Version:  2.0.40 2.2.26 2.4.37 2.6.39 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15

Linux/kernel/timer.c

  1 /*
  2  *  linux/kernel/timer.c
  3  *
  4  *  Kernel internal timers, basic process system calls
  5  *
  6  *  Copyright (C) 1991, 1992  Linus Torvalds
  7  *
  8  *  1997-01-28  Modified by Finn Arne Gangstad to make timers scale better.
  9  *
 10  *  1997-09-10  Updated NTP code according to technical memorandum Jan '96
 11  *              "A Kernel Model for Precision Timekeeping" by Dave Mills
 12  *  1998-12-24  Fixed a xtime SMP race (we need the xtime_lock rw spinlock to
 13  *              serialize accesses to xtime/lost_ticks).
 14  *                              Copyright (C) 1998  Andrea Arcangeli
 15  *  1999-03-10  Improved NTP compatibility by Ulrich Windl
 16  *  2002-05-31  Move sys_sysinfo here and make its locking sane, Robert Love
 17  *  2000-10-05  Implemented scalable SMP per-CPU timer handling.
 18  *                              Copyright (C) 2000, 2001, 2002  Ingo Molnar
 19  *              Designed by David S. Miller, Alexey Kuznetsov and Ingo Molnar
 20  */
 21 
 22 #include <linux/kernel_stat.h>
 23 #include <linux/export.h>
 24 #include <linux/interrupt.h>
 25 #include <linux/percpu.h>
 26 #include <linux/init.h>
 27 #include <linux/mm.h>
 28 #include <linux/swap.h>
 29 #include <linux/pid_namespace.h>
 30 #include <linux/notifier.h>
 31 #include <linux/thread_info.h>
 32 #include <linux/time.h>
 33 #include <linux/jiffies.h>
 34 #include <linux/posix-timers.h>
 35 #include <linux/cpu.h>
 36 #include <linux/syscalls.h>
 37 #include <linux/delay.h>
 38 #include <linux/tick.h>
 39 #include <linux/kallsyms.h>
 40 #include <linux/irq_work.h>
 41 #include <linux/sched.h>
 42 #include <linux/slab.h>
 43 
 44 #include <asm/uaccess.h>
 45 #include <asm/unistd.h>
 46 #include <asm/div64.h>
 47 #include <asm/timex.h>
 48 #include <asm/io.h>
 49 
 50 #define CREATE_TRACE_POINTS
 51 #include <trace/events/timer.h>
 52 
 53 u64 jiffies_64 __cacheline_aligned_in_smp = INITIAL_JIFFIES;
 54 
 55 EXPORT_SYMBOL(jiffies_64);
 56 
 57 /*
 58  * per-CPU timer vector definitions:
 59  */
 60 #define TVN_BITS (CONFIG_BASE_SMALL ? 4 : 6)
 61 #define TVR_BITS (CONFIG_BASE_SMALL ? 6 : 8)
 62 #define TVN_SIZE (1 << TVN_BITS)
 63 #define TVR_SIZE (1 << TVR_BITS)
 64 #define TVN_MASK (TVN_SIZE - 1)
 65 #define TVR_MASK (TVR_SIZE - 1)
 66 
 67 struct tvec {
 68         struct list_head vec[TVN_SIZE];
 69 };
 70 
 71 struct tvec_root {
 72         struct list_head vec[TVR_SIZE];
 73 };
 74 
 75 struct tvec_base {
 76         spinlock_t lock;
 77         struct timer_list *running_timer;
 78         unsigned long timer_jiffies;
 79         unsigned long next_timer;
 80         struct tvec_root tv1;
 81         struct tvec tv2;
 82         struct tvec tv3;
 83         struct tvec tv4;
 84         struct tvec tv5;
 85 } ____cacheline_aligned;
 86 
 87 struct tvec_base boot_tvec_bases;
 88 EXPORT_SYMBOL(boot_tvec_bases);
 89 static DEFINE_PER_CPU(struct tvec_base *, tvec_bases) = &boot_tvec_bases;
 90 
 91 /* Functions below help us manage 'deferrable' flag */
 92 static inline unsigned int tbase_get_deferrable(struct tvec_base *base)
 93 {
 94         return ((unsigned int)(unsigned long)base & TBASE_DEFERRABLE_FLAG);
 95 }
 96 
 97 static inline struct tvec_base *tbase_get_base(struct tvec_base *base)
 98 {
 99         return ((struct tvec_base *)((unsigned long)base & ~TBASE_DEFERRABLE_FLAG));
100 }
101 
102 static inline void timer_set_deferrable(struct timer_list *timer)
103 {
104         timer->base = TBASE_MAKE_DEFERRED(timer->base);
105 }
106 
107 static inline void
108 timer_set_base(struct timer_list *timer, struct tvec_base *new_base)
109 {
110         timer->base = (struct tvec_base *)((unsigned long)(new_base) |
111                                       tbase_get_deferrable(timer->base));
112 }
113 
114 static unsigned long round_jiffies_common(unsigned long j, int cpu,
115                 bool force_up)
116 {
117         int rem;
118         unsigned long original = j;
119 
120         /*
121          * We don't want all cpus firing their timers at once hitting the
122          * same lock or cachelines, so we skew each extra cpu with an extra
123          * 3 jiffies. This 3 jiffies came originally from the mm/ code which
124          * already did this.
125          * The skew is done by adding 3*cpunr, then round, then subtract this
126          * extra offset again.
127          */
128         j += cpu * 3;
129 
130         rem = j % HZ;
131 
132         /*
133          * If the target jiffie is just after a whole second (which can happen
134          * due to delays of the timer irq, long irq off times etc etc) then
135          * we should round down to the whole second, not up. Use 1/4th second
136          * as cutoff for this rounding as an extreme upper bound for this.
137          * But never round down if @force_up is set.
138          */
139         if (rem < HZ/4 && !force_up) /* round down */
140                 j = j - rem;
141         else /* round up */
142                 j = j - rem + HZ;
143 
144         /* now that we have rounded, subtract the extra skew again */
145         j -= cpu * 3;
146 
147         if (j <= jiffies) /* rounding ate our timeout entirely; */
148                 return original;
149         return j;
150 }
151 
152 /**
153  * __round_jiffies - function to round jiffies to a full second
154  * @j: the time in (absolute) jiffies that should be rounded
155  * @cpu: the processor number on which the timeout will happen
156  *
157  * __round_jiffies() rounds an absolute time in the future (in jiffies)
158  * up or down to (approximately) full seconds. This is useful for timers
159  * for which the exact time they fire does not matter too much, as long as
160  * they fire approximately every X seconds.
161  *
162  * By rounding these timers to whole seconds, all such timers will fire
163  * at the same time, rather than at various times spread out. The goal
164  * of this is to have the CPU wake up less, which saves power.
165  *
166  * The exact rounding is skewed for each processor to avoid all
167  * processors firing at the exact same time, which could lead
168  * to lock contention or spurious cache line bouncing.
169  *
170  * The return value is the rounded version of the @j parameter.
171  */
172 unsigned long __round_jiffies(unsigned long j, int cpu)
173 {
174         return round_jiffies_common(j, cpu, false);
175 }
176 EXPORT_SYMBOL_GPL(__round_jiffies);
177 
178 /**
179  * __round_jiffies_relative - function to round jiffies to a full second
180  * @j: the time in (relative) jiffies that should be rounded
181  * @cpu: the processor number on which the timeout will happen
182  *
183  * __round_jiffies_relative() rounds a time delta  in the future (in jiffies)
184  * up or down to (approximately) full seconds. This is useful for timers
185  * for which the exact time they fire does not matter too much, as long as
186  * they fire approximately every X seconds.
187  *
188  * By rounding these timers to whole seconds, all such timers will fire
189  * at the same time, rather than at various times spread out. The goal
190  * of this is to have the CPU wake up less, which saves power.
191  *
192  * The exact rounding is skewed for each processor to avoid all
193  * processors firing at the exact same time, which could lead
194  * to lock contention or spurious cache line bouncing.
195  *
196  * The return value is the rounded version of the @j parameter.
197  */
198 unsigned long __round_jiffies_relative(unsigned long j, int cpu)
199 {
200         unsigned long j0 = jiffies;
201 
202         /* Use j0 because jiffies might change while we run */
203         return round_jiffies_common(j + j0, cpu, false) - j0;
204 }
205 EXPORT_SYMBOL_GPL(__round_jiffies_relative);
206 
207 /**
208  * round_jiffies - function to round jiffies to a full second
209  * @j: the time in (absolute) jiffies that should be rounded
210  *
211  * round_jiffies() rounds an absolute time in the future (in jiffies)
212  * up or down to (approximately) full seconds. This is useful for timers
213  * for which the exact time they fire does not matter too much, as long as
214  * they fire approximately every X seconds.
215  *
216  * By rounding these timers to whole seconds, all such timers will fire
217  * at the same time, rather than at various times spread out. The goal
218  * of this is to have the CPU wake up less, which saves power.
219  *
220  * The return value is the rounded version of the @j parameter.
221  */
222 unsigned long round_jiffies(unsigned long j)
223 {
224         return round_jiffies_common(j, raw_smp_processor_id(), false);
225 }
226 EXPORT_SYMBOL_GPL(round_jiffies);
227 
228 /**
229  * round_jiffies_relative - function to round jiffies to a full second
230  * @j: the time in (relative) jiffies that should be rounded
231  *
232  * round_jiffies_relative() rounds a time delta  in the future (in jiffies)
233  * up or down to (approximately) full seconds. This is useful for timers
234  * for which the exact time they fire does not matter too much, as long as
235  * they fire approximately every X seconds.
236  *
237  * By rounding these timers to whole seconds, all such timers will fire
238  * at the same time, rather than at various times spread out. The goal
239  * of this is to have the CPU wake up less, which saves power.
240  *
241  * The return value is the rounded version of the @j parameter.
242  */
243 unsigned long round_jiffies_relative(unsigned long j)
244 {
245         return __round_jiffies_relative(j, raw_smp_processor_id());
246 }
247 EXPORT_SYMBOL_GPL(round_jiffies_relative);
248 
249 /**
250  * __round_jiffies_up - function to round jiffies up to a full second
251  * @j: the time in (absolute) jiffies that should be rounded
252  * @cpu: the processor number on which the timeout will happen
253  *
254  * This is the same as __round_jiffies() except that it will never
255  * round down.  This is useful for timeouts for which the exact time
256  * of firing does not matter too much, as long as they don't fire too
257  * early.
258  */
259 unsigned long __round_jiffies_up(unsigned long j, int cpu)
260 {
261         return round_jiffies_common(j, cpu, true);
262 }
263 EXPORT_SYMBOL_GPL(__round_jiffies_up);
264 
265 /**
266  * __round_jiffies_up_relative - function to round jiffies up to a full second
267  * @j: the time in (relative) jiffies that should be rounded
268  * @cpu: the processor number on which the timeout will happen
269  *
270  * This is the same as __round_jiffies_relative() except that it will never
271  * round down.  This is useful for timeouts for which the exact time
272  * of firing does not matter too much, as long as they don't fire too
273  * early.
274  */
275 unsigned long __round_jiffies_up_relative(unsigned long j, int cpu)
276 {
277         unsigned long j0 = jiffies;
278 
279         /* Use j0 because jiffies might change while we run */
280         return round_jiffies_common(j + j0, cpu, true) - j0;
281 }
282 EXPORT_SYMBOL_GPL(__round_jiffies_up_relative);
283 
284 /**
285  * round_jiffies_up - function to round jiffies up to a full second
286  * @j: the time in (absolute) jiffies that should be rounded
287  *
288  * This is the same as round_jiffies() except that it will never
289  * round down.  This is useful for timeouts for which the exact time
290  * of firing does not matter too much, as long as they don't fire too
291  * early.
292  */
293 unsigned long round_jiffies_up(unsigned long j)
294 {
295         return round_jiffies_common(j, raw_smp_processor_id(), true);
296 }
297 EXPORT_SYMBOL_GPL(round_jiffies_up);
298 
299 /**
300  * round_jiffies_up_relative - function to round jiffies up to a full second
301  * @j: the time in (relative) jiffies that should be rounded
302  *
303  * This is the same as round_jiffies_relative() except that it will never
304  * round down.  This is useful for timeouts for which the exact time
305  * of firing does not matter too much, as long as they don't fire too
306  * early.
307  */
308 unsigned long round_jiffies_up_relative(unsigned long j)
309 {
310         return __round_jiffies_up_relative(j, raw_smp_processor_id());
311 }
312 EXPORT_SYMBOL_GPL(round_jiffies_up_relative);
313 
314 /**
315  * set_timer_slack - set the allowed slack for a timer
316  * @timer: the timer to be modified
317  * @slack_hz: the amount of time (in jiffies) allowed for rounding
318  *
319  * Set the amount of time, in jiffies, that a certain timer has
320  * in terms of slack. By setting this value, the timer subsystem
321  * will schedule the actual timer somewhere between
322  * the time mod_timer() asks for, and that time plus the slack.
323  *
324  * By setting the slack to -1, a percentage of the delay is used
325  * instead.
326  */
327 void set_timer_slack(struct timer_list *timer, int slack_hz)
328 {
329         timer->slack = slack_hz;
330 }
331 EXPORT_SYMBOL_GPL(set_timer_slack);
332 
333 static void internal_add_timer(struct tvec_base *base, struct timer_list *timer)
334 {
335         unsigned long expires = timer->expires;
336         unsigned long idx = expires - base->timer_jiffies;
337         struct list_head *vec;
338 
339         if (idx < TVR_SIZE) {
340                 int i = expires & TVR_MASK;
341                 vec = base->tv1.vec + i;
342         } else if (idx < 1 << (TVR_BITS + TVN_BITS)) {
343                 int i = (expires >> TVR_BITS) & TVN_MASK;
344                 vec = base->tv2.vec + i;
345         } else if (idx < 1 << (TVR_BITS + 2 * TVN_BITS)) {
346                 int i = (expires >> (TVR_BITS + TVN_BITS)) & TVN_MASK;
347                 vec = base->tv3.vec + i;
348         } else if (idx < 1 << (TVR_BITS + 3 * TVN_BITS)) {
349                 int i = (expires >> (TVR_BITS + 2 * TVN_BITS)) & TVN_MASK;
350                 vec = base->tv4.vec + i;
351         } else if ((signed long) idx < 0) {
352                 /*
353                  * Can happen if you add a timer with expires == jiffies,
354                  * or you set a timer to go off in the past
355                  */
356                 vec = base->tv1.vec + (base->timer_jiffies & TVR_MASK);
357         } else {
358                 int i;
359                 /* If the timeout is larger than 0xffffffff on 64-bit
360                  * architectures then we use the maximum timeout:
361                  */
362                 if (idx > 0xffffffffUL) {
363                         idx = 0xffffffffUL;
364                         expires = idx + base->timer_jiffies;
365                 }
366                 i = (expires >> (TVR_BITS + 3 * TVN_BITS)) & TVN_MASK;
367                 vec = base->tv5.vec + i;
368         }
369         /*
370          * Timers are FIFO:
371          */
372         list_add_tail(&timer->entry, vec);
373 }
374 
375 #ifdef CONFIG_TIMER_STATS
376 void __timer_stats_timer_set_start_info(struct timer_list *timer, void *addr)
377 {
378         if (timer->start_site)
379                 return;
380 
381         timer->start_site = addr;
382         memcpy(timer->start_comm, current->comm, TASK_COMM_LEN);
383         timer->start_pid = current->pid;
384 }
385 
386 static void timer_stats_account_timer(struct timer_list *timer)
387 {
388         unsigned int flag = 0;
389 
390         if (likely(!timer->start_site))
391                 return;
392         if (unlikely(tbase_get_deferrable(timer->base)))
393                 flag |= TIMER_STATS_FLAG_DEFERRABLE;
394 
395         timer_stats_update_stats(timer, timer->start_pid, timer->start_site,
396                                  timer->function, timer->start_comm, flag);
397 }
398 
399 #else
400 static void timer_stats_account_timer(struct timer_list *timer) {}
401 #endif
402 
403 #ifdef CONFIG_DEBUG_OBJECTS_TIMERS
404 
405 static struct debug_obj_descr timer_debug_descr;
406 
407 static void *timer_debug_hint(void *addr)
408 {
409         return ((struct timer_list *) addr)->function;
410 }
411 
412 /*
413  * fixup_init is called when:
414  * - an active object is initialized
415  */
416 static int timer_fixup_init(void *addr, enum debug_obj_state state)
417 {
418         struct timer_list *timer = addr;
419 
420         switch (state) {
421         case ODEBUG_STATE_ACTIVE:
422                 del_timer_sync(timer);
423                 debug_object_init(timer, &timer_debug_descr);
424                 return 1;
425         default:
426                 return 0;
427         }
428 }
429 
430 /* Stub timer callback for improperly used timers. */
431 static void stub_timer(unsigned long data)
432 {
433         WARN_ON(1);
434 }
435 
436 /*
437  * fixup_activate is called when:
438  * - an active object is activated
439  * - an unknown object is activated (might be a statically initialized object)
440  */
441 static int timer_fixup_activate(void *addr, enum debug_obj_state state)
442 {
443         struct timer_list *timer = addr;
444 
445         switch (state) {
446 
447         case ODEBUG_STATE_NOTAVAILABLE:
448                 /*
449                  * This is not really a fixup. The timer was
450                  * statically initialized. We just make sure that it
451                  * is tracked in the object tracker.
452                  */
453                 if (timer->entry.next == NULL &&
454                     timer->entry.prev == TIMER_ENTRY_STATIC) {
455                         debug_object_init(timer, &timer_debug_descr);
456                         debug_object_activate(timer, &timer_debug_descr);
457                         return 0;
458                 } else {
459                         setup_timer(timer, stub_timer, 0);
460                         return 1;
461                 }
462                 return 0;
463 
464         case ODEBUG_STATE_ACTIVE:
465                 WARN_ON(1);
466 
467         default:
468                 return 0;
469         }
470 }
471 
472 /*
473  * fixup_free is called when:
474  * - an active object is freed
475  */
476 static int timer_fixup_free(void *addr, enum debug_obj_state state)
477 {
478         struct timer_list *timer = addr;
479 
480         switch (state) {
481         case ODEBUG_STATE_ACTIVE:
482                 del_timer_sync(timer);
483                 debug_object_free(timer, &timer_debug_descr);
484                 return 1;
485         default:
486                 return 0;
487         }
488 }
489 
490 /*
491  * fixup_assert_init is called when:
492  * - an untracked/uninit-ed object is found
493  */
494 static int timer_fixup_assert_init(void *addr, enum debug_obj_state state)
495 {
496         struct timer_list *timer = addr;
497 
498         switch (state) {
499         case ODEBUG_STATE_NOTAVAILABLE:
500                 if (timer->entry.prev == TIMER_ENTRY_STATIC) {
501                         /*
502                          * This is not really a fixup. The timer was
503                          * statically initialized. We just make sure that it
504                          * is tracked in the object tracker.
505                          */
506                         debug_object_init(timer, &timer_debug_descr);
507                         return 0;
508                 } else {
509                         setup_timer(timer, stub_timer, 0);
510                         return 1;
511                 }
512         default:
513                 return 0;
514         }
515 }
516 
517 static struct debug_obj_descr timer_debug_descr = {
518         .name                   = "timer_list",
519         .debug_hint             = timer_debug_hint,
520         .fixup_init             = timer_fixup_init,
521         .fixup_activate         = timer_fixup_activate,
522         .fixup_free             = timer_fixup_free,
523         .fixup_assert_init      = timer_fixup_assert_init,
524 };
525 
526 static inline void debug_timer_init(struct timer_list *timer)
527 {
528         debug_object_init(timer, &timer_debug_descr);
529 }
530 
531 static inline void debug_timer_activate(struct timer_list *timer)
532 {
533         debug_object_activate(timer, &timer_debug_descr);
534 }
535 
536 static inline void debug_timer_deactivate(struct timer_list *timer)
537 {
538         debug_object_deactivate(timer, &timer_debug_descr);
539 }
540 
541 static inline void debug_timer_free(struct timer_list *timer)
542 {
543         debug_object_free(timer, &timer_debug_descr);
544 }
545 
546 static inline void debug_timer_assert_init(struct timer_list *timer)
547 {
548         debug_object_assert_init(timer, &timer_debug_descr);
549 }
550 
551 static void __init_timer(struct timer_list *timer,
552                          const char *name,
553                          struct lock_class_key *key);
554 
555 void init_timer_on_stack_key(struct timer_list *timer,
556                              const char *name,
557                              struct lock_class_key *key)
558 {
559         debug_object_init_on_stack(timer, &timer_debug_descr);
560         __init_timer(timer, name, key);
561 }
562 EXPORT_SYMBOL_GPL(init_timer_on_stack_key);
563 
564 void destroy_timer_on_stack(struct timer_list *timer)
565 {
566         debug_object_free(timer, &timer_debug_descr);
567 }
568 EXPORT_SYMBOL_GPL(destroy_timer_on_stack);
569 
570 #else
571 static inline void debug_timer_init(struct timer_list *timer) { }
572 static inline void debug_timer_activate(struct timer_list *timer) { }
573 static inline void debug_timer_deactivate(struct timer_list *timer) { }
574 static inline void debug_timer_assert_init(struct timer_list *timer) { }
575 #endif
576 
577 static inline void debug_init(struct timer_list *timer)
578 {
579         debug_timer_init(timer);
580         trace_timer_init(timer);
581 }
582 
583 static inline void
584 debug_activate(struct timer_list *timer, unsigned long expires)
585 {
586         debug_timer_activate(timer);
587         trace_timer_start(timer, expires);
588 }
589 
590 static inline void debug_deactivate(struct timer_list *timer)
591 {
592         debug_timer_deactivate(timer);
593         trace_timer_cancel(timer);
594 }
595 
596 static inline void debug_assert_init(struct timer_list *timer)
597 {
598         debug_timer_assert_init(timer);
599 }
600 
601 static void __init_timer(struct timer_list *timer,
602                          const char *name,
603                          struct lock_class_key *key)
604 {
605         timer->entry.next = NULL;
606         timer->base = __raw_get_cpu_var(tvec_bases);
607         timer->slack = -1;
608 #ifdef CONFIG_TIMER_STATS
609         timer->start_site = NULL;
610         timer->start_pid = -1;
611         memset(timer->start_comm, 0, TASK_COMM_LEN);
612 #endif
613         lockdep_init_map(&timer->lockdep_map, name, key, 0);
614 }
615 
616 void setup_deferrable_timer_on_stack_key(struct timer_list *timer,
617                                          const char *name,
618                                          struct lock_class_key *key,
619                                          void (*function)(unsigned long),
620                                          unsigned long data)
621 {
622         timer->function = function;
623         timer->data = data;
624         init_timer_on_stack_key(timer, name, key);
625         timer_set_deferrable(timer);
626 }
627 EXPORT_SYMBOL_GPL(setup_deferrable_timer_on_stack_key);
628 
629 /**
630  * init_timer_key - initialize a timer
631  * @timer: the timer to be initialized
632  * @name: name of the timer
633  * @key: lockdep class key of the fake lock used for tracking timer
634  *       sync lock dependencies
635  *
636  * init_timer_key() must be done to a timer prior calling *any* of the
637  * other timer functions.
638  */
639 void init_timer_key(struct timer_list *timer,
640                     const char *name,
641                     struct lock_class_key *key)
642 {
643         debug_init(timer);
644         __init_timer(timer, name, key);
645 }
646 EXPORT_SYMBOL(init_timer_key);
647 
648 void init_timer_deferrable_key(struct timer_list *timer,
649                                const char *name,
650                                struct lock_class_key *key)
651 {
652         init_timer_key(timer, name, key);
653         timer_set_deferrable(timer);
654 }
655 EXPORT_SYMBOL(init_timer_deferrable_key);
656 
657 static inline void detach_timer(struct timer_list *timer,
658                                 int clear_pending)
659 {
660         struct list_head *entry = &timer->entry;
661 
662         debug_deactivate(timer);
663 
664         __list_del(entry->prev, entry->next);
665         if (clear_pending)
666                 entry->next = NULL;
667         entry->prev = LIST_POISON2;
668 }
669 
670 /*
671  * We are using hashed locking: holding per_cpu(tvec_bases).lock
672  * means that all timers which are tied to this base via timer->base are
673  * locked, and the base itself is locked too.
674  *
675  * So __run_timers/migrate_timers can safely modify all timers which could
676  * be found on ->tvX lists.
677  *
678  * When the timer's base is locked, and the timer removed from list, it is
679  * possible to set timer->base = NULL and drop the lock: the timer remains
680  * locked.
681  */
682 static struct tvec_base *lock_timer_base(struct timer_list *timer,
683                                         unsigned long *flags)
684         __acquires(timer->base->lock)
685 {
686         struct tvec_base *base;
687 
688         for (;;) {
689                 struct tvec_base *prelock_base = timer->base;
690                 base = tbase_get_base(prelock_base);
691                 if (likely(base != NULL)) {
692                         spin_lock_irqsave(&base->lock, *flags);
693                         if (likely(prelock_base == timer->base))
694                                 return base;
695                         /* The timer has migrated to another CPU */
696                         spin_unlock_irqrestore(&base->lock, *flags);
697                 }
698                 cpu_relax();
699         }
700 }
701 
702 static inline int
703 __mod_timer(struct timer_list *timer, unsigned long expires,
704                                                 bool pending_only, int pinned)
705 {
706         struct tvec_base *base, *new_base;
707         unsigned long flags;
708         int ret = 0 , cpu;
709 
710         timer_stats_timer_set_start_info(timer);
711         BUG_ON(!timer->function);
712 
713         base = lock_timer_base(timer, &flags);
714 
715         if (timer_pending(timer)) {
716                 detach_timer(timer, 0);
717                 if (timer->expires == base->next_timer &&
718                     !tbase_get_deferrable(timer->base))
719                         base->next_timer = base->timer_jiffies;
720                 ret = 1;
721         } else {
722                 if (pending_only)
723                         goto out_unlock;
724         }
725 
726         debug_activate(timer, expires);
727 
728         cpu = smp_processor_id();
729 
730 #if defined(CONFIG_NO_HZ) && defined(CONFIG_SMP)
731         if (!pinned && get_sysctl_timer_migration() && idle_cpu(cpu))
732                 cpu = get_nohz_timer_target();
733 #endif
734         new_base = per_cpu(tvec_bases, cpu);
735 
736         if (base != new_base) {
737                 /*
738                  * We are trying to schedule the timer on the local CPU.
739                  * However we can't change timer's base while it is running,
740                  * otherwise del_timer_sync() can't detect that the timer's
741                  * handler yet has not finished. This also guarantees that
742                  * the timer is serialized wrt itself.
743                  */
744                 if (likely(base->running_timer != timer)) {
745                         /* See the comment in lock_timer_base() */
746                         timer_set_base(timer, NULL);
747                         spin_unlock(&base->lock);
748                         base = new_base;
749                         spin_lock(&base->lock);
750                         timer_set_base(timer, base);
751                 }
752         }
753 
754         timer->expires = expires;
755         if (time_before(timer->expires, base->next_timer) &&
756             !tbase_get_deferrable(timer->base))
757                 base->next_timer = timer->expires;
758         internal_add_timer(base, timer);
759 
760 out_unlock:
761         spin_unlock_irqrestore(&base->lock, flags);
762 
763         return ret;
764 }
765 
766 /**
767  * mod_timer_pending - modify a pending timer's timeout
768  * @timer: the pending timer to be modified
769  * @expires: new timeout in jiffies
770  *
771  * mod_timer_pending() is the same for pending timers as mod_timer(),
772  * but will not re-activate and modify already deleted timers.
773  *
774  * It is useful for unserialized use of timers.
775  */
776 int mod_timer_pending(struct timer_list *timer, unsigned long expires)
777 {
778         return __mod_timer(timer, expires, true, TIMER_NOT_PINNED);
779 }
780 EXPORT_SYMBOL(mod_timer_pending);
781 
782 /*
783  * Decide where to put the timer while taking the slack into account
784  *
785  * Algorithm:
786  *   1) calculate the maximum (absolute) time
787  *   2) calculate the highest bit where the expires and new max are different
788  *   3) use this bit to make a mask
789  *   4) use the bitmask to round down the maximum time, so that all last
790  *      bits are zeros
791  */
792 static inline
793 unsigned long apply_slack(struct timer_list *timer, unsigned long expires)
794 {
795         unsigned long expires_limit, mask;
796         int bit;
797 
798         if (timer->slack >= 0) {
799                 expires_limit = expires + timer->slack;
800         } else {
801                 long delta = expires - jiffies;
802 
803                 if (delta < 256)
804                         return expires;
805 
806                 expires_limit = expires + delta / 256;
807         }
808         mask = expires ^ expires_limit;
809         if (mask == 0)
810                 return expires;
811 
812         bit = find_last_bit(&mask, BITS_PER_LONG);
813 
814         mask = (1 << bit) - 1;
815 
816         expires_limit = expires_limit & ~(mask);
817 
818         return expires_limit;
819 }
820 
821 /**
822  * mod_timer - modify a timer's timeout
823  * @timer: the timer to be modified
824  * @expires: new timeout in jiffies
825  *
826  * mod_timer() is a more efficient way to update the expire field of an
827  * active timer (if the timer is inactive it will be activated)
828  *
829  * mod_timer(timer, expires) is equivalent to:
830  *
831  *     del_timer(timer); timer->expires = expires; add_timer(timer);
832  *
833  * Note that if there are multiple unserialized concurrent users of the
834  * same timer, then mod_timer() is the only safe way to modify the timeout,
835  * since add_timer() cannot modify an already running timer.
836  *
837  * The function returns whether it has modified a pending timer or not.
838  * (ie. mod_timer() of an inactive timer returns 0, mod_timer() of an
839  * active timer returns 1.)
840  */
841 int mod_timer(struct timer_list *timer, unsigned long expires)
842 {
843         expires = apply_slack(timer, expires);
844 
845         /*
846          * This is a common optimization triggered by the
847          * networking code - if the timer is re-modified
848          * to be the same thing then just return:
849          */
850         if (timer_pending(timer) && timer->expires == expires)
851                 return 1;
852 
853         return __mod_timer(timer, expires, false, TIMER_NOT_PINNED);
854 }
855 EXPORT_SYMBOL(mod_timer);
856 
857 /**
858  * mod_timer_pinned - modify a timer's timeout
859  * @timer: the timer to be modified
860  * @expires: new timeout in jiffies
861  *
862  * mod_timer_pinned() is a way to update the expire field of an
863  * active timer (if the timer is inactive it will be activated)
864  * and not allow the timer to be migrated to a different CPU.
865  *
866  * mod_timer_pinned(timer, expires) is equivalent to:
867  *
868  *     del_timer(timer); timer->expires = expires; add_timer(timer);
869  */
870 int mod_timer_pinned(struct timer_list *timer, unsigned long expires)
871 {
872         if (timer->expires == expires && timer_pending(timer))
873                 return 1;
874 
875         return __mod_timer(timer, expires, false, TIMER_PINNED);
876 }
877 EXPORT_SYMBOL(mod_timer_pinned);
878 
879 /**
880  * add_timer - start a timer
881  * @timer: the timer to be added
882  *
883  * The kernel will do a ->function(->data) callback from the
884  * timer interrupt at the ->expires point in the future. The
885  * current time is 'jiffies'.
886  *
887  * The timer's ->expires, ->function (and if the handler uses it, ->data)
888  * fields must be set prior calling this function.
889  *
890  * Timers with an ->expires field in the past will be executed in the next
891  * timer tick.
892  */
893 void add_timer(struct timer_list *timer)
894 {
895         BUG_ON(timer_pending(timer));
896         mod_timer(timer, timer->expires);
897 }
898 EXPORT_SYMBOL(add_timer);
899 
900 /**
901  * add_timer_on - start a timer on a particular CPU
902  * @timer: the timer to be added
903  * @cpu: the CPU to start it on
904  *
905  * This is not very scalable on SMP. Double adds are not possible.
906  */
907 void add_timer_on(struct timer_list *timer, int cpu)
908 {
909         struct tvec_base *base = per_cpu(tvec_bases, cpu);
910         unsigned long flags;
911 
912         timer_stats_timer_set_start_info(timer);
913         BUG_ON(timer_pending(timer) || !timer->function);
914         spin_lock_irqsave(&base->lock, flags);
915         timer_set_base(timer, base);
916         debug_activate(timer, timer->expires);
917         if (time_before(timer->expires, base->next_timer) &&
918             !tbase_get_deferrable(timer->base))
919                 base->next_timer = timer->expires;
920         internal_add_timer(base, timer);
921         /*
922          * Check whether the other CPU is idle and needs to be
923          * triggered to reevaluate the timer wheel when nohz is
924          * active. We are protected against the other CPU fiddling
925          * with the timer by holding the timer base lock. This also
926          * makes sure that a CPU on the way to idle can not evaluate
927          * the timer wheel.
928          */
929         wake_up_idle_cpu(cpu);
930         spin_unlock_irqrestore(&base->lock, flags);
931 }
932 EXPORT_SYMBOL_GPL(add_timer_on);
933 
934 /**
935  * del_timer - deactive a timer.
936  * @timer: the timer to be deactivated
937  *
938  * del_timer() deactivates a timer - this works on both active and inactive
939  * timers.
940  *
941  * The function returns whether it has deactivated a pending timer or not.
942  * (ie. del_timer() of an inactive timer returns 0, del_timer() of an
943  * active timer returns 1.)
944  */
945 int del_timer(struct timer_list *timer)
946 {
947         struct tvec_base *base;
948         unsigned long flags;
949         int ret = 0;
950 
951         debug_assert_init(timer);
952 
953         timer_stats_timer_clear_start_info(timer);
954         if (timer_pending(timer)) {
955                 base = lock_timer_base(timer, &flags);
956                 if (timer_pending(timer)) {
957                         detach_timer(timer, 1);
958                         if (timer->expires == base->next_timer &&
959                             !tbase_get_deferrable(timer->base))
960                                 base->next_timer = base->timer_jiffies;
961                         ret = 1;
962                 }
963                 spin_unlock_irqrestore(&base->lock, flags);
964         }
965 
966         return ret;
967 }
968 EXPORT_SYMBOL(del_timer);
969 
970 /**
971  * try_to_del_timer_sync - Try to deactivate a timer
972  * @timer: timer do del
973  *
974  * This function tries to deactivate a timer. Upon successful (ret >= 0)
975  * exit the timer is not queued and the handler is not running on any CPU.
976  */
977 int try_to_del_timer_sync(struct timer_list *timer)
978 {
979         struct tvec_base *base;
980         unsigned long flags;
981         int ret = -1;
982 
983         debug_assert_init(timer);
984 
985         base = lock_timer_base(timer, &flags);
986 
987         if (base->running_timer == timer)
988                 goto out;
989 
990         timer_stats_timer_clear_start_info(timer);
991         ret = 0;
992         if (timer_pending(timer)) {
993                 detach_timer(timer, 1);
994                 if (timer->expires == base->next_timer &&
995                     !tbase_get_deferrable(timer->base))
996                         base->next_timer = base->timer_jiffies;
997                 ret = 1;
998         }
999 out:
1000         spin_unlock_irqrestore(&base->lock, flags);
1001 
1002         return ret;
1003 }
1004 EXPORT_SYMBOL(try_to_del_timer_sync);
1005 
1006 #ifdef CONFIG_SMP
1007 /**
1008  * del_timer_sync - deactivate a timer and wait for the handler to finish.
1009  * @timer: the timer to be deactivated
1010  *
1011  * This function only differs from del_timer() on SMP: besides deactivating
1012  * the timer it also makes sure the handler has finished executing on other
1013  * CPUs.
1014  *
1015  * Synchronization rules: Callers must prevent restarting of the timer,
1016  * otherwise this function is meaningless. It must not be called from
1017  * interrupt contexts. The caller must not hold locks which would prevent
1018  * completion of the timer's handler. The timer's handler must not call
1019  * add_timer_on(). Upon exit the timer is not queued and the handler is
1020  * not running on any CPU.
1021  *
1022  * Note: You must not hold locks that are held in interrupt context
1023  *   while calling this function. Even if the lock has nothing to do
1024  *   with the timer in question.  Here's why:
1025  *
1026  *    CPU0                             CPU1
1027  *    ----                             ----
1028  *                                   <SOFTIRQ>
1029  *                                   call_timer_fn();
1030  *                                     base->running_timer = mytimer;
1031  *  spin_lock_irq(somelock);
1032  *                                     <IRQ>
1033  *                                        spin_lock(somelock);
1034  *  del_timer_sync(mytimer);
1035  *   while (base->running_timer == mytimer);
1036  *
1037  * Now del_timer_sync() will never return and never release somelock.
1038  * The interrupt on the other CPU is waiting to grab somelock but
1039  * it has interrupted the softirq that CPU0 is waiting to finish.
1040  *
1041  * The function returns whether it has deactivated a pending timer or not.
1042  */
1043 int del_timer_sync(struct timer_list *timer)
1044 {
1045 #ifdef CONFIG_LOCKDEP
1046         unsigned long flags;
1047 
1048         /*
1049          * If lockdep gives a backtrace here, please reference
1050          * the synchronization rules above.
1051          */
1052         local_irq_save(flags);
1053         lock_map_acquire(&timer->lockdep_map);
1054         lock_map_release(&timer->lockdep_map);
1055         local_irq_restore(flags);
1056 #endif
1057         /*
1058          * don't use it in hardirq context, because it
1059          * could lead to deadlock.
1060          */
1061         WARN_ON(in_irq());
1062         for (;;) {
1063                 int ret = try_to_del_timer_sync(timer);
1064                 if (ret >= 0)
1065                         return ret;
1066                 cpu_relax();
1067         }
1068 }
1069 EXPORT_SYMBOL(del_timer_sync);
1070 #endif
1071 
1072 static int cascade(struct tvec_base *base, struct tvec *tv, int index)
1073 {
1074         /* cascade all the timers from tv up one level */
1075         struct timer_list *timer, *tmp;
1076         struct list_head tv_list;
1077 
1078         list_replace_init(tv->vec + index, &tv_list);
1079 
1080         /*
1081          * We are removing _all_ timers from the list, so we
1082          * don't have to detach them individually.
1083          */
1084         list_for_each_entry_safe(timer, tmp, &tv_list, entry) {
1085                 BUG_ON(tbase_get_base(timer->base) != base);
1086                 internal_add_timer(base, timer);
1087         }
1088 
1089         return index;
1090 }
1091 
1092 static void call_timer_fn(struct timer_list *timer, void (*fn)(unsigned long),
1093                           unsigned long data)
1094 {
1095         int preempt_count = preempt_count();
1096 
1097 #ifdef CONFIG_LOCKDEP
1098         /*
1099          * It is permissible to free the timer from inside the
1100          * function that is called from it, this we need to take into
1101          * account for lockdep too. To avoid bogus "held lock freed"
1102          * warnings as well as problems when looking into
1103          * timer->lockdep_map, make a copy and use that here.
1104          */
1105         struct lockdep_map lockdep_map = timer->lockdep_map;
1106 #endif
1107         /*
1108          * Couple the lock chain with the lock chain at
1109          * del_timer_sync() by acquiring the lock_map around the fn()
1110          * call here and in del_timer_sync().
1111          */
1112         lock_map_acquire(&lockdep_map);
1113 
1114         trace_timer_expire_entry(timer);
1115         fn(data);
1116         trace_timer_expire_exit(timer);
1117 
1118         lock_map_release(&lockdep_map);
1119 
1120         if (preempt_count != preempt_count()) {
1121                 WARN_ONCE(1, "timer: %pF preempt leak: %08x -> %08x\n",
1122                           fn, preempt_count, preempt_count());
1123                 /*
1124                  * Restore the preempt count. That gives us a decent
1125                  * chance to survive and extract information. If the
1126                  * callback kept a lock held, bad luck, but not worse
1127                  * than the BUG() we had.
1128                  */
1129                 preempt_count() = preempt_count;
1130         }
1131 }
1132 
1133 #define INDEX(N) ((base->timer_jiffies >> (TVR_BITS + (N) * TVN_BITS)) & TVN_MASK)
1134 
1135 /**
1136  * __run_timers - run all expired timers (if any) on this CPU.
1137  * @base: the timer vector to be processed.
1138  *
1139  * This function cascades all vectors and executes all expired timer
1140  * vectors.
1141  */
1142 static inline void __run_timers(struct tvec_base *base)
1143 {
1144         struct timer_list *timer;
1145 
1146         spin_lock_irq(&base->lock);
1147         while (time_after_eq(jiffies, base->timer_jiffies)) {
1148                 struct list_head work_list;
1149                 struct list_head *head = &work_list;
1150                 int index = base->timer_jiffies & TVR_MASK;
1151 
1152                 /*
1153                  * Cascade timers:
1154                  */
1155                 if (!index &&
1156                         (!cascade(base, &base->tv2, INDEX(0))) &&
1157                                 (!cascade(base, &base->tv3, INDEX(1))) &&
1158                                         !cascade(base, &base->tv4, INDEX(2)))
1159                         cascade(base, &base->tv5, INDEX(3));
1160                 ++base->timer_jiffies;
1161                 list_replace_init(base->tv1.vec + index, &work_list);
1162                 while (!list_empty(head)) {
1163                         void (*fn)(unsigned long);
1164                         unsigned long data;
1165 
1166                         timer = list_first_entry(head, struct timer_list,entry);
1167                         fn = timer->function;
1168                         data = timer->data;
1169 
1170                         timer_stats_account_timer(timer);
1171 
1172                         base->running_timer = timer;
1173                         detach_timer(timer, 1);
1174 
1175                         spin_unlock_irq(&base->lock);
1176                         call_timer_fn(timer, fn, data);
1177                         spin_lock_irq(&base->lock);
1178                 }
1179         }
1180         base->running_timer = NULL;
1181         spin_unlock_irq(&base->lock);
1182 }
1183 
1184 #ifdef CONFIG_NO_HZ
1185 /*
1186  * Find out when the next timer event is due to happen. This
1187  * is used on S/390 to stop all activity when a CPU is idle.
1188  * This function needs to be called with interrupts disabled.
1189  */
1190 static unsigned long __next_timer_interrupt(struct tvec_base *base)
1191 {
1192         unsigned long timer_jiffies = base->timer_jiffies;
1193         unsigned long expires = timer_jiffies + NEXT_TIMER_MAX_DELTA;
1194         int index, slot, array, found = 0;
1195         struct timer_list *nte;
1196         struct tvec *varray[4];
1197 
1198         /* Look for timer events in tv1. */
1199         index = slot = timer_jiffies & TVR_MASK;
1200         do {
1201                 list_for_each_entry(nte, base->tv1.vec + slot, entry) {
1202                         if (tbase_get_deferrable(nte->base))
1203                                 continue;
1204 
1205                         found = 1;
1206                         expires = nte->expires;
1207                         /* Look at the cascade bucket(s)? */
1208                         if (!index || slot < index)
1209                                 goto cascade;
1210                         return expires;
1211                 }
1212                 slot = (slot + 1) & TVR_MASK;
1213         } while (slot != index);
1214 
1215 cascade:
1216         /* Calculate the next cascade event */
1217         if (index)
1218                 timer_jiffies += TVR_SIZE - index;
1219         timer_jiffies >>= TVR_BITS;
1220 
1221         /* Check tv2-tv5. */
1222         varray[0] = &base->tv2;
1223         varray[1] = &base->tv3;
1224         varray[2] = &base->tv4;
1225         varray[3] = &base->tv5;
1226 
1227         for (array = 0; array < 4; array++) {
1228                 struct tvec *varp = varray[array];
1229 
1230                 index = slot = timer_jiffies & TVN_MASK;
1231                 do {
1232                         list_for_each_entry(nte, varp->vec + slot, entry) {
1233                                 if (tbase_get_deferrable(nte->base))
1234                                         continue;
1235 
1236                                 found = 1;
1237                                 if (time_before(nte->expires, expires))
1238                                         expires = nte->expires;
1239                         }
1240                         /*
1241                          * Do we still search for the first timer or are
1242                          * we looking up the cascade buckets ?
1243                          */
1244                         if (found) {
1245                                 /* Look at the cascade bucket(s)? */
1246                                 if (!index || slot < index)
1247                                         break;
1248                                 return expires;
1249                         }
1250                         slot = (slot + 1) & TVN_MASK;
1251                 } while (slot != index);
1252 
1253                 if (index)
1254                         timer_jiffies += TVN_SIZE - index;
1255                 timer_jiffies >>= TVN_BITS;
1256         }
1257         return expires;
1258 }
1259 
1260 /*
1261  * Check, if the next hrtimer event is before the next timer wheel
1262  * event:
1263  */
1264 static unsigned long cmp_next_hrtimer_event(unsigned long now,
1265                                             unsigned long expires)
1266 {
1267         ktime_t hr_delta = hrtimer_get_next_event();
1268         struct timespec tsdelta;
1269         unsigned long delta;
1270 
1271         if (hr_delta.tv64 == KTIME_MAX)
1272                 return expires;
1273 
1274         /*
1275          * Expired timer available, let it expire in the next tick
1276          */
1277         if (hr_delta.tv64 <= 0)
1278                 return now + 1;
1279 
1280         tsdelta = ktime_to_timespec(hr_delta);
1281         delta = timespec_to_jiffies(&tsdelta);
1282 
1283         /*
1284          * Limit the delta to the max value, which is checked in
1285          * tick_nohz_stop_sched_tick():
1286          */
1287         if (delta > NEXT_TIMER_MAX_DELTA)
1288                 delta = NEXT_TIMER_MAX_DELTA;
1289 
1290         /*
1291          * Take rounding errors in to account and make sure, that it
1292          * expires in the next tick. Otherwise we go into an endless
1293          * ping pong due to tick_nohz_stop_sched_tick() retriggering
1294          * the timer softirq
1295          */
1296         if (delta < 1)
1297                 delta = 1;
1298         now += delta;
1299         if (time_before(now, expires))
1300                 return now;
1301         return expires;
1302 }
1303 
1304 /**
1305  * get_next_timer_interrupt - return the jiffy of the next pending timer
1306  * @now: current time (in jiffies)
1307  */
1308 unsigned long get_next_timer_interrupt(unsigned long now)
1309 {
1310         struct tvec_base *base = __this_cpu_read(tvec_bases);
1311         unsigned long expires;
1312 
1313         /*
1314          * Pretend that there is no timer pending if the cpu is offline.
1315          * Possible pending timers will be migrated later to an active cpu.
1316          */
1317         if (cpu_is_offline(smp_processor_id()))
1318                 return now + NEXT_TIMER_MAX_DELTA;
1319         spin_lock(&base->lock);
1320         if (time_before_eq(base->next_timer, base->timer_jiffies))
1321                 base->next_timer = __next_timer_interrupt(base);
1322         expires = base->next_timer;
1323         spin_unlock(&base->lock);
1324 
1325         if (time_before_eq(expires, now))
1326                 return now;
1327 
1328         return cmp_next_hrtimer_event(now, expires);
1329 }
1330 #endif
1331 
1332 /*
1333  * Called from the timer interrupt handler to charge one tick to the current
1334  * process.  user_tick is 1 if the tick is user time, 0 for system.
1335  */
1336 void update_process_times(int user_tick)
1337 {
1338         struct task_struct *p = current;
1339         int cpu = smp_processor_id();
1340 
1341         /* Note: this timer irq context must be accounted for as well. */
1342         account_process_tick(p, user_tick);
1343         run_local_timers();
1344         rcu_check_callbacks(cpu, user_tick);
1345         printk_tick();
1346 #ifdef CONFIG_IRQ_WORK
1347         if (in_irq())
1348                 irq_work_run();
1349 #endif
1350         scheduler_tick();
1351         run_posix_cpu_timers(p);
1352 }
1353 
1354 /*
1355  * This function runs timers and the timer-tq in bottom half context.
1356  */
1357 static void run_timer_softirq(struct softirq_action *h)
1358 {
1359         struct tvec_base *base = __this_cpu_read(tvec_bases);
1360 
1361         hrtimer_run_pending();
1362 
1363         if (time_after_eq(jiffies, base->timer_jiffies))
1364                 __run_timers(base);
1365 }
1366 
1367 /*
1368  * Called by the local, per-CPU timer interrupt on SMP.
1369  */
1370 void run_local_timers(void)
1371 {
1372         hrtimer_run_queues();
1373         raise_softirq(TIMER_SOFTIRQ);
1374 }
1375 
1376 #ifdef __ARCH_WANT_SYS_ALARM
1377 
1378 /*
1379  * For backwards compatibility?  This can be done in libc so Alpha
1380  * and all newer ports shouldn't need it.
1381  */
1382 SYSCALL_DEFINE1(alarm, unsigned int, seconds)
1383 {
1384         return alarm_setitimer(seconds);
1385 }
1386 
1387 #endif
1388 
1389 #ifndef __alpha__
1390 
1391 /*
1392  * The Alpha uses getxpid, getxuid, and getxgid instead.  Maybe this
1393  * should be moved into arch/i386 instead?
1394  */
1395 
1396 /**
1397  * sys_getpid - return the thread group id of the current process
1398  *
1399  * Note, despite the name, this returns the tgid not the pid.  The tgid and
1400  * the pid are identical unless CLONE_THREAD was specified on clone() in
1401  * which case the tgid is the same in all threads of the same group.
1402  *
1403  * This is SMP safe as current->tgid does not change.
1404  */
1405 SYSCALL_DEFINE0(getpid)
1406 {
1407         return task_tgid_vnr(current);
1408 }
1409 
1410 /*
1411  * Accessing ->real_parent is not SMP-safe, it could
1412  * change from under us. However, we can use a stale
1413  * value of ->real_parent under rcu_read_lock(), see
1414  * release_task()->call_rcu(delayed_put_task_struct).
1415  */
1416 SYSCALL_DEFINE0(getppid)
1417 {
1418         int pid;
1419 
1420         rcu_read_lock();
1421         pid = task_tgid_vnr(rcu_dereference(current->real_parent));
1422         rcu_read_unlock();
1423 
1424         return pid;
1425 }
1426 
1427 SYSCALL_DEFINE0(getuid)
1428 {
1429         /* Only we change this so SMP safe */
1430         return current_uid();
1431 }
1432 
1433 SYSCALL_DEFINE0(geteuid)
1434 {
1435         /* Only we change this so SMP safe */
1436         return current_euid();
1437 }
1438 
1439 SYSCALL_DEFINE0(getgid)
1440 {
1441         /* Only we change this so SMP safe */
1442         return current_gid();
1443 }
1444 
1445 SYSCALL_DEFINE0(getegid)
1446 {
1447         /* Only we change this so SMP safe */
1448         return  current_egid();
1449 }
1450 
1451 #endif
1452 
1453 static void process_timeout(unsigned long __data)
1454 {
1455         wake_up_process((struct task_struct *)__data);
1456 }
1457 
1458 /**
1459  * schedule_timeout - sleep until timeout
1460  * @timeout: timeout value in jiffies
1461  *
1462  * Make the current task sleep until @timeout jiffies have
1463  * elapsed. The routine will return immediately unless
1464  * the current task state has been set (see set_current_state()).
1465  *
1466  * You can set the task state as follows -
1467  *
1468  * %TASK_UNINTERRUPTIBLE - at least @timeout jiffies are guaranteed to
1469  * pass before the routine returns. The routine will return 0
1470  *
1471  * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
1472  * delivered to the current task. In this case the remaining time
1473  * in jiffies will be returned, or 0 if the timer expired in time
1474  *
1475  * The current task state is guaranteed to be TASK_RUNNING when this
1476  * routine returns.
1477  *
1478  * Specifying a @timeout value of %MAX_SCHEDULE_TIMEOUT will schedule
1479  * the CPU away without a bound on the timeout. In this case the return
1480  * value will be %MAX_SCHEDULE_TIMEOUT.
1481  *
1482  * In all cases the return value is guaranteed to be non-negative.
1483  */
1484 signed long __sched schedule_timeout(signed long timeout)
1485 {
1486         struct timer_list timer;
1487         unsigned long expire;
1488 
1489         switch (timeout)
1490         {
1491         case MAX_SCHEDULE_TIMEOUT:
1492                 /*
1493                  * These two special cases are useful to be comfortable
1494                  * in the caller. Nothing more. We could take
1495                  * MAX_SCHEDULE_TIMEOUT from one of the negative value
1496                  * but I' d like to return a valid offset (>=0) to allow
1497                  * the caller to do everything it want with the retval.
1498                  */
1499                 schedule();
1500                 goto out;
1501         default:
1502                 /*
1503                  * Another bit of PARANOID. Note that the retval will be
1504                  * 0 since no piece of kernel is supposed to do a check
1505                  * for a negative retval of schedule_timeout() (since it
1506                  * should never happens anyway). You just have the printk()
1507                  * that will tell you if something is gone wrong and where.
1508                  */
1509                 if (timeout < 0) {
1510                         printk(KERN_ERR "schedule_timeout: wrong timeout "
1511                                 "value %lx\n", timeout);
1512                         dump_stack();
1513                         current->state = TASK_RUNNING;
1514                         goto out;
1515                 }
1516         }
1517 
1518         expire = timeout + jiffies;
1519 
1520         setup_timer_on_stack(&timer, process_timeout, (unsigned long)current);
1521         __mod_timer(&timer, expire, false, TIMER_NOT_PINNED);
1522         schedule();
1523         del_singleshot_timer_sync(&timer);
1524 
1525         /* Remove the timer from the object tracker */
1526         destroy_timer_on_stack(&timer);
1527 
1528         timeout = expire - jiffies;
1529 
1530  out:
1531         return timeout < 0 ? 0 : timeout;
1532 }
1533 EXPORT_SYMBOL(schedule_timeout);
1534 
1535 /*
1536  * We can use __set_current_state() here because schedule_timeout() calls
1537  * schedule() unconditionally.
1538  */
1539 signed long __sched schedule_timeout_interruptible(signed long timeout)
1540 {
1541         __set_current_state(TASK_INTERRUPTIBLE);
1542         return schedule_timeout(timeout);
1543 }
1544 EXPORT_SYMBOL(schedule_timeout_interruptible);
1545 
1546 signed long __sched schedule_timeout_killable(signed long timeout)
1547 {
1548         __set_current_state(TASK_KILLABLE);
1549         return schedule_timeout(timeout);
1550 }
1551 EXPORT_SYMBOL(schedule_timeout_killable);
1552 
1553 signed long __sched schedule_timeout_uninterruptible(signed long timeout)
1554 {
1555         __set_current_state(TASK_UNINTERRUPTIBLE);
1556         return schedule_timeout(timeout);
1557 }
1558 EXPORT_SYMBOL(schedule_timeout_uninterruptible);
1559 
1560 /* Thread ID - the internal kernel "pid" */
1561 SYSCALL_DEFINE0(gettid)
1562 {
1563         return task_pid_vnr(current);
1564 }
1565 
1566 /**
1567  * do_sysinfo - fill in sysinfo struct
1568  * @info: pointer to buffer to fill
1569  */
1570 int do_sysinfo(struct sysinfo *info)
1571 {
1572         unsigned long mem_total, sav_total;
1573         unsigned int mem_unit, bitcount;
1574         struct timespec tp;
1575 
1576         memset(info, 0, sizeof(struct sysinfo));
1577 
1578         ktime_get_ts(&tp);
1579         monotonic_to_bootbased(&tp);
1580         info->uptime = tp.tv_sec + (tp.tv_nsec ? 1 : 0);
1581 
1582         get_avenrun(info->loads, 0, SI_LOAD_SHIFT - FSHIFT);
1583 
1584         info->procs = nr_threads;
1585 
1586         si_meminfo(info);
1587         si_swapinfo(info);
1588 
1589         /*
1590          * If the sum of all the available memory (i.e. ram + swap)
1591          * is less than can be stored in a 32 bit unsigned long then
1592          * we can be binary compatible with 2.2.x kernels.  If not,
1593          * well, in that case 2.2.x was broken anyways...
1594          *
1595          *  -Erik Andersen <andersee@debian.org>
1596          */
1597 
1598         mem_total = info->totalram + info->totalswap;
1599         if (mem_total < info->totalram || mem_total < info->totalswap)
1600                 goto out;
1601         bitcount = 0;
1602         mem_unit = info->mem_unit;
1603         while (mem_unit > 1) {
1604                 bitcount++;
1605                 mem_unit >>= 1;
1606                 sav_total = mem_total;
1607                 mem_total <<= 1;
1608                 if (mem_total < sav_total)
1609                         goto out;
1610         }
1611 
1612         /*
1613          * If mem_total did not overflow, multiply all memory values by
1614          * info->mem_unit and set it to 1.  This leaves things compatible
1615          * with 2.2.x, and also retains compatibility with earlier 2.4.x
1616          * kernels...
1617          */
1618 
1619         info->mem_unit = 1;
1620         info->totalram <<= bitcount;
1621         info->freeram <<= bitcount;
1622         info->sharedram <<= bitcount;
1623         info->bufferram <<= bitcount;
1624         info->totalswap <<= bitcount;
1625         info->freeswap <<= bitcount;
1626         info->totalhigh <<= bitcount;
1627         info->freehigh <<= bitcount;
1628 
1629 out:
1630         return 0;
1631 }
1632 
1633 SYSCALL_DEFINE1(sysinfo, struct sysinfo __user *, info)
1634 {
1635         struct sysinfo val;
1636 
1637         do_sysinfo(&val);
1638 
1639         if (copy_to_user(info, &val, sizeof(struct sysinfo)))
1640                 return -EFAULT;
1641 
1642         return 0;
1643 }
1644 
1645 static int __cpuinit init_timers_cpu(int cpu)
1646 {
1647         int j;
1648         struct tvec_base *base;
1649         static char __cpuinitdata tvec_base_done[NR_CPUS];
1650 
1651         if (!tvec_base_done[cpu]) {
1652                 static char boot_done;
1653 
1654                 if (boot_done) {
1655                         /*
1656                          * The APs use this path later in boot
1657                          */
1658                         base = kmalloc_node(sizeof(*base),
1659                                                 GFP_KERNEL | __GFP_ZERO,
1660                                                 cpu_to_node(cpu));
1661                         if (!base)
1662                                 return -ENOMEM;
1663 
1664                         /* Make sure that tvec_base is 2 byte aligned */
1665                         if (tbase_get_deferrable(base)) {
1666                                 WARN_ON(1);
1667                                 kfree(base);
1668                                 return -ENOMEM;
1669                         }
1670                         per_cpu(tvec_bases, cpu) = base;
1671                 } else {
1672                         /*
1673                          * This is for the boot CPU - we use compile-time
1674                          * static initialisation because per-cpu memory isn't
1675                          * ready yet and because the memory allocators are not
1676                          * initialised either.
1677                          */
1678                         boot_done = 1;
1679                         base = &boot_tvec_bases;
1680                 }
1681                 tvec_base_done[cpu] = 1;
1682         } else {
1683                 base = per_cpu(tvec_bases, cpu);
1684         }
1685 
1686         spin_lock_init(&base->lock);
1687 
1688         for (j = 0; j < TVN_SIZE; j++) {
1689                 INIT_LIST_HEAD(base->tv5.vec + j);
1690                 INIT_LIST_HEAD(base->tv4.vec + j);
1691                 INIT_LIST_HEAD(base->tv3.vec + j);
1692                 INIT_LIST_HEAD(base->tv2.vec + j);
1693         }
1694         for (j = 0; j < TVR_SIZE; j++)
1695                 INIT_LIST_HEAD(base->tv1.vec + j);
1696 
1697         base->timer_jiffies = jiffies;
1698         base->next_timer = base->timer_jiffies;
1699         return 0;
1700 }
1701 
1702 #ifdef CONFIG_HOTPLUG_CPU
1703 static void migrate_timer_list(struct tvec_base *new_base, struct list_head *head)
1704 {
1705         struct timer_list *timer;
1706 
1707         while (!list_empty(head)) {
1708                 timer = list_first_entry(head, struct timer_list, entry);
1709                 detach_timer(timer, 0);
1710                 timer_set_base(timer, new_base);
1711                 if (time_before(timer->expires, new_base->next_timer) &&
1712                     !tbase_get_deferrable(timer->base))
1713                         new_base->next_timer = timer->expires;
1714                 internal_add_timer(new_base, timer);
1715         }
1716 }
1717 
1718 static void __cpuinit migrate_timers(int cpu)
1719 {
1720         struct tvec_base *old_base;
1721         struct tvec_base *new_base;
1722         int i;
1723 
1724         BUG_ON(cpu_online(cpu));
1725         old_base = per_cpu(tvec_bases, cpu);
1726         new_base = get_cpu_var(tvec_bases);
1727         /*
1728          * The caller is globally serialized and nobody else
1729          * takes two locks at once, deadlock is not possible.
1730          */
1731         spin_lock_irq(&new_base->lock);
1732         spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING);
1733 
1734         BUG_ON(old_base->running_timer);
1735 
1736         for (i = 0; i < TVR_SIZE; i++)
1737                 migrate_timer_list(new_base, old_base->tv1.vec + i);
1738         for (i = 0; i < TVN_SIZE; i++) {
1739                 migrate_timer_list(new_base, old_base->tv2.vec + i);
1740                 migrate_timer_list(new_base, old_base->tv3.vec + i);
1741                 migrate_timer_list(new_base, old_base->tv4.vec + i);
1742                 migrate_timer_list(new_base, old_base->tv5.vec + i);
1743         }
1744 
1745         spin_unlock(&old_base->lock);
1746         spin_unlock_irq(&new_base->lock);
1747         put_cpu_var(tvec_bases);
1748 }
1749 #endif /* CONFIG_HOTPLUG_CPU */
1750 
1751 static int __cpuinit timer_cpu_notify(struct notifier_block *self,
1752                                 unsigned long action, void *hcpu)
1753 {
1754         long cpu = (long)hcpu;
1755         int err;
1756 
1757         switch(action) {
1758         case CPU_UP_PREPARE:
1759         case CPU_UP_PREPARE_FROZEN:
1760                 err = init_timers_cpu(cpu);
1761                 if (err < 0)
1762                         return notifier_from_errno(err);
1763                 break;
1764 #ifdef CONFIG_HOTPLUG_CPU
1765         case CPU_DEAD:
1766         case CPU_DEAD_FROZEN:
1767                 migrate_timers(cpu);
1768                 break;
1769 #endif
1770         default:
1771                 break;
1772         }
1773         return NOTIFY_OK;
1774 }
1775 
1776 static struct notifier_block __cpuinitdata timers_nb = {
1777         .notifier_call  = timer_cpu_notify,
1778 };
1779 
1780 
1781 void __init init_timers(void)
1782 {
1783         int err = timer_cpu_notify(&timers_nb, (unsigned long)CPU_UP_PREPARE,
1784                                 (void *)(long)smp_processor_id());
1785 
1786         init_timer_stats();
1787 
1788         BUG_ON(err != NOTIFY_OK);
1789         register_cpu_notifier(&timers_nb);
1790         open_softirq(TIMER_SOFTIRQ, run_timer_softirq);
1791 }
1792 
1793 /**
1794  * msleep - sleep safely even with waitqueue interruptions
1795  * @msecs: Time in milliseconds to sleep for
1796  */
1797 void msleep(unsigned int msecs)
1798 {
1799         unsigned long timeout = msecs_to_jiffies(msecs) + 1;
1800 
1801         while (timeout)
1802                 timeout = schedule_timeout_uninterruptible(timeout);
1803 }
1804 
1805 EXPORT_SYMBOL(msleep);
1806 
1807 /**
1808  * msleep_interruptible - sleep waiting for signals
1809  * @msecs: Time in milliseconds to sleep for
1810  */
1811 unsigned long msleep_interruptible(unsigned int msecs)
1812 {
1813         unsigned long timeout = msecs_to_jiffies(msecs) + 1;
1814 
1815         while (timeout && !signal_pending(current))
1816                 timeout = schedule_timeout_interruptible(timeout);
1817         return jiffies_to_msecs(timeout);
1818 }
1819 
1820 EXPORT_SYMBOL(msleep_interruptible);
1821 
1822 static int __sched do_usleep_range(unsigned long min, unsigned long max)
1823 {
1824         ktime_t kmin;
1825         unsigned long delta;
1826 
1827         kmin = ktime_set(0, min * NSEC_PER_USEC);
1828         delta = (max - min) * NSEC_PER_USEC;
1829         return schedule_hrtimeout_range(&kmin, delta, HRTIMER_MODE_REL);
1830 }
1831 
1832 /**
1833  * usleep_range - Drop in replacement for udelay where wakeup is flexible
1834  * @min: Minimum time in usecs to sleep
1835  * @max: Maximum time in usecs to sleep
1836  */
1837 void usleep_range(unsigned long min, unsigned long max)
1838 {
1839         __set_current_state(TASK_UNINTERRUPTIBLE);
1840         do_usleep_range(min, max);
1841 }
1842 EXPORT_SYMBOL(usleep_range);
1843 

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