sched_domains_numa_distance[] array includes the actual distance
5562          * numbers.
5563          */
5564 
5565         /*
5566          * Here, we should temporarily reset sched_domains_numa_levels to 0.
5567          * If it fails to allocate memory for array sched_domains_numa_masks[][],
5568          * the array will contain less then 'level' members. This could be
5569          * dangerous when we use it to iterate array sched_domains_numa_masks[][]
5570          * in other functions.
5571          *
5572          * We reset it to 'level' at the end of this function.
5573          */
5574         sched_domains_numa_levels = 0;
5575 
5576         sched_domains_numa_masks = kzalloc(sizeof(void *) * level, GFP_KERNEL);
5577         if (!sched_domains_numa_masks)
5578                 return;
5579 
5580         /*
5581          * Now for each level, construct a mask per node which contains all
5582          * cpus of nodes that are that many hops away from us.
5583          */
5584         for (i = 0; i < level; i++) {
5585                 sched_domains_numa_masks[i] =
5586                         kzalloc(nr_node_ids * sizeof(void *), GFP_KERNEL);
5587                 if (!sched_domains_numa_masks[i])
5588                         return;
5589 
5590                 for (j = 0; j < nr_node_ids; j++) {
5591                         struct cpumask *mask = kzalloc(cpumask_size(), GFP_KERNEL);
5592                         if (!mask)
5593                                 return;
5594 
5595                         sched_domains_numa_masks[i][j] = mask;
5596 
5597                         for (k = 0; k < nr_node_ids; k++) {
5598                                 if (node_distance(j, k) > sched_domains_numa_distance[i])
5599                                         continue;
5600 
5601                                 cpumask_or(mask, mask, cpumask_of_node(k));
5602                         }
5603                 }
5604         }
5605 
5606         tl = kzalloc((ARRAY_SIZE(default_topology) + level) *
5607                         sizeof(struct sched_domain_topology_level), GFP_KERNEL);
5608         if (!tl)
5609                 return;
5610 
5611         /*
5612          * Copy the default topology bits..
5613          */
5614         for (i = 0; default_topology[i].init; i++)
5615                 tl[i] = default_topology[i];
5616 
5617         /*
5618          * .. and append 'j' levels of NUMA goodness.
5619          */
5620         for (j = 0; j < level; i++, j++) {
5621                 tl[i] = (struct sched_domain_topology_level){
5622                         .init = sd_numa_init,
5623                         .mask = sd_numa_mask,
5624                         .flags = SDTL_OVERLAP,
5625                         .numa_level = j,
5626                 };
5627         }
5628 
5629         sched_domain_topology = tl;
5630 
5631         sched_domains_numa_levels = level;
5632 }
5633 
5634 static void sched_domains_numa_masks_set(int cpu)
5635 {
5636         int i, j;
5637         int node = cpu_to_node(cpu);
5638 
5639         for (i = 0; i < sched_domains_numa_levels; i++) {
5640                 for (j = 0; j < nr_node_ids; j++) {
5641                         if (node_distance(j, node) <= sched_domains_numa_distance[i])
5642                                 cpumask_set_cpu(cpu, sched_domains_numa_masks[i][j]);
5643                 }
5644         }
5645 }
5646 
5647 static void sched_domains_numa_masks_clear(int cpu)
5648 {
5649         int i, j;
5650         for (i = 0; i < sched_domains_numa_levels; i++) {
5651                 for (j = 0; j < nr_node_ids; j++)
5652                         cpumask_clear_cpu(cpu, sched_domains_numa_masks[i][j]);
5653         }
5654 }
5655 
5656 /*
5657  * Update sched_domains_numa_masks[level][node] array when new cpus
5658  * are onlined.
5659  */
5660 static int sched_domains_numa_masks_update(struct notifier_block *nfb,
5661                                            unsigned long action,
5662                                            void *hcpu)
5663 {
5664         int cpu = (long)hcpu;
5665 
5666         switch (action & ~CPU_TASKS_FROZEN) {
5667         case CPU_ONLINE:
5668                 sched_domains_numa_masks_set(cpu);
5669                 break;
5670 
5671         case CPU_DEAD:
5672                 sched_domains_numa_masks_clear(cpu);
5673                 break;
5674 
5675         default:
5676                 return NOTIFY_DONE;
5677         }
5678 
5679         return NOTIFY_OK;
5680 }
5681 #else
5682 static inline void sched_init_numa(void)
5683 {
5684 }
5685 
5686 static int sched_domains_numa_masks_update(struct notifier_block *nfb,
5687                                            unsigned long action,
5688                                            void *hcpu)
5689 {
5690         return 0;
5691 }
5692 #endif /* CONFIG_NUMA */
5693 
5694 static int __sdt_alloc(const struct cpumask *cpu_map)
5695 {
5696         struct sched_domain_topology_level *tl;
5697         int j;
5698 
5699         for_each_sd_topology(tl) {
5700                 struct sd_data *sdd = &tl->data;
5701 
5702                 sdd->sd = alloc_percpu(struct sched_domain *);
5703                 if (!sdd->sd)
5704                         return -ENOMEM;
5705 
5706                 sdd->sg = alloc_percpu(struct sched_group *);
5707                 if (!sdd->sg)
5708                         return -ENOMEM;
5709 
5710                 sdd->sgp = alloc_percpu(struct sched_group_power *);
5711                 if (!sdd->sgp)
5712                         return -ENOMEM;
5713 
5714                 for_each_cpu(j, cpu_map) {
5715                         struct sched_domain *sd;
5716                         struct sched_group *sg;
5717                         struct sched_group_power *sgp;
5718 
5719                         sd = kzalloc_node(sizeof(struct sched_domain) + cpumask_size(),
5720                                         GFP_KERNEL, cpu_to_node(j));
5721                         if (!sd)
5722                                 return -ENOMEM;
5723 
5724                         *per_cpu_ptr(sdd->sd, j) = sd;
5725 
5726                         sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
5727                                         GFP_KERNEL, cpu_to_node(j));
5728                         if (!sg)
5729                                 return -ENOMEM;
5730 
5731                         sg->next = sg;
5732 
5733                         *per_cpu_ptr(sdd->sg, j) = sg;
5734 
5735                         sgp = kzalloc_node(sizeof(struct sched_group_power) + cpumask_size(),
5736                                         GFP_KERNEL, cpu_to_node(j));
5737                         if (!sgp)
5738                                 return -ENOMEM;
5739 
5740                         *per_cpu_ptr(sdd->sgp, j) = sgp;
5741                 }
5742         }
5743 
5744         return 0;
5745 }
5746 
5747 static void __sdt_free(const struct cpumask *cpu_map)
5748 {
5749         struct sched_domain_topology_level *tl;
5750         int j;
5751 
5752         for_each_sd_topology(tl) {
5753                 struct sd_data *sdd = &tl->data;
5754 
5755                 for_each_cpu(j, cpu_map) {
5756                         struct sched_domain *sd;
5757 
5758                         if (sdd->sd) {
5759                                 sd = *per_cpu_ptr(sdd->sd, j);
5760                                 if (sd && (sd->flags & SD_OVERLAP))
5761                                         free_sched_groups(sd->groups, 0);
5762                                 kfree(*per_cpu_ptr(sdd->sd, j));
5763                         }
5764 
5765                         if (sdd->sg)
5766                                 kfree(*per_cpu_ptr(sdd->sg, j));
5767                         if (sdd->sgp)
5768                                 kfree(*per_cpu_ptr(sdd->sgp, j));
5769                 }
5770                 free_percpu(sdd->sd);
5771                 sdd->sd = NULL;
5772                 free_percpu(sdd->sg);
5773                 sdd->sg = NULL;
5774                 free_percpu(sdd->sgp);
5775                 sdd->sgp = NULL;
5776         }
5777 }
5778 
5779 struct sched_domain *build_sched_domain(struct sched_domain_topology_level *tl,
5780                 const struct cpumask *cpu_map, struct sched_domain_attr *attr,
5781                 struct sched_domain *child, int cpu)
5782 {
5783         struct sched_domain *sd = tl->init(tl, cpu);
5784         if (!sd)
5785                 return child;
5786 
5787         cpumask_and(sched_domain_span(sd), cpu_map, tl->mask(cpu));
5788         if (child) {
5789                 sd->level = child->level + 1;
5790                 sched_domain_level_max = max(sched_domain_level_max, sd->level);
5791                 child->parent = sd;
5792                 sd->child = child;
5793         }
5794         set_domain_attribute(sd, attr);
5795 
5796         return sd;
5797 }
5798 
5799 /*
5800  * Build sched domains for a given set of cpus and attach the sched domains
5801  * to the individual cpus
5802  */
5803 static int build_sched_domains(const struct cpumask *cpu_map,
5804                                struct sched_domain_attr *attr)
5805 {
5806         enum s_alloc alloc_state;
5807         struct sched_domain *sd;
5808         struct s_data d;
5809         int i, ret = -ENOMEM;
5810 
5811         alloc_state = __visit_domain_allocation_hell(&d, cpu_map);
5812         if (alloc_state != sa_rootdomain)
5813                 goto error;
5814 
5815         /* Set up domains for cpus specified by the cpu_map. */
5816         for_each_cpu(i, cpu_map) {
5817                 struct sched_domain_topology_level *tl;
5818 
5819                 sd = NULL;
5820                 for_each_sd_topology(tl) {
5821                         sd = build_sched_domain(tl, cpu_map, attr, sd, i);
5822                         if (tl == sched_domain_topology)
5823                                 *per_cpu_ptr(d.sd, i) = sd;
5824                         if (tl->flags & SDTL_OVERLAP || sched_feat(FORCE_SD_OVERLAP))
5825                                 sd->flags |= SD_OVERLAP;
5826                         if (cpumask_equal(cpu_map, sched_domain_span(sd)))
5827                                 break;
5828                 }
5829         }
5830 
5831         /* Build the groups for the domains */
5832         for_each_cpu(i, cpu_map) {
5833                 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
5834                         sd->span_weight = cpumask_weight(sched_domain_span(sd));
5835                         if (sd->flags & SD_OVERLAP) {
5836                                 if (build_overlap_sched_groups(sd, i))
5837                                         goto error;
5838                         } else {
5839                                 if (build_sched_groups(sd, i))
5840                                         goto error;
5841                         }
5842                 }
5843         }
5844 
5845         /* Calculate CPU power for physical packages and nodes */
5846         for (i = nr_cpumask_bits-1; i >= 0; i--) {
5847                 if (!cpumask_test_cpu(i, cpu_map))
5848                         continue;
5849 
5850                 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
5851                         claim_allocations(i, sd);
5852                         init_sched_groups_power(i, sd);
5853                 }
5854         }
5855 
5856         /* Attach the domains */
5857         rcu_read_lock();
5858         for_each_cpu(i, cpu_map) {
5859                 sd = *per_cpu_ptr(d.sd, i);
5860                 cpu_attach_domain(sd, d.rd, i);
5861         }
5862         rcu_read_unlock();
5863 
5864         ret = 0;
5865 error:
5866         __free_domain_allocs(&d, alloc_state, cpu_map);
5867         return ret;
5868 }
5869 
5870 static cpumask_var_t *doms_cur; /* current sched domains */
5871 static int ndoms_cur;           /* number of sched domains in 'doms_cur' */
5872 static struct sched_domain_attr *dattr_cur;
5873                                 /* attribues of custom domains in 'doms_cur' */
5874 
5875 /*
5876  * Special case: If a kmalloc of a doms_cur partition (array of
5877  * cpumask) fails, then fallback to a single sched domain,
5878  * as determined by the single cpumask fallback_doms.
5879  */
5880 static cpumask_var_t fallback_doms;
5881 
5882 /*
5883  * arch_update_cpu_topology lets virtualized architectures update the
5884  * cpu core maps. It is supposed to return 1 if the topology changed
5885  * or 0 if it stayed the same.
5886  */
5887 int __attribute__((weak)) arch_update_cpu_topology(void)
5888 {
5889         return 0;
5890 }
5891 
5892 cpumask_var_t *alloc_sched_domains(unsigned int ndoms)
5893 {
5894         int i;
5895         cpumask_var_t *doms;
5896 
5897         doms = kmalloc(sizeof(*doms) * ndoms, GFP_KERNEL);
5898         if (!doms)
5899                 return NULL;
5900         for (i = 0; i < ndoms; i++) {
5901                 if (!alloc_cpumask_var(&doms[i], GFP_KERNEL)) {
5902                         free_sched_domains(doms, i);
5903                         return NULL;
5904                 }
5905         }
5906         return doms;
5907 }
5908 
5909 void free_sched_domains(cpumask_var_t doms[], unsigned int ndoms)
5910 {
5911         unsigned int i;
5912         for (i = 0; i < ndoms; i++)
5913                 free_cpumask_var(doms[i]);
5914         kfree(doms);
5915 }
5916 
5917 /*
5918  * Set up scheduler domains and groups. Callers must hold the hotplug lock.
5919  * For now this just excludes isolated cpus, but could be used to
5920  * exclude other special cases in the future.
5921  */
5922 static int init_sched_domains(const struct cpumask *cpu_map)
5923 {
5924         int err;
5925 
5926         arch_update_cpu_topology();
5927         ndoms_cur = 1;
5928         doms_cur = alloc_sched_domains(ndoms_cur);
5929         if (!doms_cur)
5930                 doms_cur = &fallback_doms;
5931         cpumask_andnot(doms_cur[0], cpu_map, cpu_isolated_map);
5932         err = build_sched_domains(doms_cur[0], NULL);
5933         register_sched_domain_sysctl();
5934 
5935         return err;
5936 }
5937 
5938 /*
5939  * Detach sched domains from a group of cpus specified in cpu_map
5940  * These cpus will now be attached to the NULL domain
5941  */
5942 static void detach_destroy_domains(const struct cpumask *cpu_map)
5943 {
5944         int i;
5945 
5946         rcu_read_lock();
5947         for_each_cpu(i, cpu_map)
5948                 cpu_attach_domain(NULL, &def_root_domain, i);
5949         rcu_read_unlock();
5950 }
5951 
5952 /* handle null as "default" */
5953 static int dattrs_equal(struct sched_domain_attr *cur, int idx_cur,
5954                         struct sched_domain_attr *new, int idx_new)
5955 {
5956         struct sched_domain_attr tmp;
5957 
5958         /* fast path */
5959         if (!new && !cur)
5960                 return 1;
5961 
5962         tmp = SD_ATTR_INIT;
5963         return !memcmp(cur ? (cur + idx_cur) : &tmp,
5964                         new ? (new + idx_new) : &tmp,
5965                         sizeof(struct sched_domain_attr));
5966 }
5967 
5968 /*
5969  * Partition sched domains as specified by the 'ndoms_new'
5970  * cpumasks in the array doms_new[] of cpumasks. This compares
5971  * doms_new[] to the current sched domain partitioning, doms_cur[].
5972  * It destroys each deleted domain and builds each new domain.
5973  *
5974  * 'doms_new' is an array of cpumask_var_t's of length 'ndoms_new'.
5975  * The masks don't intersect (don't overlap.) We should setup one
5976  * sched domain for each mask. CPUs not in any of the cpumasks will
5977  * not be load balanced. If the same cpumask appears both in the
5978  * current 'doms_cur' domains and in the new 'doms_new', we can leave
5979  * it as it is.
5980  *
5981  * The passed in 'doms_new' should be allocated using
5982  * alloc_sched_domains.  This routine takes ownership of it and will
5983  * free_sched_domains it when done with it. If the caller failed the
5984  * alloc call, then it can pass in doms_new == NULL && ndoms_new == 1,
5985  * and partition_sched_domains() will fallback to the single partition
5986  * 'fallback_doms', it also forces the domains to be rebuilt.
5987  *
5988  * If doms_new == NULL it will be replaced with cpu_online_mask.
5989  * ndoms_new == 0 is a special case for destroying existing domains,
5990  * and it will not create the default domain.
5991  *
5992  * Call with hotplug lock held
5993  */
5994 void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
5995                              struct sched_domain_attr *dattr_new)
5996 {
5997         int i, j, n;
5998         int new_topology;
5999 
6000         mutex_lock(&sched_domains_mutex);
6001 
6002         /* always unregister in case we don't destroy any domains */
6003         unregister_sched_domain_sysctl();
6004 
6005         /* Let architecture update cpu core mappings. */
6006         new_topology = arch_update_cpu_topology();
6007 
6008         n = doms_new ? ndoms_new : 0;
6009 
6010         /* Destroy deleted domains */
6011         for (i = 0; i < ndoms_cur; i++) {
6012                 for (j = 0; j < n && !new_topology; j++) {
6013                         if (cpumask_equal(doms_cur[i], doms_new[j])
6014                             && dattrs_equal(dattr_cur, i, dattr_new, j))
6015                                 goto match1;
6016                 }
6017                 /* no match - a current sched domain not in new doms_new[] */
6018                 detach_destroy_domains(doms_cur[i]);
6019 match1:
6020                 ;
6021         }
6022 
6023         n = ndoms_cur;
6024         if (doms_new == NULL) {
6025                 n = 0;
6026                 doms_new = &fallback_doms;
6027                 cpumask_andnot(doms_new[0], cpu_active_mask, cpu_isolated_map);
6028                 WARN_ON_ONCE(dattr_new);
6029         }
6030 
6031         /* Build new domains */
6032         for (i = 0; i < ndoms_new; i++) {
6033                 for (j = 0; j < n && !new_topology; j++) {
6034                         if (cpumask_equal(doms_new[i], doms_cur[j])
6035                             && dattrs_equal(dattr_new, i, dattr_cur, j))
6036                                 goto match2;
6037                 }
6038                 /* no match - add a new doms_new */
6039                 build_sched_domains(doms_new[i], dattr_new ? dattr_new + i : NULL);
6040 match2:
6041                 ;
6042         }
6043 
6044         /* Remember the new sched domains */
6045         if (doms_cur != &fallback_doms)
6046                 free_sched_domains(doms_cur, ndoms_cur);
6047         kfree(dattr_cur);       /* kfree(NULL) is safe */
6048         doms_cur = doms_new;
6049         dattr_cur = dattr_new;
6050         ndoms_cur = ndoms_new;
6051 
6052         register_sched_domain_sysctl();
6053 
6054         mutex_unlock(&sched_domains_mutex);
6055 }
6056 
6057 static int num_cpus_frozen;     /* used to mark begin/end of suspend/resume */
6058 
6059 /*
6060  * Update cpusets according to cpu_active mask.  If cpusets are
6061  * disabled, cpuset_update_active_cpus() becomes a simple wrapper
6062  * around partition_sched_domains().
6063  *
6064  * If we come here as part of a suspend/resume, don't touch cpusets because we
6065  * want to restore it back to its original state upon resume anyway.
6066  */
6067 static int cpuset_cpu_active(struct notifier_block *nfb, unsigned long action,
6068                              void *hcpu)
6069 {
6070         switch (action) {
6071         case CPU_ONLINE_FROZEN:
6072         case CPU_DOWN_FAILED_FROZEN:
6073 
6074                 /*
6075                  * num_cpus_frozen tracks how many CPUs are involved in suspend
6076                  * resume sequence. As long as this is not the last online
6077                  * operation in the resume sequence, just build a single sched
6078                  * domain, ignoring cpusets.
6079                  */
6080                 num_cpus_frozen--;
6081                 if (likely(num_cpus_frozen)) {
6082                         partition_sched_domains(1, NULL, NULL);
6083                         break;
6084                 }
6085 
6086                 /*
6087                  * This is the last CPU online operation. So fall through and
6088                  * restore the original sched domains by considering the
6089                  * cpuset configurations.
6090                  */
6091 
6092         case CPU_ONLINE:
6093         case CPU_DOWN_FAILED:
6094                 cpuset_update_active_cpus(true);
6095                 break;
6096         default:
6097                 return NOTIFY_DONE;
6098         }
6099         return NOTIFY_OK;
6100 }
6101 
6102 static int cpuset_cpu_inactive(struct notifier_block *nfb, unsigned long action,
6103                                void *hcpu)
6104 {
6105         switch (action) {
6106         case CPU_DOWN_PREPARE:
6107                 cpuset_update_active_cpus(false);
6108                 break;
6109         case CPU_DOWN_PREPARE_FROZEN:
6110                 num_cpus_frozen++;
6111                 partition_sched_domains(1, NULL, NULL);
6112                 break;
6113         default:
6114                 return NOTIFY_DONE;
6115         }
6116         return NOTIFY_OK;
6117 }
6118 
6119 void __init sched_init_smp(void)
6120 {
6121         cpumask_var_t non_isolated_cpus;
6122 
6123         alloc_cpumask_var(&non_isolated_cpus, GFP_KERNEL);
6124         alloc_cpumask_var(&fallback_doms, GFP_KERNEL);
6125 
6126         sched_init_numa();
6127 
6128         /*
6129          * There's no userspace yet to cause hotplug operations; hence all the
6130          * cpu masks are stable and all blatant races in the below code cannot
6131          * happen.
6132          */
6133         mutex_lock(&sched_domains_mutex);
6134         init_sched_domains(cpu_active_mask);
6135         cpumask_andnot(non_isolated_cpus, cpu_possible_mask, cpu_isolated_map);
6136         if (cpumask_empty(non_isolated_cpus))
6137                 cpumask_set_cpu(smp_processor_id(), non_isolated_cpus);
6138         mutex_unlock(&sched_domains_mutex);
6139 
6140         hotcpu_notifier(sched_domains_numa_masks_update, CPU_PRI_SCHED_ACTIVE);
6141         hotcpu_notifier(cpuset_cpu_active, CPU_PRI_CPUSET_ACTIVE);
6142         hotcpu_notifier(cpuset_cpu_inactive, CPU_PRI_CPUSET_INACTIVE);
6143 
6144         init_hrtick();
6145 
6146         /* Move init over to a non-isolated CPU */
6147         if (set_cpus_allowed_ptr(current, non_isolated_cpus) < 0)
6148                 BUG();
6149         sched_init_granularity();
6150         free_cpumask_var(non_isolated_cpus);
6151 
6152         init_sched_rt_class();
6153 }
6154 #else
6155 void __init sched_init_smp(void)
6156 {
6157         sched_init_granularity();
6158 }
6159 #endif /* CONFIG_SMP */
6160 
6161 const_debug unsigned int sysctl_timer_migration = 1;
6162 
6163 int in_sched_functions(unsigned long addr)
6164 {
6165         return in_lock_functions(addr) ||
6166                 (addr >= (unsigned long)__sched_text_start
6167                 && addr < (unsigned long)__sched_text_end);
6168 }
6169 
6170 #ifdef CONFIG_CGROUP_SCHED
6171 /*
6172  * Default task group.
6173  * Every task in system belongs to this group at bootup.
6174  */
6175 struct task_group root_task_group;
6176 LIST_HEAD(task_groups);
6177 #endif
6178 
6179 DECLARE_PER_CPU(cpumask_var_t, load_balance_mask);
6180 
6181 void __init sched_init(void)
6182 {
6183         int i, j;
6184         unsigned long alloc_size = 0, ptr;
6185 
6186 #ifdef CONFIG_FAIR_GROUP_SCHED
6187         alloc_size += 2 * nr_cpu_ids * sizeof(void **);
6188 #endif
6189 #ifdef CONFIG_RT_GROUP_SCHED
6190         alloc_size += 2 * nr_cpu_ids * sizeof(void **);
6191 #endif
6192 #ifdef CONFIG_CPUMASK_OFFSTACK
6193         alloc_size += num_possible_cpus() * cpumask_size();
6194 #endif
6195         if (alloc_size) {
6196                 ptr = (unsigned long)kzalloc(alloc_size, GFP_NOWAIT);
6197 
6198 #ifdef CONFIG_FAIR_GROUP_SCHED
6199                 root_task_group.se = (struct sched_entity **)ptr;
6200                 ptr += nr_cpu_ids * sizeof(void **);
6201 
6202                 root_task_group.cfs_rq = (struct cfs_rq **)ptr;
6203                 ptr += nr_cpu_ids * sizeof(void **);
6204 
6205 #endif /* CONFIG_FAIR_GROUP_SCHED */
6206 #ifdef CONFIG_RT_GROUP_SCHED
6207                 root_task_group.rt_se = (struct sched_rt_entity **)ptr;
6208                 ptr += nr_cpu_ids * sizeof(void **);
6209 
6210                 root_task_group.rt_rq = (struct rt_rq **)ptr;
6211                 ptr += nr_cpu_ids * sizeof(void **);
6212 
6213 #endif /* CONFIG_RT_GROUP_SCHED */
6214 #ifdef CONFIG_CPUMASK_OFFSTACK
6215                 for_each_possible_cpu(i) {
6216                         per_cpu(load_balance_mask, i) = (void *)ptr;
6217                         ptr += cpumask_size();
6218                 }
6219 #endif /* CONFIG_CPUMASK_OFFSTACK */
6220         }
6221 
6222 #ifdef CONFIG_SMP
6223         init_defrootdomain();
6224 #endif
6225 
6226         init_rt_bandwidth(&def_rt_bandwidth,
6227                         global_rt_period(), global_rt_runtime());
6228 
6229 #ifdef CONFIG_RT_GROUP_SCHED
6230         init_rt_bandwidth(&root_task_group.rt_bandwidth,
6231                         global_rt_period(), global_rt_runtime());
6232 #endif /* CONFIG_RT_GROUP_SCHED */
6233 
6234 #ifdef CONFIG_CGROUP_SCHED
6235         list_add(&root_task_group.list, &task_groups);
6236         INIT_LIST_HEAD(&root_task_group.children);
6237         INIT_LIST_HEAD(&root_task_group.siblings);
6238         autogroup_init(&init_task);
6239 
6240 #endif /* CONFIG_CGROUP_SCHED */
6241 
6242         for_each_possible_cpu(i) {
6243                 struct rq *rq;
6244 
6245                 rq = cpu_rq(i);
6246                 raw_spin_lock_init(&rq->lock);
6247                 rq->nr_running = 0;
6248                 rq->calc_load_active = 0;
6249                 rq->calc_load_update = jiffies + LOAD_FREQ;
6250                 init_cfs_rq(&rq->cfs);
6251                 init_rt_rq(&rq->rt, rq);
6252 #ifdef CONFIG_FAIR_GROUP_SCHED
6253                 root_task_group.shares = ROOT_TASK_GROUP_LOAD;
6254                 INIT_LIST_HEAD(&rq->leaf_cfs_rq_list);
6255                 /*
6256                  * How much cpu bandwidth does root_task_group get?
6257                  *
6258                  * In case of task-groups formed thr' the cgroup filesystem, it
6259                  * gets 100% of the cpu resources in the system. This overall
6260                  * system cpu resource is divided among the tasks of
6261                  * root_task_group and its child task-groups in a fair manner,
6262                  * based on each entity's (task or task-group's) weight
6263                  * (se->load.weight).
6264                  *
6265                  * In other words, if root_task_group has 10 tasks of weight
6266                  * 1024) and two child groups A0 and A1 (of weight 1024 each),
6267                  * then A0's share of the cpu resource is:
6268                  *
6269                  *      A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33%
6270                  *
6271                  * We achieve this by letting root_task_group's tasks sit
6272                  * directly in rq->cfs (i.e root_task_group->se[] = NULL).
6273                  */
6274                 init_cfs_bandwidth(&root_task_group.cfs_bandwidth);
6275                 init_tg_cfs_entry(&root_task_group, &rq->cfs, NULL, i, NULL);
6276 #endif /* CONFIG_FAIR_GROUP_SCHED */
6277 
6278                 rq->rt.rt_runtime = def_rt_bandwidth.rt_runtime;
6279 #ifdef CONFIG_RT_GROUP_SCHED
6280                 INIT_LIST_HEAD(&rq->leaf_rt_rq_list);
6281                 init_tg_rt_entry(&root_task_group, &rq->rt, NULL, i, NULL);
6282 #endif
6283 
6284                 for (j = 0; j < CPU_LOAD_IDX_MAX; j++)
6285                         rq->cpu_load[j] = 0;
6286 
6287                 rq->last_load_update_tick = jiffies;
6288 
6289 #ifdef CONFIG_SMP
6290                 rq->sd = NULL;
6291                 rq->rd = NULL;
6292                 rq->cpu_power = SCHED_POWER_SCALE;
6293                 rq->post_schedule = 0;
6294                 rq->active_balance = 0;
6295                 rq->next_balance = jiffies;
6296                 rq->push_cpu = 0;
6297                 rq->cpu = i;
6298                 rq->online = 0;
6299                 rq->idle_stamp = 0;
6300                 rq->avg_idle = 2*sysctl_sched_migration_cost;
6301                 rq->max_idle_balance_cost = sysctl_sched_migration_cost;
6302 
6303                 INIT_LIST_HEAD(&rq->cfs_tasks);
6304 
6305                 rq_attach_root(rq, &def_root_domain);
6306 #ifdef CONFIG_NO_HZ_COMMON
6307                 rq->nohz_flags = 0;
6308 #endif
6309 #ifdef CONFIG_NO_HZ_FULL
6310                 rq->last_sched_tick = 0;
6311 #endif
6312 #endif
6313                 init_rq_hrtick(rq);
6314                 atomic_set(&rq->nr_iowait, 0);
6315         }
6316 
6317         set_load_weight(&init_task);
6318 
6319 #ifdef CONFIG_PREEMPT_NOTIFIERS
6320         INIT_HLIST_HEAD(&init_task.preempt_notifiers);
6321 #endif
6322 
6323 #ifdef CONFIG_RT_MUTEXES
6324         plist_head_init(&init_task.pi_waiters);
6325 #endif
6326 
6327         /*
6328          * The boot idle thread does lazy MMU switching as well:
6329          */
6330         atomic_inc(&init_mm.mm_count);
6331         enter_lazy_tlb(&init_mm, current);
6332 
6333         /*
6334          * Make us the idle thread. Technically, schedule() should not be
6335          * called from this thread, however somewhere below it might be,
6336          * but because we are the idle thread, we just pick up running again
6337          * when this runqueue becomes "idle".
6338          */
6339         init_idle(current, smp_processor_id());
6340 
6341         calc_load_update = jiffies + LOAD_FREQ;
6342 
6343         /*
6344          * During early bootup we pretend to be a normal task:
6345          */
6346         current->sched_class = &fair_sched_class;
6347 
6348 #ifdef CONFIG_SMP
6349         zalloc_cpumask_var(&sched_domains_tmpmask, GFP_NOWAIT);
6350         /* May be allocated at isolcpus cmdline parse time */
6351         if (cpu_isolated_map == NULL)
6352                 zalloc_cpumask_var(&cpu_isolated_map, GFP_NOWAIT);
6353         idle_thread_set_boot_cpu();
6354 #endif
6355         init_sched_fair_class();
6356 
6357         scheduler_running = 1;
6358 }
6359 
6360 #ifdef CONFIG_DEBUG_ATOMIC_SLEEP
6361 static inline int preempt_count_equals(int preempt_offset)
6362 {
6363         int nested = (preempt_count() & ~PREEMPT_ACTIVE) + rcu_preempt_depth();
6364 
6365         return (nested == preempt_offset);
6366 }
6367 
6368 void __might_sleep(const char *file, int line, int preempt_offset)
6369 {
6370         static unsigned long prev_jiffy;        /* ratelimiting */
6371 
6372         rcu_sleep_check(); /* WARN_ON_ONCE() by default, no rate limit reqd. */
6373         if ((preempt_count_equals(preempt_offset) && !irqs_disabled()) ||
6374             system_state != SYSTEM_RUNNING || oops_in_progress)
6375                 return;
6376         if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
6377                 return;
6378         prev_jiffy = jiffies;
6379 
6380         printk(KERN_ERR
6381                 "BUG: sleeping function called from invalid context at %s:%d\n",
6382                         file, line);
6383         printk(KERN_ERR
6384                 "in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n",
6385                         in_atomic(), irqs_disabled(),
6386                         current->pid, current->comm);
6387 
6388         debug_show_held_locks(current);
6389         if (irqs_disabled())
6390                 print_irqtrace_events(current);
6391         dump_stack();
6392 }
6393 EXPORT_SYMBOL(__might_sleep);
6394 #endif
6395 
6396 #ifdef CONFIG_MAGIC_SYSRQ
6397 static void normalize_task(struct rq *rq, struct task_struct *p)
6398 {
6399         const struct sched_class *prev_class = p->sched_class;
6400         int old_prio = p->prio;
6401         int on_rq;
6402 
6403         on_rq = p->on_rq;
6404         if (on_rq)
6405                 dequeue_task(rq, p, 0);
6406         __setscheduler(rq, p, SCHED_NORMAL, 0);
6407         if (on_rq) {
6408                 enqueue_task(rq, p, 0);
6409                 resched_task(rq->curr);
6410         }
6411 
6412         check_class_changed(rq, p, prev_class, old_prio);
6413 }
6414 
6415 void normalize_rt_tasks(void)
6416 {
6417         struct task_struct *g, *p;
6418         unsigned long flags;
6419         struct rq *rq;
6420 
6421         read_lock_irqsave(&tasklist_lock, flags);
6422         do_each_thread(g, p) {
6423                 /*
6424                  * Only normalize user tasks:
6425                  */
6426                 if (!p->mm)
6427                         continue;
6428 
6429                 p->se.exec_start                = 0;
6430 #ifdef CONFIG_SCHEDSTATS
6431                 p->se.statistics.wait_start     = 0;
6432                 p->se.statistics.sleep_start    = 0;
6433                 p->se.statistics.block_start    = 0;
6434 #endif
6435 
6436                 if (!rt_task(p)) {
6437                         /*
6438                          * Renice negative nice level userspace
6439                          * tasks back to 0:
6440                          */
6441                         if (TASK_NICE(p) < 0 && p->mm)
6442                                 set_user_nice(p, 0);
6443                         continue;
6444                 }
6445 
6446                 raw_spin_lock(&p->pi_lock);
6447                 rq = __task_rq_lock(p);
6448 
6449                 normalize_task(rq, p);
6450 
6451                 __task_rq_unlock(rq);
6452                 raw_spin_unlock(&p->pi_lock);
6453         } while_each_thread(g, p);
6454 
6455         read_unlock_irqrestore(&tasklist_lock, flags);
6456 }
6457 
6458 #endif /* CONFIG_MAGIC_SYSRQ */
6459 
6460 #if defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB)
6461 /*
6462  * These functions are only useful for the IA64 MCA handling, or kdb.
6463  *
6464  * They can only be called when the whole system has been
6465  * stopped - every CPU needs to be quiescent, and no scheduling
6466  * activity can take place. Using them for anything else would
6467  * be a serious bug, and as a result, they aren't even visible
6468  * under any other configuration.
6469  */
6470 
6471 /**
6472  * curr_task - return the current task for a given cpu.
6473  * @cpu: the processor in question.
6474  *
6475  * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
6476  *
6477  * Return: The current task for @cpu.
6478  */
6479 struct task_struct *curr_task(int cpu)
6480 {
6481         return cpu_curr(cpu);
6482 }
6483 
6484 #endif /* defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) */
6485 
6486 #ifdef CONFIG_IA64
6487 /**
6488  * set_curr_task - set the current task for a given cpu.
6489  * @cpu: the processor in question.
6490  * @p: the task pointer to set.
6491  *
6492  * Description: This function must only be used when non-maskable interrupts
6493  * are serviced on a separate stack. It allows the architecture to switch the
6494  * notion of the current task on a cpu in a non-blocking manner. This function
6495  * must be called with all CPU's synchronized, and interrupts disabled, the
6496  * and caller must save the original value of the current task (see
6497  * curr_task() above) and restore that value before reenabling interrupts and
6498  * re-starting the system.
6499  *
6500  * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
6501  */
6502 void set_curr_task(int cpu, struct task_struct *p)
6503 {
6504         cpu_curr(cpu) = p;
6505 }
6506 
6507 #endif
6508 
6509 #ifdef CONFIG_CGROUP_SCHED
6510 /* task_group_lock serializes the addition/removal of task groups */
6511 static DEFINE_SPINLOCK(task_group_lock);
6512 
6513 static void free_sched_group(struct task_group *tg)
6514 {
6515         free_fair_sched_group(tg);
6516         free_rt_sched_group(tg);
6517         autogroup_free(tg);
6518         kfree(tg);
6519 }
6520 
6521 /* allocate runqueue etc for a new task group */
6522 struct task_group *sched_create_group(struct task_group *parent)
6523 {
6524         struct task_group *tg;
6525 
6526         tg = kzalloc(sizeof(*tg), GFP_KERNEL);
6527         if (!tg)
6528                 return ERR_PTR(-ENOMEM);
6529 
6530         if (!alloc_fair_sched_group(tg, parent))
6531                 goto err;
6532 
6533         if (!alloc_rt_sched_group(tg, parent))
6534                 goto err;
6535 
6536         return tg;
6537 
6538 err:
6539         free_sched_group(tg);
6540         return ERR_PTR(-ENOMEM);
6541 }
6542 
6543 void sched_online_group(struct task_group *tg, struct task_group *parent)
6544 {
6545         unsigned long flags;
6546 
6547         spin_lock_irqsave(&task_group_lock, flags);
6548         list_add_rcu(&tg->list, &task_groups);
6549 
6550         WARN_ON(!parent); /* root should already exist */
6551 
6552         tg->parent = parent;
6553         INIT_LIST_HEAD(&tg->children);
6554         list_add_rcu(&tg->siblings, &parent->children);
6555         spin_unlock_irqrestore(&task_group_lock, flags);
6556 }
6557 
6558 /* rcu callback to free various structures associated with a task group */
6559 static void free_sched_group_rcu(struct rcu_head *rhp)
6560 {
6561         /* now it should be safe to free those cfs_rqs */
6562         free_sched_group(container_of(rhp, struct task_group, rcu));
6563 }
6564 
6565 /* Destroy runqueue etc associated with a task group */
6566 void sched_destroy_group(struct task_group *tg)
6567 {
6568         /* wait for possible concurrent references to cfs_rqs complete */
6569         call_rcu(&tg->rcu, free_sched_group_rcu);
6570 }
6571 
6572 void sched_offline_group(struct task_group *tg)
6573 {
6574         unsigned long flags;
6575         int i;
6576 
6577         /* end participation in shares distribution */
6578         for_each_possible_cpu(i)
6579                 unregister_fair_sched_group(tg, i);
6580 
6581         spin_lock_irqsave(&task_group_lock, flags);
6582         list_del_rcu(&tg->list);
6583         list_del_rcu(&tg->siblings);
6584         spin_unlock_irqrestore(&task_group_lock, flags);
6585 }
6586 
6587 /* change task's runqueue when it moves between groups.
6588  *      The caller of this function should have put the task in its new group
6589  *      by now. This function just updates tsk->se.cfs_rq and tsk->se.parent to
6590  *      reflect its new group.
6591  */
6592 void sched_move_task(struct task_struct *tsk)
6593 {
6594         struct task_group *tg;
6595         int on_rq, running;
6596         unsigned long flags;
6597         struct rq *rq;
6598 
6599         rq = task_rq_lock(tsk, &flags);
6600 
6601         running = task_current(rq, tsk);
6602         on_rq = tsk->on_rq;
6603 
6604         if (on_rq)
6605                 dequeue_task(rq, tsk, 0);
6606         if (unlikely(running))
6607                 tsk->sched_class->put_prev_task(rq, tsk);
6608 
6609         tg = container_of(task_css_check(tsk, cpu_cgroup_subsys_id,
6610                                 lockdep_is_held(&tsk->sighand->siglock)),
6611                           struct task_group, css);
6612         tg = autogroup_task_group(tsk, tg);
6613         tsk->sched_task_group = tg;
6614 
6615 #ifdef CONFIG_FAIR_GROUP_SCHED
6616         if (tsk->sched_class->task_move_group)
6617                 tsk->sched_class->task_move_group(tsk, on_rq);
6618         else
6619 #endif
6620                 set_task_rq(tsk, task_cpu(tsk));
6621 
6622         if (unlikely(running))
6623                 tsk->sched_class->set_curr_task(rq);
6624         if (on_rq)
6625                 enqueue_task(rq, tsk, 0);
6626 
6627         task_rq_unlock(rq, tsk, &flags);
6628 }
6629 #endif /* CONFIG_CGROUP_SCHED */
6630 
6631 #if defined(CONFIG_RT_GROUP_SCHED) || defined(CONFIG_CFS_BANDWIDTH)
6632 static unsigned long to_ratio(u64 period, u64 runtime)
6633 {
6634         if (runtime == RUNTIME_INF)
6635                 return 1ULL << 20;
6636 
6637         return div64_u64(runtime << 20, period);
6638 }
6639 #endif
6640 
6641 #ifdef CONFIG_RT_GROUP_SCHED
6642 /*
6643  * Ensure that the real time constraints are schedulable.
6644  */
6645 static DEFINE_MUTEX(rt_constraints_mutex);
6646 
6647 /* Must be called with tasklist_lock held */
6648 static inline int tg_has_rt_tasks(struct task_group *tg)
6649 {
6650         struct task_struct *g, *p;
6651 
6652         do_each_thread(g, p) {
6653                 if (rt_task(p) && task_rq(p)->rt.tg == tg)
6654                         return 1;
6655         } while_each_thread(g, p);
6656 
6657         return 0;
6658 }
6659 
6660 struct rt_schedulable_data {
6661         struct task_group *tg;
6662         u64 rt_period;
6663         u64 rt_runtime;
6664 };
6665 
6666 static int tg_rt_schedulable(struct task_group *tg, void *data)
6667 {
6668         struct rt_schedulable_data *d = data;
6669         struct task_group *child;
6670         unsigned long total, sum = 0;
6671         u64 period, runtime;
6672 
6673         period = ktime_to_ns(tg->rt_bandwidth.rt_period);
6674         runtime = tg->rt_bandwidth.rt_runtime;
6675 
6676         if (tg == d->tg) {
6677                 period = d->rt_period;
6678                 runtime = d->rt_runtime;
6679         }
6680 
6681         /*
6682          * Cannot have more runtime than the period.
6683          */
6684         if (runtime > period && runtime != RUNTIME_INF)
6685                 return -EINVAL;
6686 
6687         /*
6688          * Ensure we don't starve existing RT tasks.
6689          */
6690         if (rt_bandwidth_enabled() && !runtime && tg_has_rt_tasks(tg))
6691                 return -EBUSY;
6692 
6693         total = to_ratio(period, runtime);
6694 
6695         /*
6696          * Nobody can have more than the global setting allows.
6697          */
6698         if (total > to_ratio(global_rt_period(), global_rt_runtime()))
6699                 return -EINVAL;
6700 
6701         /*
6702          * The sum of our children's runtime should not exceed our own.
6703          */
6704         list_for_each_entry_rcu(child, &tg->children, siblings) {
6705                 period = ktime_to_ns(child->rt_bandwidth.rt_period);
6706                 runtime = child->rt_bandwidth.rt_runtime;
6707 
6708                 if (child == d->tg) {
6709                         period = d->rt_period;
6710                         runtime = d->rt_runtime;
6711                 }
6712 
6713                 sum += to_ratio(period, runtime);
6714         }
6715 
6716         if (sum > total)
6717                 return -EINVAL;
6718 
6719         return 0;
6720 }
6721 
6722 static int __rt_schedulable(struct task_group *tg, u64 period, u64 runtime)
6723 {
6724         int ret;
6725 
6726         struct rt_schedulable_data data = {
6727                 .tg = tg,
6728                 .rt_period = period,
6729                 .rt_runtime = runtime,
6730         };
6731 
6732         rcu_read_lock();
6733         ret = walk_tg_tree(tg_rt_schedulable, tg_nop, &data);
6734         rcu_read_unlock();
6735 
6736         return ret;
6737 }
6738 
6739 static int tg_set_rt_bandwidth(struct task_group *tg,
6740                 u64 rt_period, u64 rt_runtime)
6741 {
6742         int i, err = 0;
6743 
6744         mutex_lock(&rt_constraints_mutex);
6745         read_lock(&tasklist_lock);
6746         err = __rt_schedulable(tg, rt_period, rt_runtime);
6747         if (err)
6748                 goto unlock;
6749 
6750         raw_spin_lock_irq(&tg->rt_bandwidth.rt_runtime_lock);
6751         tg->rt_bandwidth.rt_period = ns_to_ktime(rt_period);
6752         tg->rt_bandwidth.rt_runtime = rt_runtime;
6753 
6754         for_each_possible_cpu(i) {
6755                 struct rt_rq *rt_rq = tg->rt_rq[i];
6756 
6757                 raw_spin_lock(&rt_rq->rt_runtime_lock);
6758                 rt_rq->rt_runtime = rt_runtime;
6759                 raw_spin_unlock(&rt_rq->rt_runtime_lock);
6760         }
6761         raw_spin_unlock_irq(&tg->rt_bandwidth.rt_runtime_lock);
6762 unlock:
6763         read_unlock(&tasklist_lock);
6764         mutex_unlock(&rt_constraints_mutex);
6765 
6766         return err;
6767 }
6768 
6769 static int sched_group_set_rt_runtime(struct task_group *tg, long rt_runtime_us)
6770 {
6771         u64 rt_runtime, rt_period;
6772 
6773         rt_period = ktime_to_ns(tg->rt_bandwidth.rt_period);
6774         rt_runtime = (u64)rt_runtime_us * NSEC_PER_USEC;
6775         if (rt_runtime_us < 0)
6776                 rt_runtime = RUNTIME_INF;
6777 
6778         return tg_set_rt_bandwidth(tg, rt_period, rt_runtime);
6779 }
6780 
6781 static long sched_group_rt_runtime(struct task_group *tg)
6782 {
6783         u64 rt_runtime_us;
6784 
6785         if (tg->rt_bandwidth.rt_runtime == RUNTIME_INF)
6786                 return -1;
6787 
6788         rt_runtime_us = tg->rt_bandwidth.rt_runtime;
6789         do_div(rt_runtime_us, NSEC_PER_USEC);
6790         return rt_runtime_us;
6791 }
6792 
6793 static int sched_group_set_rt_period(struct task_group *tg, long rt_period_us)
6794 {
6795         u64 rt_runtime, rt_period;
6796 
6797         rt_period = (u64)rt_period_us * NSEC_PER_USEC;
6798         rt_runtime = tg->rt_bandwidth.rt_runtime;
6799 
6800         if (rt_period == 0)
6801                 return -EINVAL;
6802 
6803         return tg_set_rt_bandwidth(tg, rt_period, rt_runtime);
6804 }
6805 
6806 static long sched_group_rt_period(struct task_group *tg)
6807 {
6808         u64 rt_period_us;
6809 
6810         rt_period_us = ktime_to_ns(tg->rt_bandwidth.rt_period);
6811         do_div(rt_period_us, NSEC_PER_USEC);
6812         return rt_period_us;
6813 }
6814 
6815 static int sched_rt_global_constraints(void)
6816 {
6817         u64 runtime, period;
6818         int ret = 0;
6819 
6820         if (sysctl_sched_rt_period <= 0)
6821                 return -EINVAL;
6822 
6823         runtime = global_rt_runtime();
6824         period = global_rt_period();
6825 
6826         /*
6827          * Sanity check on the sysctl variables.
6828          */
6829         if (runtime > period && runtime != RUNTIME_INF)
6830                 return -EINVAL;
6831 
6832         mutex_lock(&rt_constraints_mutex);
6833         read_lock(&tasklist_lock);
6834         ret = __rt_schedulable(NULL, 0, 0);
6835         read_unlock(&tasklist_lock);
6836         mutex_unlock(&rt_constraints_mutex);
6837 
6838         return ret;
6839 }
6840 
6841 static int sched_rt_can_attach(struct task_group *tg, struct task_struct *tsk)
6842 {
6843         /* Don't accept realtime tasks when there is no way for them to run */
6844         if (rt_task(tsk) && tg->rt_bandwidth.rt_runtime == 0)
6845                 return 0;
6846 
6847         return 1;
6848 }
6849 
6850 #else /* !CONFIG_RT_GROUP_SCHED */
6851 static int sched_rt_global_constraints(void)
6852 {
6853         unsigned long flags;
6854         int i;
6855 
6856         if (sysctl_sched_rt_period <= 0)
6857                 return -EINVAL;
6858 
6859         /*
6860          * There's always some RT tasks in the root group
6861          * -- migration, kstopmachine etc..
6862          */
6863         if (sysctl_sched_rt_runtime == 0)
6864                 return -EBUSY;
6865 
6866         raw_spin_lock_irqsave(&def_rt_bandwidth.rt_runtime_lock, flags);
6867         for_each_possible_cpu(i) {
6868                 struct rt_rq *rt_rq = &cpu_rq(i)->rt;
6869 
6870                 raw_spin_lock(&rt_rq->rt_runtime_lock);
6871                 rt_rq->rt_runtime = global_rt_runtime();
6872                 raw_spin_unlock(&rt_rq->rt_runtime_lock);
6873         }
6874         raw_spin_unlock_irqrestore(&def_rt_bandwidth.rt_runtime_lock, flags);
6875 
6876         return 0;
6877 }
6878 #endif /* CONFIG_RT_GROUP_SCHED */
6879 
6880 int sched_rr_handler(struct ctl_table *table, int write,
6881                 void __user *buffer, size_t *lenp,
6882                 loff_t *ppos)
6883 {
6884         int ret;
6885         static DEFINE_MUTEX(mutex);
6886 
6887         mutex_lock(&mutex);
6888         ret = proc_dointvec(table, write, buffer, lenp, ppos);
6889         /* make sure that internally we keep jiffies */
6890         /* also, writing zero resets timeslice to default */
6891         if (!ret && write) {
6892                 sched_rr_timeslice = sched_rr_timeslice <= 0 ?
6893                         RR_TIMESLICE : msecs_to_jiffies(sched_rr_timeslice);
6894         }
6895         mutex_unlock(&mutex);
6896         return ret;
6897 }
6898 
6899 int sched_rt_handler(struct ctl_table *table, int write,
6900                 void __user *buffer, size_t *lenp,
6901                 loff_t *ppos)
6902 {
6903         int ret;
6904         int old_period, old_runtime;
6905         static DEFINE_MUTEX(mutex);
6906 
6907         mutex_lock(&mutex);
6908         old_period = sysctl_sched_rt_period;
6909         old_runtime = sysctl_sched_rt_runtime;
6910 
6911         ret = proc_dointvec(table, write, buffer, lenp, ppos);
6912 
6913         if (!ret && write) {
6914                 ret = sched_rt_global_constraints();
6915                 if (ret) {
6916                         sysctl_sched_rt_period = old_period;
6917                         sysctl_sched_rt_runtime = old_runtime;
6918                 } else {
6919                         def_rt_bandwidth.rt_runtime = global_rt_runtime();
6920                         def_rt_bandwidth.rt_period =
6921                                 ns_to_ktime(global_rt_period());
6922                 }
6923         }
6924         mutex_unlock(&mutex);
6925 
6926         return ret;
6927 }
6928 
6929 #ifdef CONFIG_CGROUP_SCHED
6930 
6931 static inline struct task_group *css_tg(struct cgroup_subsys_state *css)
6932 {
6933         return css ? container_of(css, struct task_group, css) : NULL;
6934 }
6935 
6936 static struct cgroup_subsys_state *
6937 cpu_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
6938 {
6939         struct task_group *parent = css_tg(parent_css);
6940         struct task_group *tg;
6941 
6942         if (!parent) {
6943                 /* This is early initialization for the top cgroup */
6944                 return &root_task_group.css;
6945         }
6946 
6947         tg = sched_create_group(parent);
6948         if (IS_ERR(tg))
6949                 return ERR_PTR(-ENOMEM);
6950 
6951         return &tg->css;
6952 }
6953 
6954 static int cpu_cgroup_css_online(struct cgroup_subsys_state *css)
6955 {
6956         struct task_group *tg = css_tg(css);
6957         struct task_group *parent = css_tg(css_parent(css));
6958 
6959         if (parent)
6960                 sched_online_group(tg, parent);
6961         return 0;
6962 }
6963 
6964 static void cpu_cgroup_css_free(struct cgroup_subsys_state *css)
6965 {
6966         struct task_group *tg = css_tg(css);
6967 
6968         sched_destroy_group(tg);
6969 }
6970 
6971 static void cpu_cgroup_css_offline(struct cgroup_subsys_state *css)
6972 {
6973         struct task_group *tg = css_tg(css);
6974 
6975         sched_offline_group(tg);
6976 }
6977 
6978 static int cpu_cgroup_can_attach(struct cgroup_subsys_state *css,
6979                                  struct cgroup_taskset *tset)
6980 {
6981         struct task_struct *task;
6982 
6983         cgroup_taskset_for_each(task, css, tset) {
6984 #ifdef CONFIG_RT_GROUP_SCHED
6985                 if (!sched_rt_can_attach(css_tg(css), task))
6986                         return -EINVAL;
6987 #else
6988                 /* We don't support RT-tasks being in separate groups */
6989                 if (task->sched_class != &fair_sched_class)
6990                         return -EINVAL;
6991 #endif
6992         }
6993         return 0;
6994 }
6995 
6996 static void cpu_cgroup_attach(struct cgroup_subsys_state *css,
6997                               struct cgroup_taskset *tset)
6998 {
6999         struct task_struct *task;
7000 
7001         cgroup_taskset_for_each(task, css, tset)
7002                 sched_move_task(task);
7003 }
7004 
7005 static void cpu_cgroup_exit(struct cgroup_subsys_state *css,
7006                             struct cgroup_subsys_state *old_css,
7007                             struct task_struct *task)
7008 {
7009         /*
7010          * cgroup_exit() is called in the copy_process() failure path.
7011          * Ignore this case since the task hasn't ran yet, this avoids
7012          * trying to poke a half freed task state from generic code.
7013          */
7014         if (!(task->flags & PF_EXITING))
7015                 return;
7016 
7017         sched_move_task(task);
7018 }
7019 
7020 #ifdef CONFIG_FAIR_GROUP_SCHED
7021 static int cpu_shares_write_u64(struct cgroup_subsys_state *css,
7022                                 struct cftype *cftype, u64 shareval)
7023 {
7024         return sched_group_set_shares(css_tg(css), scale_load(shareval));
7025 }
7026 
7027 static u64 cpu_shares_read_u64(struct cgroup_subsys_state *css,
7028                                struct cftype *cft)
7029 {
7030         struct task_group *tg = css_tg(css);
7031 
7032         return (u64) scale_load_down(tg->shares);
7033 }
7034 
7035 #ifdef CONFIG_CFS_BANDWIDTH
7036 static DEFINE_MUTEX(cfs_constraints_mutex);
7037 
7038 const u64 max_cfs_quota_period = 1 * NSEC_PER_SEC; /* 1s */
7039 const u64 min_cfs_quota_period = 1 * NSEC_PER_MSEC; /* 1ms */
7040 
7041 static int __cfs_schedulable(struct task_group *tg, u64 period, u64 runtime);
7042 
7043 static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota)
7044 {
7045         int i, ret = 0, runtime_enabled, runtime_was_enabled;
7046         struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
7047 
7048         if (tg == &root_task_group)
7049                 return -EINVAL;
7050 
7051         /*
7052          * Ensure we have at some amount of bandwidth every period.  This is
7053          * to prevent reaching a state of large arrears when throttled via
7054          * entity_tick() resulting in prolonged exit starvation.
7055          */
7056         if (quota < min_cfs_quota_period || period < min_cfs_quota_period)
7057                 return -EINVAL;
7058 
7059         /*
7060          * Likewise, bound things on the otherside by preventing insane quota
7061          * periods.  This also allows us to normalize in computing quota
7062          * feasibility.
7063          */
7064         if (period > max_cfs_quota_period)
7065                 return -EINVAL;
7066 
7067         mutex_lock(&cfs_constraints_mutex);
7068         ret = __cfs_schedulable(tg, period, quota);
7069         if (ret)
7070                 goto out_unlock;
7071 
7072         runtime_enabled = quota != RUNTIME_INF;
7073         runtime_was_enabled = cfs_b->quota != RUNTIME_INF;
7074         /*
7075          * If we need to toggle cfs_bandwidth_used, off->on must occur
7076          * before making related changes, and on->off must occur afterwards
7077          */
7078         if (runtime_enabled && !runtime_was_enabled)
7079                 cfs_bandwidth_usage_inc();
7080         raw_spin_lock_irq(&cfs_b->lock);
7081         cfs_b->period = ns_to_ktime(period);
7082         cfs_b->quota = quota;
7083 
7084         __refill_cfs_bandwidth_runtime(cfs_b);
7085         /* restart the period timer (if active) to handle new period expiry */
7086         if (runtime_enabled && cfs_b->timer_active) {
7087                 /* force a reprogram */
7088                 cfs_b->timer_active = 0;
7089                 __start_cfs_bandwidth(cfs_b);
7090         }
7091         raw_spin_unlock_irq(&cfs_b->lock);
7092 
7093         for_each_possible_cpu(i) {
7094                 struct cfs_rq *cfs_rq = tg->cfs_rq[i];
7095                 struct rq *rq = cfs_rq->rq;
7096 
7097                 raw_spin_lock_irq(&rq->lock);
7098                 cfs_rq->runtime_enabled = runtime_enabled;
7099                 cfs_rq->runtime_remaining = 0;
7100 
7101                 if (cfs_rq->throttled)
7102                         unthrottle_cfs_rq(cfs_rq);
7103                 raw_spin_unlock_irq(&rq->lock);
7104         }
7105         if (runtime_was_enabled && !runtime_enabled)
7106                 cfs_bandwidth_usage_dec();
7107 out_unlock:
7108         mutex_unlock(&cfs_constraints_mutex);
7109 
7110         return ret;
7111 }
7112 
7113 int tg_set_cfs_quota(struct task_group *tg, long cfs_quota_us)
7114 {
7115         u64 quota, period;
7116 
7117         period = ktime_to_ns(tg->cfs_bandwidth.period);
7118         if (cfs_quota_us < 0)
7119                 quota = RUNTIME_INF;
7120         else
7121                 quota = (u64)cfs_quota_us * NSEC_PER_USEC;
7122 
7123         return tg_set_cfs_bandwidth(tg, period, quota);
7124 }
7125 
7126 long tg_get_cfs_quota(struct task_group *tg)
7127 {
7128         u64 quota_us;
7129 
7130         if (tg->cfs_bandwidth.quota == RUNTIME_INF)
7131                 return -1;
7132 
7133         quota_us = tg->cfs_bandwidth.quota;
7134         do_div(quota_us, NSEC_PER_USEC);
7135 
7136         return quota_us;
7137 }
7138 
7139 int tg_set_cfs_period(struct task_group *tg, long cfs_period_us)
7140 {
7141         u64 quota, period;
7142 
7143         period = (u64)cfs_period_us * NSEC_PER_USEC;
7144         quota = tg->cfs_bandwidth.quota;
7145 
7146         return tg_set_cfs_bandwidth(tg, period, quota);
7147 }
7148 
7149 long tg_get_cfs_period(struct task_group *tg)
7150 {
7151         u64 cfs_period_us;
7152 
7153         cfs_period_us = ktime_to_ns(tg->cfs_bandwidth.period);
7154         do_div(cfs_period_us, NSEC_PER_USEC);
7155 
7156         return cfs_period_us;
7157 }
7158 
7159 static s64 cpu_cfs_quota_read_s64(struct cgroup_subsys_state *css,
7160                                   struct cftype *cft)
7161 {
7162         return tg_get_cfs_quota(css_tg(css));
7163 }
7164 
7165 static int cpu_cfs_quota_write_s64(struct cgroup_subsys_state *css,
7166                                    struct cftype *cftype, s64 cfs_quota_us)
7167 {
7168         return tg_set_cfs_quota(css_tg(css), cfs_quota_us);
7169 }
7170 
7171 static u64 cpu_cfs_period_read_u64(struct cgroup_subsys_state *css,
7172                                    struct cftype *cft)
7173 {
7174         return tg_get_cfs_period(css_tg(css));
7175 }
7176 
7177 static int cpu_cfs_period_write_u64(struct cgroup_subsys_state *css,
7178                                     struct cftype *cftype, u64 cfs_period_us)
7179 {
7180         return tg_set_cfs_period(css_tg(css), cfs_period_us);
7181 }
7182 
7183 struct cfs_schedulable_data {
7184         struct task_group *tg;
7185         u64 period, quota;
7186 };
7187 
7188 /*
7189  * normalize group quota/period to be quota/max_period
7190  * note: units are usecs
7191  */
7192 static u64 normalize_cfs_quota(struct task_group *tg,
7193                                struct cfs_schedulable_data *d)
7194 {
7195         u64 quota, period;
7196 
7197         if (tg == d->tg) {
7198                 period = d->period;
7199                 quota = d->quota;
7200         } else {
7201                 period = tg_get_cfs_period(tg);
7202                 quota = tg_get_cfs_quota(tg);
7203         }
7204 
7205         /* note: these should typically be equivalent */
7206         if (quota == RUNTIME_INF || quota == -1)
7207                 return RUNTIME_INF;
7208 
7209         return to_ratio(period, quota);
7210 }
7211 
7212 static int tg_cfs_schedulable_down(struct task_group *tg, void *data)
7213 {
7214         struct cfs_schedulable_data *d = data;
7215         struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
7216         s64 quota = 0, parent_quota = -1;
7217 
7218         if (!tg->parent) {
7219                 quota = RUNTIME_INF;
7220         } else {
7221                 struct cfs_bandwidth *parent_b = &tg->parent->cfs_bandwidth;
7222 
7223                 quota = normalize_cfs_quota(tg, d);
7224                 parent_quota = parent_b->hierarchal_quota;
7225 
7226                 /*
7227                  * ensure max(child_quota) <= parent_quota, inherit when no
7228                  * limit is set
7229                  */
7230                 if (quota == RUNTIME_INF)
7231                         quota = parent_quota;
7232                 else if (parent_quota != RUNTIME_INF && quota > parent_quota)
7233                         return -EINVAL;
7234         }
7235         cfs_b->hierarchal_quota = quota;
7236 
7237         return 0;
7238 }
7239 
7240 static int __cfs_schedulable(struct task_group *tg, u64 period, u64 quota)
7241 {
7242         int ret;
7243         struct cfs_schedulable_data data = {
7244                 .tg = tg,
7245                 .period = period,
7246                 .quota = quota,
7247         };
7248 
7249         if (quota != RUNTIME_INF) {
7250                 do_div(data.period, NSEC_PER_USEC);
7251                 do_div(data.quota, NSEC_PER_USEC);
7252         }
7253 
7254         rcu_read_lock();
7255         ret = walk_tg_tree(tg_cfs_schedulable_down, tg_nop, &data);
7256         rcu_read_unlock();
7257 
7258         return ret;
7259 }
7260 
7261 static int cpu_stats_show(struct cgroup_subsys_state *css, struct cftype *cft,
7262                 struct cgroup_map_cb *cb)
7263 {
7264         struct task_group *tg = css_tg(css);
7265         struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
7266 
7267         cb->fill(cb, "nr_periods", cfs_b->nr_periods);
7268         cb->fill(cb, "nr_throttled", cfs_b->nr_throttled);
7269         cb->fill(cb, "throttled_time", cfs_b->throttled_time);
7270 
7271         return 0;
7272 }
7273 #endif /* CONFIG_CFS_BANDWIDTH */
7274 #endif /* CONFIG_FAIR_GROUP_SCHED */
7275 
7276 #ifdef CONFIG_RT_GROUP_SCHED
7277 static int cpu_rt_runtime_write(struct cgroup_subsys_state *css,
7278                                 struct cftype *cft, s64 val)
7279 {
7280         return sched_group_set_rt_runtime(css_tg(css), val);
7281 }
7282 
7283 static s64 cpu_rt_runtime_read(struct cgroup_subsys_state *css,
7284                                struct cftype *cft)
7285 {
7286         return sched_group_rt_runtime(css_tg(css));
7287 }
7288 
7289 static int cpu_rt_period_write_uint(struct cgroup_subsys_state *css,
7290                                     struct cftype *cftype, u64 rt_period_us)
7291 {
7292         return sched_group_set_rt_period(css_tg(css), rt_period_us);
7293 }
7294 
7295 static u64 cpu_rt_period_read_uint(struct cgroup_subsys_state *css,
7296                                    struct cftype *cft)
7297 {
7298         return sched_group_rt_period(css_tg(css));
7299 }
7300 #endif /* CONFIG_RT_GROUP_SCHED */
7301 
7302 static struct cftype cpu_files[] = {
7303 #ifdef CONFIG_FAIR_GROUP_SCHED
7304         {
7305                 .name = "shares",
7306                 .read_u64 = cpu_shares_read_u64,
7307                 .write_u64 = cpu_shares_write_u64,
7308         },
7309 #endif
7310 #ifdef CONFIG_CFS_BANDWIDTH
7311         {
7312                 .name = "cfs_quota_us",
7313                 .read_s64 = cpu_cfs_quota_read_s64,
7314                 .write_s64 = cpu_cfs_quota_write_s64,
7315         },
7316         {
7317                 .name = "cfs_period_us",
7318                 .read_u64 = cpu_cfs_period_read_u64,
7319                 .write_u64 = cpu_cfs_period_write_u64,
7320         },
7321         {
7322                 .name = "stat",
7323                 .read_map = cpu_stats_show,
7324         },
7325 #endif
7326 #ifdef CONFIG_RT_GROUP_SCHED
7327         {
7328                 .name = "rt_runtime_us",
7329                 .read_s64 = cpu_rt_runtime_read,
7330                 .write_s64 = cpu_rt_runtime_write,
7331         },
7332         {
7333                 .name = "rt_period_us",
7334                 .read_u64 = cpu_rt_period_read_uint,
7335                 .write_u64 = cpu_rt_period_write_uint,
7336         },
7337 #endif
7338         { }     /* terminate */
7339 };
7340 
7341 struct cgroup_subsys cpu_cgroup_subsys = {
7342         .name           = "cpu",
7343         .css_alloc      = cpu_cgroup_css_alloc,
7344         .css_free       = cpu_cgroup_css_free,
7345         .css_online     = cpu_cgroup_css_online,
7346         .css_offline    = cpu_cgroup_css_offline,
7347         .can_attach     = cpu_cgroup_can_attach,
7348         .attach         = cpu_cgroup_attach,
7349         .exit           = cpu_cgroup_exit,
7350         .subsys_id      = cpu_cgroup_subsys_id,
7351         .base_cftypes   = cpu_files,
7352         .early_init     = 1,
7353 };
7354 
7355 #endif  /* CONFIG_CGROUP_SCHED */
7356 
7357 void dump_cpu_task(int cpu)
7358 {
7359         pr_info("Task dump for CPU %d:\n", cpu);
7360         sched_show_task(cpu_curr(cpu));
7361 }
7362 

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