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1/*
2 * linux/kernel/timer.c
3 *
4 * Kernel internal timers
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/sched/sysctl.h>
43#include <linux/slab.h>
44#include <linux/compat.h>
45
46#include <asm/uaccess.h>
47#include <asm/unistd.h>
48#include <asm/div64.h>
49#include <asm/timex.h>
50#include <asm/io.h>
51
52#define CREATE_TRACE_POINTS
53#include <trace/events/timer.h>
54
55__visible u64 jiffies_64 __cacheline_aligned_in_smp = INITIAL_JIFFIES;
56
57EXPORT_SYMBOL(jiffies_64);
58
59/*
60 * per-CPU timer vector definitions:
61 */
62#define TVN_BITS (CONFIG_BASE_SMALL ? 4 : 6)
63#define TVR_BITS (CONFIG_BASE_SMALL ? 6 : 8)
64#define TVN_SIZE (1 << TVN_BITS)
65#define TVR_SIZE (1 << TVR_BITS)
66#define TVN_MASK (TVN_SIZE - 1)
67#define TVR_MASK (TVR_SIZE - 1)
68#define MAX_TVAL ((unsigned long)((1ULL << (TVR_BITS + 4*TVN_BITS)) - 1))
69
70struct tvec {
71 struct list_head vec[TVN_SIZE];
72};
73
74struct tvec_root {
75 struct list_head vec[TVR_SIZE];
76};
77
78struct tvec_base {
79 spinlock_t lock;
80 struct timer_list *running_timer;
81 unsigned long timer_jiffies;
82 unsigned long next_timer;
83 unsigned long active_timers;
84 unsigned long all_timers;
85 struct tvec_root tv1;
86 struct tvec tv2;
87 struct tvec tv3;
88 struct tvec tv4;
89 struct tvec tv5;
90} ____cacheline_aligned;
91
92struct tvec_base boot_tvec_bases;
93EXPORT_SYMBOL(boot_tvec_bases);
94static DEFINE_PER_CPU(struct tvec_base *, tvec_bases) = &boot_tvec_bases;
95
96/* Functions below help us manage 'deferrable' flag */
97static inline unsigned int tbase_get_deferrable(struct tvec_base *base)
98{
99 return ((unsigned int)(unsigned long)base & TIMER_DEFERRABLE);
100}
101
102static inline unsigned int tbase_get_irqsafe(struct tvec_base *base)
103{
104 return ((unsigned int)(unsigned long)base & TIMER_IRQSAFE);
105}
106
107static inline struct tvec_base *tbase_get_base(struct tvec_base *base)
108{
109 return ((struct tvec_base *)((unsigned long)base & ~TIMER_FLAG_MASK));
110}
111
112static inline void
113timer_set_base(struct timer_list *timer, struct tvec_base *new_base)
114{
115 unsigned long flags = (unsigned long)timer->base & TIMER_FLAG_MASK;
116
117 timer->base = (struct tvec_base *)((unsigned long)(new_base) | flags);
118}
119
120static unsigned long round_jiffies_common(unsigned long j, int cpu,
121 bool force_up)
122{
123 int rem;
124 unsigned long original = j;
125
126 /*
127 * We don't want all cpus firing their timers at once hitting the
128 * same lock or cachelines, so we skew each extra cpu with an extra
129 * 3 jiffies. This 3 jiffies came originally from the mm/ code which
130 * already did this.
131 * The skew is done by adding 3*cpunr, then round, then subtract this
132 * extra offset again.
133 */
134 j += cpu * 3;
135
136 rem = j % HZ;
137
138 /*
139 * If the target jiffie is just after a whole second (which can happen
140 * due to delays of the timer irq, long irq off times etc etc) then
141 * we should round down to the whole second, not up. Use 1/4th second
142 * as cutoff for this rounding as an extreme upper bound for this.
143 * But never round down if @force_up is set.
144 */
145 if (rem < HZ/4 && !force_up) /* round down */
146 j = j - rem;
147 else /* round up */
148 j = j - rem + HZ;
149
150 /* now that we have rounded, subtract the extra skew again */
151 j -= cpu * 3;
152
153 /*
154 * Make sure j is still in the future. Otherwise return the
155 * unmodified value.
156 */
157 return time_is_after_jiffies(j) ? j : original;
158}
159
160/**
161 * __round_jiffies - function to round jiffies to a full second
162 * @j: the time in (absolute) jiffies that should be rounded
163 * @cpu: the processor number on which the timeout will happen
164 *
165 * __round_jiffies() rounds an absolute time in the future (in jiffies)
166 * up or down to (approximately) full seconds. This is useful for timers
167 * for which the exact time they fire does not matter too much, as long as
168 * they fire approximately every X seconds.
169 *
170 * By rounding these timers to whole seconds, all such timers will fire
171 * at the same time, rather than at various times spread out. The goal
172 * of this is to have the CPU wake up less, which saves power.
173 *
174 * The exact rounding is skewed for each processor to avoid all
175 * processors firing at the exact same time, which could lead
176 * to lock contention or spurious cache line bouncing.
177 *
178 * The return value is the rounded version of the @j parameter.
179 */
180unsigned long __round_jiffies(unsigned long j, int cpu)
181{
182 return round_jiffies_common(j, cpu, false);
183}
184EXPORT_SYMBOL_GPL(__round_jiffies);
185
186/**
187 * __round_jiffies_relative - function to round jiffies to a full second
188 * @j: the time in (relative) jiffies that should be rounded
189 * @cpu: the processor number on which the timeout will happen
190 *
191 * __round_jiffies_relative() rounds a time delta in the future (in jiffies)
192 * up or down to (approximately) full seconds. This is useful for timers
193 * for which the exact time they fire does not matter too much, as long as
194 * they fire approximately every X seconds.
195 *
196 * By rounding these timers to whole seconds, all such timers will fire
197 * at the same time, rather than at various times spread out. The goal
198 * of this is to have the CPU wake up less, which saves power.
199 *
200 * The exact rounding is skewed for each processor to avoid all
201 * processors firing at the exact same time, which could lead
202 * to lock contention or spurious cache line bouncing.
203 *
204 * The return value is the rounded version of the @j parameter.
205 */
206unsigned long __round_jiffies_relative(unsigned long j, int cpu)
207{
208 unsigned long j0 = jiffies;
209
210 /* Use j0 because jiffies might change while we run */
211 return round_jiffies_common(j + j0, cpu, false) - j0;
212}
213EXPORT_SYMBOL_GPL(__round_jiffies_relative);
214
215/**
216 * round_jiffies - function to round jiffies to a full second
217 * @j: the time in (absolute) jiffies that should be rounded
218 *
219 * round_jiffies() rounds an absolute time in the future (in jiffies)
220 * up or down to (approximately) full seconds. This is useful for timers
221 * for which the exact time they fire does not matter too much, as long as
222 * they fire approximately every X seconds.
223 *
224 * By rounding these timers to whole seconds, all such timers will fire
225 * at the same time, rather than at various times spread out. The goal
226 * of this is to have the CPU wake up less, which saves power.
227 *
228 * The return value is the rounded version of the @j parameter.
229 */
230unsigned long round_jiffies(unsigned long j)
231{
232 return round_jiffies_common(j, raw_smp_processor_id(), false);
233}
234EXPORT_SYMBOL_GPL(round_jiffies);
235
236/**
237 * round_jiffies_relative - function to round jiffies to a full second
238 * @j: the time in (relative) jiffies that should be rounded
239 *
240 * round_jiffies_relative() rounds a time delta in the future (in jiffies)
241 * up or down to (approximately) full seconds. This is useful for timers
242 * for which the exact time they fire does not matter too much, as long as
243 * they fire approximately every X seconds.
244 *
245 * By rounding these timers to whole seconds, all such timers will fire
246 * at the same time, rather than at various times spread out. The goal
247 * of this is to have the CPU wake up less, which saves power.
248 *
249 * The return value is the rounded version of the @j parameter.
250 */
251unsigned long round_jiffies_relative(unsigned long j)
252{
253 return __round_jiffies_relative(j, raw_smp_processor_id());
254}
255EXPORT_SYMBOL_GPL(round_jiffies_relative);
256
257/**
258 * __round_jiffies_up - function to round jiffies up to a full second
259 * @j: the time in (absolute) jiffies that should be rounded
260 * @cpu: the processor number on which the timeout will happen
261 *
262 * This is the same as __round_jiffies() except that it will never
263 * round down. This is useful for timeouts for which the exact time
264 * of firing does not matter too much, as long as they don't fire too
265 * early.
266 */
267unsigned long __round_jiffies_up(unsigned long j, int cpu)
268{
269 return round_jiffies_common(j, cpu, true);
270}
271EXPORT_SYMBOL_GPL(__round_jiffies_up);
272
273/**
274 * __round_jiffies_up_relative - function to round jiffies up to a full second
275 * @j: the time in (relative) jiffies that should be rounded
276 * @cpu: the processor number on which the timeout will happen
277 *
278 * This is the same as __round_jiffies_relative() except that it will never
279 * round down. This is useful for timeouts for which the exact time
280 * of firing does not matter too much, as long as they don't fire too
281 * early.
282 */
283unsigned long __round_jiffies_up_relative(unsigned long j, int cpu)
284{
285 unsigned long j0 = jiffies;
286
287 /* Use j0 because jiffies might change while we run */
288 return round_jiffies_common(j + j0, cpu, true) - j0;
289}
290EXPORT_SYMBOL_GPL(__round_jiffies_up_relative);
291
292/**
293 * round_jiffies_up - function to round jiffies up to a full second
294 * @j: the time in (absolute) jiffies that should be rounded
295 *
296 * This is the same as round_jiffies() except that it will never
297 * round down. This is useful for timeouts for which the exact time
298 * of firing does not matter too much, as long as they don't fire too
299 * early.
300 */
301unsigned long round_jiffies_up(unsigned long j)
302{
303 return round_jiffies_common(j, raw_smp_processor_id(), true);
304}
305EXPORT_SYMBOL_GPL(round_jiffies_up);
306
307/**
308 * round_jiffies_up_relative - function to round jiffies up to a full second
309 * @j: the time in (relative) jiffies that should be rounded
310 *
311 * This is the same as round_jiffies_relative() except that it will never
312 * round down. This is useful for timeouts for which the exact time
313 * of firing does not matter too much, as long as they don't fire too
314 * early.
315 */
316unsigned long round_jiffies_up_relative(unsigned long j)
317{
318 return __round_jiffies_up_relative(j, raw_smp_processor_id());
319}
320EXPORT_SYMBOL_GPL(round_jiffies_up_relative);
321
322/**
323 * set_timer_slack - set the allowed slack for a timer
324 * @timer: the timer to be modified
325 * @slack_hz: the amount of time (in jiffies) allowed for rounding
326 *
327 * Set the amount of time, in jiffies, that a certain timer has
328 * in terms of slack. By setting this value, the timer subsystem
329 * will schedule the actual timer somewhere between
330 * the time mod_timer() asks for, and that time plus the slack.
331 *
332 * By setting the slack to -1, a percentage of the delay is used
333 * instead.
334 */
335void set_timer_slack(struct timer_list *timer, int slack_hz)
336{
337 timer->slack = slack_hz;
338}
339EXPORT_SYMBOL_GPL(set_timer_slack);
340
341/*
342 * If the list is empty, catch up ->timer_jiffies to the current time.
343 * The caller must hold the tvec_base lock. Returns true if the list
344 * was empty and therefore ->timer_jiffies was updated.
345 */
346static bool catchup_timer_jiffies(struct tvec_base *base)
347{
348 if (!base->all_timers) {
349 base->timer_jiffies = jiffies;
350 return true;
351 }
352 return false;
353}
354
355static void
356__internal_add_timer(struct tvec_base *base, struct timer_list *timer)
357{
358 unsigned long expires = timer->expires;
359 unsigned long idx = expires - base->timer_jiffies;
360 struct list_head *vec;
361
362 if (idx < TVR_SIZE) {
363 int i = expires & TVR_MASK;
364 vec = base->tv1.vec + i;
365 } else if (idx < 1 << (TVR_BITS + TVN_BITS)) {
366 int i = (expires >> TVR_BITS) & TVN_MASK;
367 vec = base->tv2.vec + i;
368 } else if (idx < 1 << (TVR_BITS + 2 * TVN_BITS)) {
369 int i = (expires >> (TVR_BITS + TVN_BITS)) & TVN_MASK;
370 vec = base->tv3.vec + i;
371 } else if (idx < 1 << (TVR_BITS + 3 * TVN_BITS)) {
372 int i = (expires >> (TVR_BITS + 2 * TVN_BITS)) & TVN_MASK;
373 vec = base->tv4.vec + i;
374 } else if ((signed long) idx < 0) {
375 /*
376 * Can happen if you add a timer with expires == jiffies,
377 * or you set a timer to go off in the past
378 */
379 vec = base->tv1.vec + (base->timer_jiffies & TVR_MASK);
380 } else {
381 int i;
382 /* If the timeout is larger than MAX_TVAL (on 64-bit
383 * architectures or with CONFIG_BASE_SMALL=1) then we
384 * use the maximum timeout.
385 */
386 if (idx > MAX_TVAL) {
387 idx = MAX_TVAL;
388 expires = idx + base->timer_jiffies;
389 }
390 i = (expires >> (TVR_BITS + 3 * TVN_BITS)) & TVN_MASK;
391 vec = base->tv5.vec + i;
392 }
393 /*
394 * Timers are FIFO:
395 */
396 list_add_tail(&timer->entry, vec);
397}
398
399static void internal_add_timer(struct tvec_base *base, struct timer_list *timer)
400{
401 (void)catchup_timer_jiffies(base);
402 __internal_add_timer(base, timer);
403 /*
404 * Update base->active_timers and base->next_timer
405 */
406 if (!tbase_get_deferrable(timer->base)) {
407 if (!base->active_timers++ ||
408 time_before(timer->expires, base->next_timer))
409 base->next_timer = timer->expires;
410 }
411 base->all_timers++;
412}
413
414#ifdef CONFIG_TIMER_STATS
415void __timer_stats_timer_set_start_info(struct timer_list *timer, void *addr)
416{
417 if (timer->start_site)
418 return;
419
420 timer->start_site = addr;
421 memcpy(timer->start_comm, current->comm, TASK_COMM_LEN);
422 timer->start_pid = current->pid;
423}
424
425static void timer_stats_account_timer(struct timer_list *timer)
426{
427 unsigned int flag = 0;
428
429 if (likely(!timer->start_site))
430 return;
431 if (unlikely(tbase_get_deferrable(timer->base)))
432 flag |= TIMER_STATS_FLAG_DEFERRABLE;
433
434 timer_stats_update_stats(timer, timer->start_pid, timer->start_site,
435 timer->function, timer->start_comm, flag);
436}
437
438#else
439static void timer_stats_account_timer(struct timer_list *timer) {}
440#endif
441
442#ifdef CONFIG_DEBUG_OBJECTS_TIMERS
443
444static struct debug_obj_descr timer_debug_descr;
445
446static void *timer_debug_hint(void *addr)
447{
448 return ((struct timer_list *) addr)->function;
449}
450
451/*
452 * fixup_init is called when:
453 * - an active object is initialized
454 */
455static int timer_fixup_init(void *addr, enum debug_obj_state state)
456{
457 struct timer_list *timer = addr;
458
459 switch (state) {
460 case ODEBUG_STATE_ACTIVE:
461 del_timer_sync(timer);
462 debug_object_init(timer, &timer_debug_descr);
463 return 1;
464 default:
465 return 0;
466 }
467}
468
469/* Stub timer callback for improperly used timers. */
470static void stub_timer(unsigned long data)
471{
472 WARN_ON(1);
473}
474
475/*
476 * fixup_activate is called when:
477 * - an active object is activated
478 * - an unknown object is activated (might be a statically initialized object)
479 */
480static int timer_fixup_activate(void *addr, enum debug_obj_state state)
481{
482 struct timer_list *timer = addr;
483
484 switch (state) {
485
486 case ODEBUG_STATE_NOTAVAILABLE:
487 /*
488 * This is not really a fixup. The timer was
489 * statically initialized. We just make sure that it
490 * is tracked in the object tracker.
491 */
492 if (timer->entry.next == NULL &&
493 timer->entry.prev == TIMER_ENTRY_STATIC) {
494 debug_object_init(timer, &timer_debug_descr);
495 debug_object_activate(timer, &timer_debug_descr);
496 return 0;
497 } else {
498 setup_timer(timer, stub_timer, 0);
499 return 1;
500 }
501 return 0;
502
503 case ODEBUG_STATE_ACTIVE:
504 WARN_ON(1);
505
506 default:
507 return 0;
508 }
509}
510
511/*
512 * fixup_free is called when:
513 * - an active object is freed
514 */
515static int timer_fixup_free(void *addr, enum debug_obj_state state)
516{
517 struct timer_list *timer = addr;
518
519 switch (state) {
520 case ODEBUG_STATE_ACTIVE:
521 del_timer_sync(timer);
522 debug_object_free(timer, &timer_debug_descr);
523 return 1;
524 default:
525 return 0;
526 }
527}
528
529/*
530 * fixup_assert_init is called when:
531 * - an untracked/uninit-ed object is found
532 */
533static int timer_fixup_assert_init(void *addr, enum debug_obj_state state)
534{
535 struct timer_list *timer = addr;
536
537 switch (state) {
538 case ODEBUG_STATE_NOTAVAILABLE:
539 if (timer->entry.prev == TIMER_ENTRY_STATIC) {
540 /*
541 * This is not really a fixup. The timer was
542 * statically initialized. We just make sure that it
543 * is tracked in the object tracker.
544 */
545 debug_object_init(timer, &timer_debug_descr);
546 return 0;
547 } else {
548 setup_timer(timer, stub_timer, 0);
549 return 1;
550 }
551 default:
552 return 0;
553 }
554}
555
556static struct debug_obj_descr timer_debug_descr = {
557 .name = "timer_list",
558 .debug_hint = timer_debug_hint,
559 .fixup_init = timer_fixup_init,
560 .fixup_activate = timer_fixup_activate,
561 .fixup_free = timer_fixup_free,
562 .fixup_assert_init = timer_fixup_assert_init,
563};
564
565static inline void debug_timer_init(struct timer_list *timer)
566{
567 debug_object_init(timer, &timer_debug_descr);
568}
569
570static inline void debug_timer_activate(struct timer_list *timer)
571{
572 debug_object_activate(timer, &timer_debug_descr);
573}
574
575static inline void debug_timer_deactivate(struct timer_list *timer)
576{
577 debug_object_deactivate(timer, &timer_debug_descr);
578}
579
580static inline void debug_timer_free(struct timer_list *timer)
581{
582 debug_object_free(timer, &timer_debug_descr);
583}
584
585static inline void debug_timer_assert_init(struct timer_list *timer)
586{
587 debug_object_assert_init(timer, &timer_debug_descr);
588}
589
590static void do_init_timer(struct timer_list *timer, unsigned int flags,
591 const char *name, struct lock_class_key *key);
592
593void init_timer_on_stack_key(struct timer_list *timer, unsigned int flags,
594 const char *name, struct lock_class_key *key)
595{
596 debug_object_init_on_stack(timer, &timer_debug_descr);
597 do_init_timer(timer, flags, name, key);
598}
599EXPORT_SYMBOL_GPL(init_timer_on_stack_key);
600
601void destroy_timer_on_stack(struct timer_list *timer)
602{
603 debug_object_free(timer, &timer_debug_descr);
604}
605EXPORT_SYMBOL_GPL(destroy_timer_on_stack);
606
607#else
608static inline void debug_timer_init(struct timer_list *timer) { }
609static inline void debug_timer_activate(struct timer_list *timer) { }
610static inline void debug_timer_deactivate(struct timer_list *timer) { }
611static inline void debug_timer_assert_init(struct timer_list *timer) { }
612#endif
613
614static inline void debug_init(struct timer_list *timer)
615{
616 debug_timer_init(timer);
617 trace_timer_init(timer);
618}
619
620static inline void
621debug_activate(struct timer_list *timer, unsigned long expires)
622{
623 debug_timer_activate(timer);
624 trace_timer_start(timer, expires);
625}
626
627static inline void debug_deactivate(struct timer_list *timer)
628{
629 debug_timer_deactivate(timer);
630 trace_timer_cancel(timer);
631}
632
633static inline void debug_assert_init(struct timer_list *timer)
634{
635 debug_timer_assert_init(timer);
636}
637
638static void do_init_timer(struct timer_list *timer, unsigned int flags,
639 const char *name, struct lock_class_key *key)
640{
641 struct tvec_base *base = __raw_get_cpu_var(tvec_bases);
642
643 timer->entry.next = NULL;
644 timer->base = (void *)((unsigned long)base | flags);
645 timer->slack = -1;
646#ifdef CONFIG_TIMER_STATS
647 timer->start_site = NULL;
648 timer->start_pid = -1;
649 memset(timer->start_comm, 0, TASK_COMM_LEN);
650#endif
651 lockdep_init_map(&timer->lockdep_map, name, key, 0);
652}
653
654/**
655 * init_timer_key - initialize a timer
656 * @timer: the timer to be initialized
657 * @flags: timer flags
658 * @name: name of the timer
659 * @key: lockdep class key of the fake lock used for tracking timer
660 * sync lock dependencies
661 *
662 * init_timer_key() must be done to a timer prior calling *any* of the
663 * other timer functions.
664 */
665void init_timer_key(struct timer_list *timer, unsigned int flags,
666 const char *name, struct lock_class_key *key)
667{
668 debug_init(timer);
669 do_init_timer(timer, flags, name, key);
670}
671EXPORT_SYMBOL(init_timer_key);
672
673static inline void detach_timer(struct timer_list *timer, bool clear_pending)
674{
675 struct list_head *entry = &timer->entry;
676
677 debug_deactivate(timer);
678
679 __list_del(entry->prev, entry->next);
680 if (clear_pending)
681 entry->next = NULL;
682 entry->prev = LIST_POISON2;
683}
684
685static inline void
686detach_expired_timer(struct timer_list *timer, struct tvec_base *base)
687{
688 detach_timer(timer, true);
689 if (!tbase_get_deferrable(timer->base))
690 base->active_timers--;
691 base->all_timers--;
692 (void)catchup_timer_jiffies(base);
693}
694
695static int detach_if_pending(struct timer_list *timer, struct tvec_base *base,
696 bool clear_pending)
697{
698 if (!timer_pending(timer))
699 return 0;
700
701 detach_timer(timer, clear_pending);
702 if (!tbase_get_deferrable(timer->base)) {
703 base->active_timers--;
704 if (timer->expires == base->next_timer)
705 base->next_timer = base->timer_jiffies;
706 }
707 base->all_timers--;
708 (void)catchup_timer_jiffies(base);
709 return 1;
710}
711
712/*
713 * We are using hashed locking: holding per_cpu(tvec_bases).lock
714 * means that all timers which are tied to this base via timer->base are
715 * locked, and the base itself is locked too.
716 *
717 * So __run_timers/migrate_timers can safely modify all timers which could
718 * be found on ->tvX lists.
719 *
720 * When the timer's base is locked, and the timer removed from list, it is
721 * possible to set timer->base = NULL and drop the lock: the timer remains
722 * locked.
723 */
724static struct tvec_base *lock_timer_base(struct timer_list *timer,
725 unsigned long *flags)
726 __acquires(timer->base->lock)
727{
728 struct tvec_base *base;
729
730 for (;;) {
731 struct tvec_base *prelock_base = timer->base;
732 base = tbase_get_base(prelock_base);
733 if (likely(base != NULL)) {
734 spin_lock_irqsave(&base->lock, *flags);
735 if (likely(prelock_base == timer->base))
736 return base;
737 /* The timer has migrated to another CPU */
738 spin_unlock_irqrestore(&base->lock, *flags);
739 }
740 cpu_relax();
741 }
742}
743
744static inline int
745__mod_timer(struct timer_list *timer, unsigned long expires,
746 bool pending_only, int pinned)
747{
748 struct tvec_base *base, *new_base;
749 unsigned long flags;
750 int ret = 0 , cpu;
751
752 timer_stats_timer_set_start_info(timer);
753 BUG_ON(!timer->function);
754
755 base = lock_timer_base(timer, &flags);
756
757 ret = detach_if_pending(timer, base, false);
758 if (!ret && pending_only)
759 goto out_unlock;
760
761 debug_activate(timer, expires);
762
763 cpu = get_nohz_timer_target(pinned);
764 new_base = per_cpu(tvec_bases, cpu);
765
766 if (base != new_base) {
767 /*
768 * We are trying to schedule the timer on the local CPU.
769 * However we can't change timer's base while it is running,
770 * otherwise del_timer_sync() can't detect that the timer's
771 * handler yet has not finished. This also guarantees that
772 * the timer is serialized wrt itself.
773 */
774 if (likely(base->running_timer != timer)) {
775 /* See the comment in lock_timer_base() */
776 timer_set_base(timer, NULL);
777 spin_unlock(&base->lock);
778 base = new_base;
779 spin_lock(&base->lock);
780 timer_set_base(timer, base);
781 }
782 }
783
784 timer->expires = expires;
785 internal_add_timer(base, timer);
786
787out_unlock:
788 spin_unlock_irqrestore(&base->lock, flags);
789
790 return ret;
791}
792
793/**
794 * mod_timer_pending - modify a pending timer's timeout
795 * @timer: the pending timer to be modified
796 * @expires: new timeout in jiffies
797 *
798 * mod_timer_pending() is the same for pending timers as mod_timer(),
799 * but will not re-activate and modify already deleted timers.
800 *
801 * It is useful for unserialized use of timers.
802 */
803int mod_timer_pending(struct timer_list *timer, unsigned long expires)
804{
805 return __mod_timer(timer, expires, true, TIMER_NOT_PINNED);
806}
807EXPORT_SYMBOL(mod_timer_pending);
808
809/*
810 * Decide where to put the timer while taking the slack into account
811 *
812 * Algorithm:
813 * 1) calculate the maximum (absolute) time
814 * 2) calculate the highest bit where the expires and new max are different
815 * 3) use this bit to make a mask
816 * 4) use the bitmask to round down the maximum time, so that all last
817 * bits are zeros
818 */
819static inline
820unsigned long apply_slack(struct timer_list *timer, unsigned long expires)
821{
822 unsigned long expires_limit, mask;
823 int bit;
824
825 if (timer->slack >= 0) {
826 expires_limit = expires + timer->slack;
827 } else {
828 long delta = expires - jiffies;
829
830 if (delta < 256)
831 return expires;
832
833 expires_limit = expires + delta / 256;
834 }
835 mask = expires ^ expires_limit;
836 if (mask == 0)
837 return expires;
838
839 bit = find_last_bit(&mask, BITS_PER_LONG);
840
841 mask = (1UL << bit) - 1;
842
843 expires_limit = expires_limit & ~(mask);
844
845 return expires_limit;
846}
847
848/**
849 * mod_timer - modify a timer's timeout
850 * @timer: the timer to be modified
851 * @expires: new timeout in jiffies
852 *
853 * mod_timer() is a more efficient way to update the expire field of an
854 * active timer (if the timer is inactive it will be activated)
855 *
856 * mod_timer(timer, expires) is equivalent to:
857 *
858 * del_timer(timer); timer->expires = expires; add_timer(timer);
859 *
860 * Note that if there are multiple unserialized concurrent users of the
861 * same timer, then mod_timer() is the only safe way to modify the timeout,
862 * since add_timer() cannot modify an already running timer.
863 *
864 * The function returns whether it has modified a pending timer or not.
865 * (ie. mod_timer() of an inactive timer returns 0, mod_timer() of an
866 * active timer returns 1.)
867 */
868int mod_timer(struct timer_list *timer, unsigned long expires)
869{
870 expires = apply_slack(timer, expires);
871
872 /*
873 * This is a common optimization triggered by the
874 * networking code - if the timer is re-modified
875 * to be the same thing then just return:
876 */
877 if (timer_pending(timer) && timer->expires == expires)
878 return 1;
879
880 return __mod_timer(timer, expires, false, TIMER_NOT_PINNED);
881}
882EXPORT_SYMBOL(mod_timer);
883
884/**
885 * mod_timer_pinned - modify a timer's timeout
886 * @timer: the timer to be modified
887 * @expires: new timeout in jiffies
888 *
889 * mod_timer_pinned() is a way to update the expire field of an
890 * active timer (if the timer is inactive it will be activated)
891 * and to ensure that the timer is scheduled on the current CPU.
892 *
893 * Note that this does not prevent the timer from being migrated
894 * when the current CPU goes offline. If this is a problem for
895 * you, use CPU-hotplug notifiers to handle it correctly, for
896 * example, cancelling the timer when the corresponding CPU goes
897 * offline.
898 *
899 * mod_timer_pinned(timer, expires) is equivalent to:
900 *
901 * del_timer(timer); timer->expires = expires; add_timer(timer);
902 */
903int mod_timer_pinned(struct timer_list *timer, unsigned long expires)
904{
905 if (timer->expires == expires && timer_pending(timer))
906 return 1;
907
908 return __mod_timer(timer, expires, false, TIMER_PINNED);
909}
910EXPORT_SYMBOL(mod_timer_pinned);
911
912/**
913 * add_timer - start a timer
914 * @timer: the timer to be added
915 *
916 * The kernel will do a ->function(->data) callback from the
917 * timer interrupt at the ->expires point in the future. The
918 * current time is 'jiffies'.
919 *
920 * The timer's ->expires, ->function (and if the handler uses it, ->data)
921 * fields must be set prior calling this function.
922 *
923 * Timers with an ->expires field in the past will be executed in the next
924 * timer tick.
925 */
926void add_timer(struct timer_list *timer)
927{
928 BUG_ON(timer_pending(timer));
929 mod_timer(timer, timer->expires);
930}
931EXPORT_SYMBOL(add_timer);
932
933/**
934 * add_timer_on - start a timer on a particular CPU
935 * @timer: the timer to be added
936 * @cpu: the CPU to start it on
937 *
938 * This is not very scalable on SMP. Double adds are not possible.
939 */
940void add_timer_on(struct timer_list *timer, int cpu)
941{
942 struct tvec_base *base = per_cpu(tvec_bases, cpu);
943 unsigned long flags;
944
945 timer_stats_timer_set_start_info(timer);
946 BUG_ON(timer_pending(timer) || !timer->function);
947 spin_lock_irqsave(&base->lock, flags);
948 timer_set_base(timer, base);
949 debug_activate(timer, timer->expires);
950 internal_add_timer(base, timer);
951 /*
952 * Check whether the other CPU is in dynticks mode and needs
953 * to be triggered to reevaluate the timer wheel.
954 * We are protected against the other CPU fiddling
955 * with the timer by holding the timer base lock. This also
956 * makes sure that a CPU on the way to stop its tick can not
957 * evaluate the timer wheel.
958 *
959 * Spare the IPI for deferrable timers on idle targets though.
960 * The next busy ticks will take care of it. Except full dynticks
961 * require special care against races with idle_cpu(), lets deal
962 * with that later.
963 */
964 if (!tbase_get_deferrable(timer->base) || tick_nohz_full_cpu(cpu))
965 wake_up_nohz_cpu(cpu);
966
967 spin_unlock_irqrestore(&base->lock, flags);
968}
969EXPORT_SYMBOL_GPL(add_timer_on);
970
971/**
972 * del_timer - deactive a timer.
973 * @timer: the timer to be deactivated
974 *
975 * del_timer() deactivates a timer - this works on both active and inactive
976 * timers.
977 *
978 * The function returns whether it has deactivated a pending timer or not.
979 * (ie. del_timer() of an inactive timer returns 0, del_timer() of an
980 * active timer returns 1.)
981 */
982int del_timer(struct timer_list *timer)
983{
984 struct tvec_base *base;
985 unsigned long flags;
986 int ret = 0;
987
988 debug_assert_init(timer);
989
990 timer_stats_timer_clear_start_info(timer);
991 if (timer_pending(timer)) {
992 base = lock_timer_base(timer, &flags);
993 ret = detach_if_pending(timer, base, true);
994 spin_unlock_irqrestore(&base->lock, flags);
995 }
996
997 return ret;
998}
999EXPORT_SYMBOL(del_timer);
1000
1001/**
1002 * try_to_del_timer_sync - Try to deactivate a timer
1003 * @timer: timer do del
1004 *
1005 * This function tries to deactivate a timer. Upon successful (ret >= 0)
1006 * exit the timer is not queued and the handler is not running on any CPU.
1007 */
1008int try_to_del_timer_sync(struct timer_list *timer)
1009{
1010 struct tvec_base *base;
1011 unsigned long flags;
1012 int ret = -1;
1013
1014 debug_assert_init(timer);
1015
1016 base = lock_timer_base(timer, &flags);
1017
1018 if (base->running_timer != timer) {
1019 timer_stats_timer_clear_start_info(timer);
1020 ret = detach_if_pending(timer, base, true);
1021 }
1022 spin_unlock_irqrestore(&base->lock, flags);
1023
1024 return ret;
1025}
1026EXPORT_SYMBOL(try_to_del_timer_sync);
1027
1028#ifdef CONFIG_SMP
1029/**
1030 * del_timer_sync - deactivate a timer and wait for the handler to finish.
1031 * @timer: the timer to be deactivated
1032 *
1033 * This function only differs from del_timer() on SMP: besides deactivating
1034 * the timer it also makes sure the handler has finished executing on other
1035 * CPUs.
1036 *
1037 * Synchronization rules: Callers must prevent restarting of the timer,
1038 * otherwise this function is meaningless. It must not be called from
1039 * interrupt contexts unless the timer is an irqsafe one. The caller must
1040 * not hold locks which would prevent completion of the timer's
1041 * handler. The timer's handler must not call add_timer_on(). Upon exit the
1042 * timer is not queued and the handler is not running on any CPU.
1043 *
1044 * Note: For !irqsafe timers, you must not hold locks that are held in
1045 * interrupt context while calling this function. Even if the lock has
1046 * nothing to do with the timer in question. Here's why:
1047 *
1048 * CPU0 CPU1
1049 * ---- ----
1050 * <SOFTIRQ>
1051 * call_timer_fn();
1052 * base->running_timer = mytimer;
1053 * spin_lock_irq(somelock);
1054 * <IRQ>
1055 * spin_lock(somelock);
1056 * del_timer_sync(mytimer);
1057 * while (base->running_timer == mytimer);
1058 *
1059 * Now del_timer_sync() will never return and never release somelock.
1060 * The interrupt on the other CPU is waiting to grab somelock but
1061 * it has interrupted the softirq that CPU0 is waiting to finish.
1062 *
1063 * The function returns whether it has deactivated a pending timer or not.
1064 */
1065int del_timer_sync(struct timer_list *timer)
1066{
1067#ifdef CONFIG_LOCKDEP
1068 unsigned long flags;
1069
1070 /*
1071 * If lockdep gives a backtrace here, please reference
1072 * the synchronization rules above.
1073 */
1074 local_irq_save(flags);
1075 lock_map_acquire(&timer->lockdep_map);
1076 lock_map_release(&timer->lockdep_map);
1077 local_irq_restore(flags);
1078#endif
1079 /*
1080 * don't use it in hardirq context, because it
1081 * could lead to deadlock.
1082 */
1083 WARN_ON(in_irq() && !tbase_get_irqsafe(timer->base));
1084 for (;;) {
1085 int ret = try_to_del_timer_sync(timer);
1086 if (ret >= 0)
1087 return ret;
1088 cpu_relax();
1089 }
1090}
1091EXPORT_SYMBOL(del_timer_sync);
1092#endif
1093
1094static int cascade(struct tvec_base *base, struct tvec *tv, int index)
1095{
1096 /* cascade all the timers from tv up one level */
1097 struct timer_list *timer, *tmp;
1098 struct list_head tv_list;
1099
1100 list_replace_init(tv->vec + index, &tv_list);
1101
1102 /*
1103 * We are removing _all_ timers from the list, so we
1104 * don't have to detach them individually.
1105 */
1106 list_for_each_entry_safe(timer, tmp, &tv_list, entry) {
1107 BUG_ON(tbase_get_base(timer->base) != base);
1108 /* No accounting, while moving them */
1109 __internal_add_timer(base, timer);
1110 }
1111
1112 return index;
1113}
1114
1115static void call_timer_fn(struct timer_list *timer, void (*fn)(unsigned long),
1116 unsigned long data)
1117{
1118 int count = preempt_count();
1119
1120#ifdef CONFIG_LOCKDEP
1121 /*
1122 * It is permissible to free the timer from inside the
1123 * function that is called from it, this we need to take into
1124 * account for lockdep too. To avoid bogus "held lock freed"
1125 * warnings as well as problems when looking into
1126 * timer->lockdep_map, make a copy and use that here.
1127 */
1128 struct lockdep_map lockdep_map;
1129
1130 lockdep_copy_map(&lockdep_map, &timer->lockdep_map);
1131#endif
1132 /*
1133 * Couple the lock chain with the lock chain at
1134 * del_timer_sync() by acquiring the lock_map around the fn()
1135 * call here and in del_timer_sync().
1136 */
1137 lock_map_acquire(&lockdep_map);
1138
1139 trace_timer_expire_entry(timer);
1140 fn(data);
1141 trace_timer_expire_exit(timer);
1142
1143 lock_map_release(&lockdep_map);
1144
1145 if (count != preempt_count()) {
1146 WARN_ONCE(1, "timer: %pF preempt leak: %08x -> %08x\n",
1147 fn, count, preempt_count());
1148 /*
1149 * Restore the preempt count. That gives us a decent
1150 * chance to survive and extract information. If the
1151 * callback kept a lock held, bad luck, but not worse
1152 * than the BUG() we had.
1153 */
1154 preempt_count_set(count);
1155 }
1156}
1157
1158#define INDEX(N) ((base->timer_jiffies >> (TVR_BITS + (N) * TVN_BITS)) & TVN_MASK)
1159
1160/**
1161 * __run_timers - run all expired timers (if any) on this CPU.
1162 * @base: the timer vector to be processed.
1163 *
1164 * This function cascades all vectors and executes all expired timer
1165 * vectors.
1166 */
1167static inline void __run_timers(struct tvec_base *base)
1168{
1169 struct timer_list *timer;
1170
1171 spin_lock_irq(&base->lock);
1172 if (catchup_timer_jiffies(base)) {
1173 spin_unlock_irq(&base->lock);
1174 return;
1175 }
1176 while (time_after_eq(jiffies, base->timer_jiffies)) {
1177 struct list_head work_list;
1178 struct list_head *head = &work_list;
1179 int index = base->timer_jiffies & TVR_MASK;
1180
1181 /*
1182 * Cascade timers:
1183 */
1184 if (!index &&
1185 (!cascade(base, &base->tv2, INDEX(0))) &&
1186 (!cascade(base, &base->tv3, INDEX(1))) &&
1187 !cascade(base, &base->tv4, INDEX(2)))
1188 cascade(base, &base->tv5, INDEX(3));
1189 ++base->timer_jiffies;
1190 list_replace_init(base->tv1.vec + index, head);
1191 while (!list_empty(head)) {
1192 void (*fn)(unsigned long);
1193 unsigned long data;
1194 bool irqsafe;
1195
1196 timer = list_first_entry(head, struct timer_list,entry);
1197 fn = timer->function;
1198 data = timer->data;
1199 irqsafe = tbase_get_irqsafe(timer->base);
1200
1201 timer_stats_account_timer(timer);
1202
1203 base->running_timer = timer;
1204 detach_expired_timer(timer, base);
1205
1206 if (irqsafe) {
1207 spin_unlock(&base->lock);
1208 call_timer_fn(timer, fn, data);
1209 spin_lock(&base->lock);
1210 } else {
1211 spin_unlock_irq(&base->lock);
1212 call_timer_fn(timer, fn, data);
1213 spin_lock_irq(&base->lock);
1214 }
1215 }
1216 }
1217 base->running_timer = NULL;
1218 spin_unlock_irq(&base->lock);
1219}
1220
1221#ifdef CONFIG_NO_HZ_COMMON
1222/*
1223 * Find out when the next timer event is due to happen. This
1224 * is used on S/390 to stop all activity when a CPU is idle.
1225 * This function needs to be called with interrupts disabled.
1226 */
1227static unsigned long __next_timer_interrupt(struct tvec_base *base)
1228{
1229 unsigned long timer_jiffies = base->timer_jiffies;
1230 unsigned long expires = timer_jiffies + NEXT_TIMER_MAX_DELTA;
1231 int index, slot, array, found = 0;
1232 struct timer_list *nte;
1233 struct tvec *varray[4];
1234
1235 /* Look for timer events in tv1. */
1236 index = slot = timer_jiffies & TVR_MASK;
1237 do {
1238 list_for_each_entry(nte, base->tv1.vec + slot, entry) {
1239 if (tbase_get_deferrable(nte->base))
1240 continue;
1241
1242 found = 1;
1243 expires = nte->expires;
1244 /* Look at the cascade bucket(s)? */
1245 if (!index || slot < index)
1246 goto cascade;
1247 return expires;
1248 }
1249 slot = (slot + 1) & TVR_MASK;
1250 } while (slot != index);
1251
1252cascade:
1253 /* Calculate the next cascade event */
1254 if (index)
1255 timer_jiffies += TVR_SIZE - index;
1256 timer_jiffies >>= TVR_BITS;
1257
1258 /* Check tv2-tv5. */
1259 varray[0] = &base->tv2;
1260 varray[1] = &base->tv3;
1261 varray[2] = &base->tv4;
1262 varray[3] = &base->tv5;
1263
1264 for (array = 0; array < 4; array++) {
1265 struct tvec *varp = varray[array];
1266
1267 index = slot = timer_jiffies & TVN_MASK;
1268 do {
1269 list_for_each_entry(nte, varp->vec + slot, entry) {
1270 if (tbase_get_deferrable(nte->base))
1271 continue;
1272
1273 found = 1;
1274 if (time_before(nte->expires, expires))
1275 expires = nte->expires;
1276 }
1277 /*
1278 * Do we still search for the first timer or are
1279 * we looking up the cascade buckets ?
1280 */
1281 if (found) {
1282 /* Look at the cascade bucket(s)? */
1283 if (!index || slot < index)
1284 break;
1285 return expires;
1286 }
1287 slot = (slot + 1) & TVN_MASK;
1288 } while (slot != index);
1289
1290 if (index)
1291 timer_jiffies += TVN_SIZE - index;
1292 timer_jiffies >>= TVN_BITS;
1293 }
1294 return expires;
1295}
1296
1297/*
1298 * Check, if the next hrtimer event is before the next timer wheel
1299 * event:
1300 */
1301static unsigned long cmp_next_hrtimer_event(unsigned long now,
1302 unsigned long expires)
1303{
1304 ktime_t hr_delta = hrtimer_get_next_event();
1305 struct timespec tsdelta;
1306 unsigned long delta;
1307
1308 if (hr_delta.tv64 == KTIME_MAX)
1309 return expires;
1310
1311 /*
1312 * Expired timer available, let it expire in the next tick
1313 */
1314 if (hr_delta.tv64 <= 0)
1315 return now + 1;
1316
1317 tsdelta = ktime_to_timespec(hr_delta);
1318 delta = timespec_to_jiffies(&tsdelta);
1319
1320 /*
1321 * Limit the delta to the max value, which is checked in
1322 * tick_nohz_stop_sched_tick():
1323 */
1324 if (delta > NEXT_TIMER_MAX_DELTA)
1325 delta = NEXT_TIMER_MAX_DELTA;
1326
1327 /*
1328 * Take rounding errors in to account and make sure, that it
1329 * expires in the next tick. Otherwise we go into an endless
1330 * ping pong due to tick_nohz_stop_sched_tick() retriggering
1331 * the timer softirq
1332 */
1333 if (delta < 1)
1334 delta = 1;
1335 now += delta;
1336 if (time_before(now, expires))
1337 return now;
1338 return expires;
1339}
1340
1341/**
1342 * get_next_timer_interrupt - return the jiffy of the next pending timer
1343 * @now: current time (in jiffies)
1344 */
1345unsigned long get_next_timer_interrupt(unsigned long now)
1346{
1347 struct tvec_base *base = __this_cpu_read(tvec_bases);
1348 unsigned long expires = now + NEXT_TIMER_MAX_DELTA;
1349
1350 /*
1351 * Pretend that there is no timer pending if the cpu is offline.
1352 * Possible pending timers will be migrated later to an active cpu.
1353 */
1354 if (cpu_is_offline(smp_processor_id()))
1355 return expires;
1356
1357 spin_lock(&base->lock);
1358 if (base->active_timers) {
1359 if (time_before_eq(base->next_timer, base->timer_jiffies))
1360 base->next_timer = __next_timer_interrupt(base);
1361 expires = base->next_timer;
1362 }
1363 spin_unlock(&base->lock);
1364
1365 if (time_before_eq(expires, now))
1366 return now;
1367
1368 return cmp_next_hrtimer_event(now, expires);
1369}
1370#endif
1371
1372/*
1373 * Called from the timer interrupt handler to charge one tick to the current
1374 * process. user_tick is 1 if the tick is user time, 0 for system.
1375 */
1376void update_process_times(int user_tick)
1377{
1378 struct task_struct *p = current;
1379 int cpu = smp_processor_id();
1380
1381 /* Note: this timer irq context must be accounted for as well. */
1382 account_process_tick(p, user_tick);
1383 run_local_timers();
1384 rcu_check_callbacks(cpu, user_tick);
1385#ifdef CONFIG_IRQ_WORK
1386 if (in_irq())
1387 irq_work_run();
1388#endif
1389 scheduler_tick();
1390 run_posix_cpu_timers(p);
1391}
1392
1393/*
1394 * This function runs timers and the timer-tq in bottom half context.
1395 */
1396static void run_timer_softirq(struct softirq_action *h)
1397{
1398 struct tvec_base *base = __this_cpu_read(tvec_bases);
1399
1400 hrtimer_run_pending();
1401
1402 if (time_after_eq(jiffies, base->timer_jiffies))
1403 __run_timers(base);
1404}
1405
1406/*
1407 * Called by the local, per-CPU timer interrupt on SMP.
1408 */
1409void run_local_timers(void)
1410{
1411 hrtimer_run_queues();
1412 raise_softirq(TIMER_SOFTIRQ);
1413}
1414
1415#ifdef __ARCH_WANT_SYS_ALARM
1416
1417/*
1418 * For backwards compatibility? This can be done in libc so Alpha
1419 * and all newer ports shouldn't need it.
1420 */
1421SYSCALL_DEFINE1(alarm, unsigned int, seconds)
1422{
1423 return alarm_setitimer(seconds);
1424}
1425
1426#endif
1427
1428static void process_timeout(unsigned long __data)
1429{
1430 wake_up_process((struct task_struct *)__data);
1431}
1432
1433/**
1434 * schedule_timeout - sleep until timeout
1435 * @timeout: timeout value in jiffies
1436 *
1437 * Make the current task sleep until @timeout jiffies have
1438 * elapsed. The routine will return immediately unless
1439 * the current task state has been set (see set_current_state()).
1440 *
1441 * You can set the task state as follows -
1442 *
1443 * %TASK_UNINTERRUPTIBLE - at least @timeout jiffies are guaranteed to
1444 * pass before the routine returns. The routine will return 0
1445 *
1446 * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
1447 * delivered to the current task. In this case the remaining time
1448 * in jiffies will be returned, or 0 if the timer expired in time
1449 *
1450 * The current task state is guaranteed to be TASK_RUNNING when this
1451 * routine returns.
1452 *
1453 * Specifying a @timeout value of %MAX_SCHEDULE_TIMEOUT will schedule
1454 * the CPU away without a bound on the timeout. In this case the return
1455 * value will be %MAX_SCHEDULE_TIMEOUT.
1456 *
1457 * In all cases the return value is guaranteed to be non-negative.
1458 */
1459signed long __sched schedule_timeout(signed long timeout)
1460{
1461 struct timer_list timer;
1462 unsigned long expire;
1463
1464 switch (timeout)
1465 {
1466 case MAX_SCHEDULE_TIMEOUT:
1467 /*
1468 * These two special cases are useful to be comfortable
1469 * in the caller. Nothing more. We could take
1470 * MAX_SCHEDULE_TIMEOUT from one of the negative value
1471 * but I' d like to return a valid offset (>=0) to allow
1472 * the caller to do everything it want with the retval.
1473 */
1474 schedule();
1475 goto out;
1476 default:
1477 /*
1478 * Another bit of PARANOID. Note that the retval will be
1479 * 0 since no piece of kernel is supposed to do a check
1480 * for a negative retval of schedule_timeout() (since it
1481 * should never happens anyway). You just have the printk()
1482 * that will tell you if something is gone wrong and where.
1483 */
1484 if (timeout < 0) {
1485 printk(KERN_ERR "schedule_timeout: wrong timeout "
1486 "value %lx\n", timeout);
1487 dump_stack();
1488 current->state = TASK_RUNNING;
1489 goto out;
1490 }
1491 }
1492
1493 expire = timeout + jiffies;
1494
1495 setup_timer_on_stack(&timer, process_timeout, (unsigned long)current);
1496 __mod_timer(&timer, expire, false, TIMER_NOT_PINNED);
1497 schedule();
1498 del_singleshot_timer_sync(&timer);
1499
1500 /* Remove the timer from the object tracker */
1501 destroy_timer_on_stack(&timer);
1502
1503 timeout = expire - jiffies;
1504
1505 out:
1506 return timeout < 0 ? 0 : timeout;
1507}
1508EXPORT_SYMBOL(schedule_timeout);
1509
1510/*
1511 * We can use __set_current_state() here because schedule_timeout() calls
1512 * schedule() unconditionally.
1513 */
1514signed long __sched schedule_timeout_interruptible(signed long timeout)
1515{
1516 __set_current_state(TASK_INTERRUPTIBLE);
1517 return schedule_timeout(timeout);
1518}
1519EXPORT_SYMBOL(schedule_timeout_interruptible);
1520
1521signed long __sched schedule_timeout_killable(signed long timeout)
1522{
1523 __set_current_state(TASK_KILLABLE);
1524 return schedule_timeout(timeout);
1525}
1526EXPORT_SYMBOL(schedule_timeout_killable);
1527
1528signed long __sched schedule_timeout_uninterruptible(signed long timeout)
1529{
1530 __set_current_state(TASK_UNINTERRUPTIBLE);
1531 return schedule_timeout(timeout);
1532}
1533EXPORT_SYMBOL(schedule_timeout_uninterruptible);
1534
1535static int init_timers_cpu(int cpu)
1536{
1537 int j;
1538 struct tvec_base *base;
1539 static char tvec_base_done[NR_CPUS];
1540
1541 if (!tvec_base_done[cpu]) {
1542 static char boot_done;
1543
1544 if (boot_done) {
1545 /*
1546 * The APs use this path later in boot
1547 */
1548 base = kzalloc_node(sizeof(*base), GFP_KERNEL,
1549 cpu_to_node(cpu));
1550 if (!base)
1551 return -ENOMEM;
1552
1553 /* Make sure tvec_base has TIMER_FLAG_MASK bits free */
1554 if (WARN_ON(base != tbase_get_base(base))) {
1555 kfree(base);
1556 return -ENOMEM;
1557 }
1558 per_cpu(tvec_bases, cpu) = base;
1559 } else {
1560 /*
1561 * This is for the boot CPU - we use compile-time
1562 * static initialisation because per-cpu memory isn't
1563 * ready yet and because the memory allocators are not
1564 * initialised either.
1565 */
1566 boot_done = 1;
1567 base = &boot_tvec_bases;
1568 }
1569 spin_lock_init(&base->lock);
1570 tvec_base_done[cpu] = 1;
1571 } else {
1572 base = per_cpu(tvec_bases, cpu);
1573 }
1574
1575
1576 for (j = 0; j < TVN_SIZE; j++) {
1577 INIT_LIST_HEAD(base->tv5.vec + j);
1578 INIT_LIST_HEAD(base->tv4.vec + j);
1579 INIT_LIST_HEAD(base->tv3.vec + j);
1580 INIT_LIST_HEAD(base->tv2.vec + j);
1581 }
1582 for (j = 0; j < TVR_SIZE; j++)
1583 INIT_LIST_HEAD(base->tv1.vec + j);
1584
1585 base->timer_jiffies = jiffies;
1586 base->next_timer = base->timer_jiffies;
1587 base->active_timers = 0;
1588 base->all_timers = 0;
1589 return 0;
1590}
1591
1592#ifdef CONFIG_HOTPLUG_CPU
1593static void migrate_timer_list(struct tvec_base *new_base, struct list_head *head)
1594{
1595 struct timer_list *timer;
1596
1597 while (!list_empty(head)) {
1598 timer = list_first_entry(head, struct timer_list, entry);
1599 /* We ignore the accounting on the dying cpu */
1600 detach_timer(timer, false);
1601 timer_set_base(timer, new_base);
1602 internal_add_timer(new_base, timer);
1603 }
1604}
1605
1606static void migrate_timers(int cpu)
1607{
1608 struct tvec_base *old_base;
1609 struct tvec_base *new_base;
1610 int i;
1611
1612 BUG_ON(cpu_online(cpu));
1613 old_base = per_cpu(tvec_bases, cpu);
1614 new_base = get_cpu_var(tvec_bases);
1615 /*
1616 * The caller is globally serialized and nobody else
1617 * takes two locks at once, deadlock is not possible.
1618 */
1619 spin_lock_irq(&new_base->lock);
1620 spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING);
1621
1622 BUG_ON(old_base->running_timer);
1623
1624 for (i = 0; i < TVR_SIZE; i++)
1625 migrate_timer_list(new_base, old_base->tv1.vec + i);
1626 for (i = 0; i < TVN_SIZE; i++) {
1627 migrate_timer_list(new_base, old_base->tv2.vec + i);
1628 migrate_timer_list(new_base, old_base->tv3.vec + i);
1629 migrate_timer_list(new_base, old_base->tv4.vec + i);
1630 migrate_timer_list(new_base, old_base->tv5.vec + i);
1631 }
1632
1633 spin_unlock(&old_base->lock);
1634 spin_unlock_irq(&new_base->lock);
1635 put_cpu_var(tvec_bases);
1636}
1637#endif /* CONFIG_HOTPLUG_CPU */
1638
1639static int timer_cpu_notify(struct notifier_block *self,
1640 unsigned long action, void *hcpu)
1641{
1642 long cpu = (long)hcpu;
1643 int err;
1644
1645 switch(action) {
1646 case CPU_UP_PREPARE:
1647 case CPU_UP_PREPARE_FROZEN:
1648 err = init_timers_cpu(cpu);
1649 if (err < 0)
1650 return notifier_from_errno(err);
1651 break;
1652#ifdef CONFIG_HOTPLUG_CPU
1653 case CPU_DEAD:
1654 case CPU_DEAD_FROZEN:
1655 migrate_timers(cpu);
1656 break;
1657#endif
1658 default:
1659 break;
1660 }
1661 return NOTIFY_OK;
1662}
1663
1664static struct notifier_block timers_nb = {
1665 .notifier_call = timer_cpu_notify,
1666};
1667
1668
1669void __init init_timers(void)
1670{
1671 int err;
1672
1673 /* ensure there are enough low bits for flags in timer->base pointer */
1674 BUILD_BUG_ON(__alignof__(struct tvec_base) & TIMER_FLAG_MASK);
1675
1676 err = timer_cpu_notify(&timers_nb, (unsigned long)CPU_UP_PREPARE,
1677 (void *)(long)smp_processor_id());
1678 BUG_ON(err != NOTIFY_OK);
1679
1680 init_timer_stats();
1681 register_cpu_notifier(&timers_nb);
1682 open_softirq(TIMER_SOFTIRQ, run_timer_softirq);
1683}
1684
1685/**
1686 * msleep - sleep safely even with waitqueue interruptions
1687 * @msecs: Time in milliseconds to sleep for
1688 */
1689void msleep(unsigned int msecs)
1690{
1691 unsigned long timeout = msecs_to_jiffies(msecs) + 1;
1692
1693 while (timeout)
1694 timeout = schedule_timeout_uninterruptible(timeout);
1695}
1696
1697EXPORT_SYMBOL(msleep);
1698
1699/**
1700 * msleep_interruptible - sleep waiting for signals
1701 * @msecs: Time in milliseconds to sleep for
1702 */
1703unsigned long msleep_interruptible(unsigned int msecs)
1704{
1705 unsigned long timeout = msecs_to_jiffies(msecs) + 1;
1706
1707 while (timeout && !signal_pending(current))
1708 timeout = schedule_timeout_interruptible(timeout);
1709 return jiffies_to_msecs(timeout);
1710}
1711
1712EXPORT_SYMBOL(msleep_interruptible);
1713
1714static int __sched do_usleep_range(unsigned long min, unsigned long max)
1715{
1716 ktime_t kmin;
1717 unsigned long delta;
1718
1719 kmin = ktime_set(0, min * NSEC_PER_USEC);
1720 delta = (max - min) * NSEC_PER_USEC;
1721 return schedule_hrtimeout_range(&kmin, delta, HRTIMER_MODE_REL);
1722}
1723
1724/**
1725 * usleep_range - Drop in replacement for udelay where wakeup is flexible
1726 * @min: Minimum time in usecs to sleep
1727 * @max: Maximum time in usecs to sleep
1728 */
1729void usleep_range(unsigned long min, unsigned long max)
1730{
1731 __set_current_state(TASK_UNINTERRUPTIBLE);
1732 do_usleep_range(min, max);
1733}
1734EXPORT_SYMBOL(usleep_range);
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
53u64 jiffies_64 __cacheline_aligned_in_smp = INITIAL_JIFFIES;
54
55EXPORT_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
67struct tvec {
68 struct list_head vec[TVN_SIZE];
69};
70
71struct tvec_root {
72 struct list_head vec[TVR_SIZE];
73};
74
75struct 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
87struct tvec_base boot_tvec_bases;
88EXPORT_SYMBOL(boot_tvec_bases);
89static DEFINE_PER_CPU(struct tvec_base *, tvec_bases) = &boot_tvec_bases;
90
91/* Functions below help us manage 'deferrable' flag */
92static inline unsigned int tbase_get_deferrable(struct tvec_base *base)
93{
94 return ((unsigned int)(unsigned long)base & TBASE_DEFERRABLE_FLAG);
95}
96
97static 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
102static inline void timer_set_deferrable(struct timer_list *timer)
103{
104 timer->base = TBASE_MAKE_DEFERRED(timer->base);
105}
106
107static inline void
108timer_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
114static 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 */
172unsigned long __round_jiffies(unsigned long j, int cpu)
173{
174 return round_jiffies_common(j, cpu, false);
175}
176EXPORT_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 */
198unsigned 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}
205EXPORT_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 */
222unsigned long round_jiffies(unsigned long j)
223{
224 return round_jiffies_common(j, raw_smp_processor_id(), false);
225}
226EXPORT_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 */
243unsigned long round_jiffies_relative(unsigned long j)
244{
245 return __round_jiffies_relative(j, raw_smp_processor_id());
246}
247EXPORT_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 */
259unsigned long __round_jiffies_up(unsigned long j, int cpu)
260{
261 return round_jiffies_common(j, cpu, true);
262}
263EXPORT_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 */
275unsigned 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}
282EXPORT_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 */
293unsigned long round_jiffies_up(unsigned long j)
294{
295 return round_jiffies_common(j, raw_smp_processor_id(), true);
296}
297EXPORT_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 */
308unsigned long round_jiffies_up_relative(unsigned long j)
309{
310 return __round_jiffies_up_relative(j, raw_smp_processor_id());
311}
312EXPORT_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 */
327void set_timer_slack(struct timer_list *timer, int slack_hz)
328{
329 timer->slack = slack_hz;
330}
331EXPORT_SYMBOL_GPL(set_timer_slack);
332
333static 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
376void __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
386static 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
400static void timer_stats_account_timer(struct timer_list *timer) {}
401#endif
402
403#ifdef CONFIG_DEBUG_OBJECTS_TIMERS
404
405static struct debug_obj_descr timer_debug_descr;
406
407static 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 */
416static 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. */
431static 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 */
441static 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 */
476static 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 */
494static 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
517static 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
526static inline void debug_timer_init(struct timer_list *timer)
527{
528 debug_object_init(timer, &timer_debug_descr);
529}
530
531static inline void debug_timer_activate(struct timer_list *timer)
532{
533 debug_object_activate(timer, &timer_debug_descr);
534}
535
536static inline void debug_timer_deactivate(struct timer_list *timer)
537{
538 debug_object_deactivate(timer, &timer_debug_descr);
539}
540
541static inline void debug_timer_free(struct timer_list *timer)
542{
543 debug_object_free(timer, &timer_debug_descr);
544}
545
546static inline void debug_timer_assert_init(struct timer_list *timer)
547{
548 debug_object_assert_init(timer, &timer_debug_descr);
549}
550
551static void __init_timer(struct timer_list *timer,
552 const char *name,
553 struct lock_class_key *key);
554
555void 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}
562EXPORT_SYMBOL_GPL(init_timer_on_stack_key);
563
564void destroy_timer_on_stack(struct timer_list *timer)
565{
566 debug_object_free(timer, &timer_debug_descr);
567}
568EXPORT_SYMBOL_GPL(destroy_timer_on_stack);
569
570#else
571static inline void debug_timer_init(struct timer_list *timer) { }
572static inline void debug_timer_activate(struct timer_list *timer) { }
573static inline void debug_timer_deactivate(struct timer_list *timer) { }
574static inline void debug_timer_assert_init(struct timer_list *timer) { }
575#endif
576
577static inline void debug_init(struct timer_list *timer)
578{
579 debug_timer_init(timer);
580 trace_timer_init(timer);
581}
582
583static inline void
584debug_activate(struct timer_list *timer, unsigned long expires)
585{
586 debug_timer_activate(timer);
587 trace_timer_start(timer, expires);
588}
589
590static inline void debug_deactivate(struct timer_list *timer)
591{
592 debug_timer_deactivate(timer);
593 trace_timer_cancel(timer);
594}
595
596static inline void debug_assert_init(struct timer_list *timer)
597{
598 debug_timer_assert_init(timer);
599}
600
601static 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
616void 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}
627EXPORT_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 */
639void 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}
646EXPORT_SYMBOL(init_timer_key);
647
648void 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}
655EXPORT_SYMBOL(init_timer_deferrable_key);
656
657static 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 */
682static 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
702static 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
760out_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 */
776int mod_timer_pending(struct timer_list *timer, unsigned long expires)
777{
778 return __mod_timer(timer, expires, true, TIMER_NOT_PINNED);
779}
780EXPORT_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 */
792static inline
793unsigned 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 */
841int 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}
855EXPORT_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 to ensure that the timer is scheduled on the current CPU.
865 *
866 * Note that this does not prevent the timer from being migrated
867 * when the current CPU goes offline. If this is a problem for
868 * you, use CPU-hotplug notifiers to handle it correctly, for
869 * example, cancelling the timer when the corresponding CPU goes
870 * offline.
871 *
872 * mod_timer_pinned(timer, expires) is equivalent to:
873 *
874 * del_timer(timer); timer->expires = expires; add_timer(timer);
875 */
876int mod_timer_pinned(struct timer_list *timer, unsigned long expires)
877{
878 if (timer->expires == expires && timer_pending(timer))
879 return 1;
880
881 return __mod_timer(timer, expires, false, TIMER_PINNED);
882}
883EXPORT_SYMBOL(mod_timer_pinned);
884
885/**
886 * add_timer - start a timer
887 * @timer: the timer to be added
888 *
889 * The kernel will do a ->function(->data) callback from the
890 * timer interrupt at the ->expires point in the future. The
891 * current time is 'jiffies'.
892 *
893 * The timer's ->expires, ->function (and if the handler uses it, ->data)
894 * fields must be set prior calling this function.
895 *
896 * Timers with an ->expires field in the past will be executed in the next
897 * timer tick.
898 */
899void add_timer(struct timer_list *timer)
900{
901 BUG_ON(timer_pending(timer));
902 mod_timer(timer, timer->expires);
903}
904EXPORT_SYMBOL(add_timer);
905
906/**
907 * add_timer_on - start a timer on a particular CPU
908 * @timer: the timer to be added
909 * @cpu: the CPU to start it on
910 *
911 * This is not very scalable on SMP. Double adds are not possible.
912 */
913void add_timer_on(struct timer_list *timer, int cpu)
914{
915 struct tvec_base *base = per_cpu(tvec_bases, cpu);
916 unsigned long flags;
917
918 timer_stats_timer_set_start_info(timer);
919 BUG_ON(timer_pending(timer) || !timer->function);
920 spin_lock_irqsave(&base->lock, flags);
921 timer_set_base(timer, base);
922 debug_activate(timer, timer->expires);
923 if (time_before(timer->expires, base->next_timer) &&
924 !tbase_get_deferrable(timer->base))
925 base->next_timer = timer->expires;
926 internal_add_timer(base, timer);
927 /*
928 * Check whether the other CPU is idle and needs to be
929 * triggered to reevaluate the timer wheel when nohz is
930 * active. We are protected against the other CPU fiddling
931 * with the timer by holding the timer base lock. This also
932 * makes sure that a CPU on the way to idle can not evaluate
933 * the timer wheel.
934 */
935 wake_up_idle_cpu(cpu);
936 spin_unlock_irqrestore(&base->lock, flags);
937}
938EXPORT_SYMBOL_GPL(add_timer_on);
939
940/**
941 * del_timer - deactive a timer.
942 * @timer: the timer to be deactivated
943 *
944 * del_timer() deactivates a timer - this works on both active and inactive
945 * timers.
946 *
947 * The function returns whether it has deactivated a pending timer or not.
948 * (ie. del_timer() of an inactive timer returns 0, del_timer() of an
949 * active timer returns 1.)
950 */
951int del_timer(struct timer_list *timer)
952{
953 struct tvec_base *base;
954 unsigned long flags;
955 int ret = 0;
956
957 debug_assert_init(timer);
958
959 timer_stats_timer_clear_start_info(timer);
960 if (timer_pending(timer)) {
961 base = lock_timer_base(timer, &flags);
962 if (timer_pending(timer)) {
963 detach_timer(timer, 1);
964 if (timer->expires == base->next_timer &&
965 !tbase_get_deferrable(timer->base))
966 base->next_timer = base->timer_jiffies;
967 ret = 1;
968 }
969 spin_unlock_irqrestore(&base->lock, flags);
970 }
971
972 return ret;
973}
974EXPORT_SYMBOL(del_timer);
975
976/**
977 * try_to_del_timer_sync - Try to deactivate a timer
978 * @timer: timer do del
979 *
980 * This function tries to deactivate a timer. Upon successful (ret >= 0)
981 * exit the timer is not queued and the handler is not running on any CPU.
982 */
983int try_to_del_timer_sync(struct timer_list *timer)
984{
985 struct tvec_base *base;
986 unsigned long flags;
987 int ret = -1;
988
989 debug_assert_init(timer);
990
991 base = lock_timer_base(timer, &flags);
992
993 if (base->running_timer == timer)
994 goto out;
995
996 timer_stats_timer_clear_start_info(timer);
997 ret = 0;
998 if (timer_pending(timer)) {
999 detach_timer(timer, 1);
1000 if (timer->expires == base->next_timer &&
1001 !tbase_get_deferrable(timer->base))
1002 base->next_timer = base->timer_jiffies;
1003 ret = 1;
1004 }
1005out:
1006 spin_unlock_irqrestore(&base->lock, flags);
1007
1008 return ret;
1009}
1010EXPORT_SYMBOL(try_to_del_timer_sync);
1011
1012#ifdef CONFIG_SMP
1013/**
1014 * del_timer_sync - deactivate a timer and wait for the handler to finish.
1015 * @timer: the timer to be deactivated
1016 *
1017 * This function only differs from del_timer() on SMP: besides deactivating
1018 * the timer it also makes sure the handler has finished executing on other
1019 * CPUs.
1020 *
1021 * Synchronization rules: Callers must prevent restarting of the timer,
1022 * otherwise this function is meaningless. It must not be called from
1023 * interrupt contexts. The caller must not hold locks which would prevent
1024 * completion of the timer's handler. The timer's handler must not call
1025 * add_timer_on(). Upon exit the timer is not queued and the handler is
1026 * not running on any CPU.
1027 *
1028 * Note: You must not hold locks that are held in interrupt context
1029 * while calling this function. Even if the lock has nothing to do
1030 * with the timer in question. Here's why:
1031 *
1032 * CPU0 CPU1
1033 * ---- ----
1034 * <SOFTIRQ>
1035 * call_timer_fn();
1036 * base->running_timer = mytimer;
1037 * spin_lock_irq(somelock);
1038 * <IRQ>
1039 * spin_lock(somelock);
1040 * del_timer_sync(mytimer);
1041 * while (base->running_timer == mytimer);
1042 *
1043 * Now del_timer_sync() will never return and never release somelock.
1044 * The interrupt on the other CPU is waiting to grab somelock but
1045 * it has interrupted the softirq that CPU0 is waiting to finish.
1046 *
1047 * The function returns whether it has deactivated a pending timer or not.
1048 */
1049int del_timer_sync(struct timer_list *timer)
1050{
1051#ifdef CONFIG_LOCKDEP
1052 unsigned long flags;
1053
1054 /*
1055 * If lockdep gives a backtrace here, please reference
1056 * the synchronization rules above.
1057 */
1058 local_irq_save(flags);
1059 lock_map_acquire(&timer->lockdep_map);
1060 lock_map_release(&timer->lockdep_map);
1061 local_irq_restore(flags);
1062#endif
1063 /*
1064 * don't use it in hardirq context, because it
1065 * could lead to deadlock.
1066 */
1067 WARN_ON(in_irq());
1068 for (;;) {
1069 int ret = try_to_del_timer_sync(timer);
1070 if (ret >= 0)
1071 return ret;
1072 cpu_relax();
1073 }
1074}
1075EXPORT_SYMBOL(del_timer_sync);
1076#endif
1077
1078static int cascade(struct tvec_base *base, struct tvec *tv, int index)
1079{
1080 /* cascade all the timers from tv up one level */
1081 struct timer_list *timer, *tmp;
1082 struct list_head tv_list;
1083
1084 list_replace_init(tv->vec + index, &tv_list);
1085
1086 /*
1087 * We are removing _all_ timers from the list, so we
1088 * don't have to detach them individually.
1089 */
1090 list_for_each_entry_safe(timer, tmp, &tv_list, entry) {
1091 BUG_ON(tbase_get_base(timer->base) != base);
1092 internal_add_timer(base, timer);
1093 }
1094
1095 return index;
1096}
1097
1098static void call_timer_fn(struct timer_list *timer, void (*fn)(unsigned long),
1099 unsigned long data)
1100{
1101 int preempt_count = preempt_count();
1102
1103#ifdef CONFIG_LOCKDEP
1104 /*
1105 * It is permissible to free the timer from inside the
1106 * function that is called from it, this we need to take into
1107 * account for lockdep too. To avoid bogus "held lock freed"
1108 * warnings as well as problems when looking into
1109 * timer->lockdep_map, make a copy and use that here.
1110 */
1111 struct lockdep_map lockdep_map;
1112
1113 lockdep_copy_map(&lockdep_map, &timer->lockdep_map);
1114#endif
1115 /*
1116 * Couple the lock chain with the lock chain at
1117 * del_timer_sync() by acquiring the lock_map around the fn()
1118 * call here and in del_timer_sync().
1119 */
1120 lock_map_acquire(&lockdep_map);
1121
1122 trace_timer_expire_entry(timer);
1123 fn(data);
1124 trace_timer_expire_exit(timer);
1125
1126 lock_map_release(&lockdep_map);
1127
1128 if (preempt_count != preempt_count()) {
1129 WARN_ONCE(1, "timer: %pF preempt leak: %08x -> %08x\n",
1130 fn, preempt_count, preempt_count());
1131 /*
1132 * Restore the preempt count. That gives us a decent
1133 * chance to survive and extract information. If the
1134 * callback kept a lock held, bad luck, but not worse
1135 * than the BUG() we had.
1136 */
1137 preempt_count() = preempt_count;
1138 }
1139}
1140
1141#define INDEX(N) ((base->timer_jiffies >> (TVR_BITS + (N) * TVN_BITS)) & TVN_MASK)
1142
1143/**
1144 * __run_timers - run all expired timers (if any) on this CPU.
1145 * @base: the timer vector to be processed.
1146 *
1147 * This function cascades all vectors and executes all expired timer
1148 * vectors.
1149 */
1150static inline void __run_timers(struct tvec_base *base)
1151{
1152 struct timer_list *timer;
1153
1154 spin_lock_irq(&base->lock);
1155 while (time_after_eq(jiffies, base->timer_jiffies)) {
1156 struct list_head work_list;
1157 struct list_head *head = &work_list;
1158 int index = base->timer_jiffies & TVR_MASK;
1159
1160 /*
1161 * Cascade timers:
1162 */
1163 if (!index &&
1164 (!cascade(base, &base->tv2, INDEX(0))) &&
1165 (!cascade(base, &base->tv3, INDEX(1))) &&
1166 !cascade(base, &base->tv4, INDEX(2)))
1167 cascade(base, &base->tv5, INDEX(3));
1168 ++base->timer_jiffies;
1169 list_replace_init(base->tv1.vec + index, &work_list);
1170 while (!list_empty(head)) {
1171 void (*fn)(unsigned long);
1172 unsigned long data;
1173
1174 timer = list_first_entry(head, struct timer_list,entry);
1175 fn = timer->function;
1176 data = timer->data;
1177
1178 timer_stats_account_timer(timer);
1179
1180 base->running_timer = timer;
1181 detach_timer(timer, 1);
1182
1183 spin_unlock_irq(&base->lock);
1184 call_timer_fn(timer, fn, data);
1185 spin_lock_irq(&base->lock);
1186 }
1187 }
1188 base->running_timer = NULL;
1189 spin_unlock_irq(&base->lock);
1190}
1191
1192#ifdef CONFIG_NO_HZ
1193/*
1194 * Find out when the next timer event is due to happen. This
1195 * is used on S/390 to stop all activity when a CPU is idle.
1196 * This function needs to be called with interrupts disabled.
1197 */
1198static unsigned long __next_timer_interrupt(struct tvec_base *base)
1199{
1200 unsigned long timer_jiffies = base->timer_jiffies;
1201 unsigned long expires = timer_jiffies + NEXT_TIMER_MAX_DELTA;
1202 int index, slot, array, found = 0;
1203 struct timer_list *nte;
1204 struct tvec *varray[4];
1205
1206 /* Look for timer events in tv1. */
1207 index = slot = timer_jiffies & TVR_MASK;
1208 do {
1209 list_for_each_entry(nte, base->tv1.vec + slot, entry) {
1210 if (tbase_get_deferrable(nte->base))
1211 continue;
1212
1213 found = 1;
1214 expires = nte->expires;
1215 /* Look at the cascade bucket(s)? */
1216 if (!index || slot < index)
1217 goto cascade;
1218 return expires;
1219 }
1220 slot = (slot + 1) & TVR_MASK;
1221 } while (slot != index);
1222
1223cascade:
1224 /* Calculate the next cascade event */
1225 if (index)
1226 timer_jiffies += TVR_SIZE - index;
1227 timer_jiffies >>= TVR_BITS;
1228
1229 /* Check tv2-tv5. */
1230 varray[0] = &base->tv2;
1231 varray[1] = &base->tv3;
1232 varray[2] = &base->tv4;
1233 varray[3] = &base->tv5;
1234
1235 for (array = 0; array < 4; array++) {
1236 struct tvec *varp = varray[array];
1237
1238 index = slot = timer_jiffies & TVN_MASK;
1239 do {
1240 list_for_each_entry(nte, varp->vec + slot, entry) {
1241 if (tbase_get_deferrable(nte->base))
1242 continue;
1243
1244 found = 1;
1245 if (time_before(nte->expires, expires))
1246 expires = nte->expires;
1247 }
1248 /*
1249 * Do we still search for the first timer or are
1250 * we looking up the cascade buckets ?
1251 */
1252 if (found) {
1253 /* Look at the cascade bucket(s)? */
1254 if (!index || slot < index)
1255 break;
1256 return expires;
1257 }
1258 slot = (slot + 1) & TVN_MASK;
1259 } while (slot != index);
1260
1261 if (index)
1262 timer_jiffies += TVN_SIZE - index;
1263 timer_jiffies >>= TVN_BITS;
1264 }
1265 return expires;
1266}
1267
1268/*
1269 * Check, if the next hrtimer event is before the next timer wheel
1270 * event:
1271 */
1272static unsigned long cmp_next_hrtimer_event(unsigned long now,
1273 unsigned long expires)
1274{
1275 ktime_t hr_delta = hrtimer_get_next_event();
1276 struct timespec tsdelta;
1277 unsigned long delta;
1278
1279 if (hr_delta.tv64 == KTIME_MAX)
1280 return expires;
1281
1282 /*
1283 * Expired timer available, let it expire in the next tick
1284 */
1285 if (hr_delta.tv64 <= 0)
1286 return now + 1;
1287
1288 tsdelta = ktime_to_timespec(hr_delta);
1289 delta = timespec_to_jiffies(&tsdelta);
1290
1291 /*
1292 * Limit the delta to the max value, which is checked in
1293 * tick_nohz_stop_sched_tick():
1294 */
1295 if (delta > NEXT_TIMER_MAX_DELTA)
1296 delta = NEXT_TIMER_MAX_DELTA;
1297
1298 /*
1299 * Take rounding errors in to account and make sure, that it
1300 * expires in the next tick. Otherwise we go into an endless
1301 * ping pong due to tick_nohz_stop_sched_tick() retriggering
1302 * the timer softirq
1303 */
1304 if (delta < 1)
1305 delta = 1;
1306 now += delta;
1307 if (time_before(now, expires))
1308 return now;
1309 return expires;
1310}
1311
1312/**
1313 * get_next_timer_interrupt - return the jiffy of the next pending timer
1314 * @now: current time (in jiffies)
1315 */
1316unsigned long get_next_timer_interrupt(unsigned long now)
1317{
1318 struct tvec_base *base = __this_cpu_read(tvec_bases);
1319 unsigned long expires;
1320
1321 /*
1322 * Pretend that there is no timer pending if the cpu is offline.
1323 * Possible pending timers will be migrated later to an active cpu.
1324 */
1325 if (cpu_is_offline(smp_processor_id()))
1326 return now + NEXT_TIMER_MAX_DELTA;
1327 spin_lock(&base->lock);
1328 if (time_before_eq(base->next_timer, base->timer_jiffies))
1329 base->next_timer = __next_timer_interrupt(base);
1330 expires = base->next_timer;
1331 spin_unlock(&base->lock);
1332
1333 if (time_before_eq(expires, now))
1334 return now;
1335
1336 return cmp_next_hrtimer_event(now, expires);
1337}
1338#endif
1339
1340/*
1341 * Called from the timer interrupt handler to charge one tick to the current
1342 * process. user_tick is 1 if the tick is user time, 0 for system.
1343 */
1344void update_process_times(int user_tick)
1345{
1346 struct task_struct *p = current;
1347 int cpu = smp_processor_id();
1348
1349 /* Note: this timer irq context must be accounted for as well. */
1350 account_process_tick(p, user_tick);
1351 run_local_timers();
1352 rcu_check_callbacks(cpu, user_tick);
1353 printk_tick();
1354#ifdef CONFIG_IRQ_WORK
1355 if (in_irq())
1356 irq_work_run();
1357#endif
1358 scheduler_tick();
1359 run_posix_cpu_timers(p);
1360}
1361
1362/*
1363 * This function runs timers and the timer-tq in bottom half context.
1364 */
1365static void run_timer_softirq(struct softirq_action *h)
1366{
1367 struct tvec_base *base = __this_cpu_read(tvec_bases);
1368
1369 hrtimer_run_pending();
1370
1371 if (time_after_eq(jiffies, base->timer_jiffies))
1372 __run_timers(base);
1373}
1374
1375/*
1376 * Called by the local, per-CPU timer interrupt on SMP.
1377 */
1378void run_local_timers(void)
1379{
1380 hrtimer_run_queues();
1381 raise_softirq(TIMER_SOFTIRQ);
1382}
1383
1384#ifdef __ARCH_WANT_SYS_ALARM
1385
1386/*
1387 * For backwards compatibility? This can be done in libc so Alpha
1388 * and all newer ports shouldn't need it.
1389 */
1390SYSCALL_DEFINE1(alarm, unsigned int, seconds)
1391{
1392 return alarm_setitimer(seconds);
1393}
1394
1395#endif
1396
1397#ifndef __alpha__
1398
1399/*
1400 * The Alpha uses getxpid, getxuid, and getxgid instead. Maybe this
1401 * should be moved into arch/i386 instead?
1402 */
1403
1404/**
1405 * sys_getpid - return the thread group id of the current process
1406 *
1407 * Note, despite the name, this returns the tgid not the pid. The tgid and
1408 * the pid are identical unless CLONE_THREAD was specified on clone() in
1409 * which case the tgid is the same in all threads of the same group.
1410 *
1411 * This is SMP safe as current->tgid does not change.
1412 */
1413SYSCALL_DEFINE0(getpid)
1414{
1415 return task_tgid_vnr(current);
1416}
1417
1418/*
1419 * Accessing ->real_parent is not SMP-safe, it could
1420 * change from under us. However, we can use a stale
1421 * value of ->real_parent under rcu_read_lock(), see
1422 * release_task()->call_rcu(delayed_put_task_struct).
1423 */
1424SYSCALL_DEFINE0(getppid)
1425{
1426 int pid;
1427
1428 rcu_read_lock();
1429 pid = task_tgid_vnr(rcu_dereference(current->real_parent));
1430 rcu_read_unlock();
1431
1432 return pid;
1433}
1434
1435SYSCALL_DEFINE0(getuid)
1436{
1437 /* Only we change this so SMP safe */
1438 return from_kuid_munged(current_user_ns(), current_uid());
1439}
1440
1441SYSCALL_DEFINE0(geteuid)
1442{
1443 /* Only we change this so SMP safe */
1444 return from_kuid_munged(current_user_ns(), current_euid());
1445}
1446
1447SYSCALL_DEFINE0(getgid)
1448{
1449 /* Only we change this so SMP safe */
1450 return from_kgid_munged(current_user_ns(), current_gid());
1451}
1452
1453SYSCALL_DEFINE0(getegid)
1454{
1455 /* Only we change this so SMP safe */
1456 return from_kgid_munged(current_user_ns(), current_egid());
1457}
1458
1459#endif
1460
1461static void process_timeout(unsigned long __data)
1462{
1463 wake_up_process((struct task_struct *)__data);
1464}
1465
1466/**
1467 * schedule_timeout - sleep until timeout
1468 * @timeout: timeout value in jiffies
1469 *
1470 * Make the current task sleep until @timeout jiffies have
1471 * elapsed. The routine will return immediately unless
1472 * the current task state has been set (see set_current_state()).
1473 *
1474 * You can set the task state as follows -
1475 *
1476 * %TASK_UNINTERRUPTIBLE - at least @timeout jiffies are guaranteed to
1477 * pass before the routine returns. The routine will return 0
1478 *
1479 * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
1480 * delivered to the current task. In this case the remaining time
1481 * in jiffies will be returned, or 0 if the timer expired in time
1482 *
1483 * The current task state is guaranteed to be TASK_RUNNING when this
1484 * routine returns.
1485 *
1486 * Specifying a @timeout value of %MAX_SCHEDULE_TIMEOUT will schedule
1487 * the CPU away without a bound on the timeout. In this case the return
1488 * value will be %MAX_SCHEDULE_TIMEOUT.
1489 *
1490 * In all cases the return value is guaranteed to be non-negative.
1491 */
1492signed long __sched schedule_timeout(signed long timeout)
1493{
1494 struct timer_list timer;
1495 unsigned long expire;
1496
1497 switch (timeout)
1498 {
1499 case MAX_SCHEDULE_TIMEOUT:
1500 /*
1501 * These two special cases are useful to be comfortable
1502 * in the caller. Nothing more. We could take
1503 * MAX_SCHEDULE_TIMEOUT from one of the negative value
1504 * but I' d like to return a valid offset (>=0) to allow
1505 * the caller to do everything it want with the retval.
1506 */
1507 schedule();
1508 goto out;
1509 default:
1510 /*
1511 * Another bit of PARANOID. Note that the retval will be
1512 * 0 since no piece of kernel is supposed to do a check
1513 * for a negative retval of schedule_timeout() (since it
1514 * should never happens anyway). You just have the printk()
1515 * that will tell you if something is gone wrong and where.
1516 */
1517 if (timeout < 0) {
1518 printk(KERN_ERR "schedule_timeout: wrong timeout "
1519 "value %lx\n", timeout);
1520 dump_stack();
1521 current->state = TASK_RUNNING;
1522 goto out;
1523 }
1524 }
1525
1526 expire = timeout + jiffies;
1527
1528 setup_timer_on_stack(&timer, process_timeout, (unsigned long)current);
1529 __mod_timer(&timer, expire, false, TIMER_NOT_PINNED);
1530 schedule();
1531 del_singleshot_timer_sync(&timer);
1532
1533 /* Remove the timer from the object tracker */
1534 destroy_timer_on_stack(&timer);
1535
1536 timeout = expire - jiffies;
1537
1538 out:
1539 return timeout < 0 ? 0 : timeout;
1540}
1541EXPORT_SYMBOL(schedule_timeout);
1542
1543/*
1544 * We can use __set_current_state() here because schedule_timeout() calls
1545 * schedule() unconditionally.
1546 */
1547signed long __sched schedule_timeout_interruptible(signed long timeout)
1548{
1549 __set_current_state(TASK_INTERRUPTIBLE);
1550 return schedule_timeout(timeout);
1551}
1552EXPORT_SYMBOL(schedule_timeout_interruptible);
1553
1554signed long __sched schedule_timeout_killable(signed long timeout)
1555{
1556 __set_current_state(TASK_KILLABLE);
1557 return schedule_timeout(timeout);
1558}
1559EXPORT_SYMBOL(schedule_timeout_killable);
1560
1561signed long __sched schedule_timeout_uninterruptible(signed long timeout)
1562{
1563 __set_current_state(TASK_UNINTERRUPTIBLE);
1564 return schedule_timeout(timeout);
1565}
1566EXPORT_SYMBOL(schedule_timeout_uninterruptible);
1567
1568/* Thread ID - the internal kernel "pid" */
1569SYSCALL_DEFINE0(gettid)
1570{
1571 return task_pid_vnr(current);
1572}
1573
1574/**
1575 * do_sysinfo - fill in sysinfo struct
1576 * @info: pointer to buffer to fill
1577 */
1578int do_sysinfo(struct sysinfo *info)
1579{
1580 unsigned long mem_total, sav_total;
1581 unsigned int mem_unit, bitcount;
1582 struct timespec tp;
1583
1584 memset(info, 0, sizeof(struct sysinfo));
1585
1586 ktime_get_ts(&tp);
1587 monotonic_to_bootbased(&tp);
1588 info->uptime = tp.tv_sec + (tp.tv_nsec ? 1 : 0);
1589
1590 get_avenrun(info->loads, 0, SI_LOAD_SHIFT - FSHIFT);
1591
1592 info->procs = nr_threads;
1593
1594 si_meminfo(info);
1595 si_swapinfo(info);
1596
1597 /*
1598 * If the sum of all the available memory (i.e. ram + swap)
1599 * is less than can be stored in a 32 bit unsigned long then
1600 * we can be binary compatible with 2.2.x kernels. If not,
1601 * well, in that case 2.2.x was broken anyways...
1602 *
1603 * -Erik Andersen <andersee@debian.org>
1604 */
1605
1606 mem_total = info->totalram + info->totalswap;
1607 if (mem_total < info->totalram || mem_total < info->totalswap)
1608 goto out;
1609 bitcount = 0;
1610 mem_unit = info->mem_unit;
1611 while (mem_unit > 1) {
1612 bitcount++;
1613 mem_unit >>= 1;
1614 sav_total = mem_total;
1615 mem_total <<= 1;
1616 if (mem_total < sav_total)
1617 goto out;
1618 }
1619
1620 /*
1621 * If mem_total did not overflow, multiply all memory values by
1622 * info->mem_unit and set it to 1. This leaves things compatible
1623 * with 2.2.x, and also retains compatibility with earlier 2.4.x
1624 * kernels...
1625 */
1626
1627 info->mem_unit = 1;
1628 info->totalram <<= bitcount;
1629 info->freeram <<= bitcount;
1630 info->sharedram <<= bitcount;
1631 info->bufferram <<= bitcount;
1632 info->totalswap <<= bitcount;
1633 info->freeswap <<= bitcount;
1634 info->totalhigh <<= bitcount;
1635 info->freehigh <<= bitcount;
1636
1637out:
1638 return 0;
1639}
1640
1641SYSCALL_DEFINE1(sysinfo, struct sysinfo __user *, info)
1642{
1643 struct sysinfo val;
1644
1645 do_sysinfo(&val);
1646
1647 if (copy_to_user(info, &val, sizeof(struct sysinfo)))
1648 return -EFAULT;
1649
1650 return 0;
1651}
1652
1653static int __cpuinit init_timers_cpu(int cpu)
1654{
1655 int j;
1656 struct tvec_base *base;
1657 static char __cpuinitdata tvec_base_done[NR_CPUS];
1658
1659 if (!tvec_base_done[cpu]) {
1660 static char boot_done;
1661
1662 if (boot_done) {
1663 /*
1664 * The APs use this path later in boot
1665 */
1666 base = kmalloc_node(sizeof(*base),
1667 GFP_KERNEL | __GFP_ZERO,
1668 cpu_to_node(cpu));
1669 if (!base)
1670 return -ENOMEM;
1671
1672 /* Make sure that tvec_base is 2 byte aligned */
1673 if (tbase_get_deferrable(base)) {
1674 WARN_ON(1);
1675 kfree(base);
1676 return -ENOMEM;
1677 }
1678 per_cpu(tvec_bases, cpu) = base;
1679 } else {
1680 /*
1681 * This is for the boot CPU - we use compile-time
1682 * static initialisation because per-cpu memory isn't
1683 * ready yet and because the memory allocators are not
1684 * initialised either.
1685 */
1686 boot_done = 1;
1687 base = &boot_tvec_bases;
1688 }
1689 tvec_base_done[cpu] = 1;
1690 } else {
1691 base = per_cpu(tvec_bases, cpu);
1692 }
1693
1694 spin_lock_init(&base->lock);
1695
1696 for (j = 0; j < TVN_SIZE; j++) {
1697 INIT_LIST_HEAD(base->tv5.vec + j);
1698 INIT_LIST_HEAD(base->tv4.vec + j);
1699 INIT_LIST_HEAD(base->tv3.vec + j);
1700 INIT_LIST_HEAD(base->tv2.vec + j);
1701 }
1702 for (j = 0; j < TVR_SIZE; j++)
1703 INIT_LIST_HEAD(base->tv1.vec + j);
1704
1705 base->timer_jiffies = jiffies;
1706 base->next_timer = base->timer_jiffies;
1707 return 0;
1708}
1709
1710#ifdef CONFIG_HOTPLUG_CPU
1711static void migrate_timer_list(struct tvec_base *new_base, struct list_head *head)
1712{
1713 struct timer_list *timer;
1714
1715 while (!list_empty(head)) {
1716 timer = list_first_entry(head, struct timer_list, entry);
1717 detach_timer(timer, 0);
1718 timer_set_base(timer, new_base);
1719 if (time_before(timer->expires, new_base->next_timer) &&
1720 !tbase_get_deferrable(timer->base))
1721 new_base->next_timer = timer->expires;
1722 internal_add_timer(new_base, timer);
1723 }
1724}
1725
1726static void __cpuinit migrate_timers(int cpu)
1727{
1728 struct tvec_base *old_base;
1729 struct tvec_base *new_base;
1730 int i;
1731
1732 BUG_ON(cpu_online(cpu));
1733 old_base = per_cpu(tvec_bases, cpu);
1734 new_base = get_cpu_var(tvec_bases);
1735 /*
1736 * The caller is globally serialized and nobody else
1737 * takes two locks at once, deadlock is not possible.
1738 */
1739 spin_lock_irq(&new_base->lock);
1740 spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING);
1741
1742 BUG_ON(old_base->running_timer);
1743
1744 for (i = 0; i < TVR_SIZE; i++)
1745 migrate_timer_list(new_base, old_base->tv1.vec + i);
1746 for (i = 0; i < TVN_SIZE; i++) {
1747 migrate_timer_list(new_base, old_base->tv2.vec + i);
1748 migrate_timer_list(new_base, old_base->tv3.vec + i);
1749 migrate_timer_list(new_base, old_base->tv4.vec + i);
1750 migrate_timer_list(new_base, old_base->tv5.vec + i);
1751 }
1752
1753 spin_unlock(&old_base->lock);
1754 spin_unlock_irq(&new_base->lock);
1755 put_cpu_var(tvec_bases);
1756}
1757#endif /* CONFIG_HOTPLUG_CPU */
1758
1759static int __cpuinit timer_cpu_notify(struct notifier_block *self,
1760 unsigned long action, void *hcpu)
1761{
1762 long cpu = (long)hcpu;
1763 int err;
1764
1765 switch(action) {
1766 case CPU_UP_PREPARE:
1767 case CPU_UP_PREPARE_FROZEN:
1768 err = init_timers_cpu(cpu);
1769 if (err < 0)
1770 return notifier_from_errno(err);
1771 break;
1772#ifdef CONFIG_HOTPLUG_CPU
1773 case CPU_DEAD:
1774 case CPU_DEAD_FROZEN:
1775 migrate_timers(cpu);
1776 break;
1777#endif
1778 default:
1779 break;
1780 }
1781 return NOTIFY_OK;
1782}
1783
1784static struct notifier_block __cpuinitdata timers_nb = {
1785 .notifier_call = timer_cpu_notify,
1786};
1787
1788
1789void __init init_timers(void)
1790{
1791 int err = timer_cpu_notify(&timers_nb, (unsigned long)CPU_UP_PREPARE,
1792 (void *)(long)smp_processor_id());
1793
1794 init_timer_stats();
1795
1796 BUG_ON(err != NOTIFY_OK);
1797 register_cpu_notifier(&timers_nb);
1798 open_softirq(TIMER_SOFTIRQ, run_timer_softirq);
1799}
1800
1801/**
1802 * msleep - sleep safely even with waitqueue interruptions
1803 * @msecs: Time in milliseconds to sleep for
1804 */
1805void msleep(unsigned int msecs)
1806{
1807 unsigned long timeout = msecs_to_jiffies(msecs) + 1;
1808
1809 while (timeout)
1810 timeout = schedule_timeout_uninterruptible(timeout);
1811}
1812
1813EXPORT_SYMBOL(msleep);
1814
1815/**
1816 * msleep_interruptible - sleep waiting for signals
1817 * @msecs: Time in milliseconds to sleep for
1818 */
1819unsigned long msleep_interruptible(unsigned int msecs)
1820{
1821 unsigned long timeout = msecs_to_jiffies(msecs) + 1;
1822
1823 while (timeout && !signal_pending(current))
1824 timeout = schedule_timeout_interruptible(timeout);
1825 return jiffies_to_msecs(timeout);
1826}
1827
1828EXPORT_SYMBOL(msleep_interruptible);
1829
1830static int __sched do_usleep_range(unsigned long min, unsigned long max)
1831{
1832 ktime_t kmin;
1833 unsigned long delta;
1834
1835 kmin = ktime_set(0, min * NSEC_PER_USEC);
1836 delta = (max - min) * NSEC_PER_USEC;
1837 return schedule_hrtimeout_range(&kmin, delta, HRTIMER_MODE_REL);
1838}
1839
1840/**
1841 * usleep_range - Drop in replacement for udelay where wakeup is flexible
1842 * @min: Minimum time in usecs to sleep
1843 * @max: Maximum time in usecs to sleep
1844 */
1845void usleep_range(unsigned long min, unsigned long max)
1846{
1847 __set_current_state(TASK_UNINTERRUPTIBLE);
1848 do_usleep_range(min, max);
1849}
1850EXPORT_SYMBOL(usleep_range);