2 * linux/kernel/hrtimer.c
4 * Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de>
5 * Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
6 * Copyright(C) 2006-2007 Timesys Corp., Thomas Gleixner
8 * High-resolution kernel timers
10 * In contrast to the low-resolution timeout API implemented in
11 * kernel/timer.c, hrtimers provide finer resolution and accuracy
12 * depending on system configuration and capabilities.
14 * These timers are currently used for:
18 * - precise in-kernel timing
20 * Started by: Thomas Gleixner and Ingo Molnar
23 * based on kernel/timer.c
25 * Help, testing, suggestions, bugfixes, improvements were
28 * George Anzinger, Andrew Morton, Steven Rostedt, Roman Zippel
31 * For licencing details see kernel-base/COPYING
34 #include <linux/cpu.h>
35 #include <linux/export.h>
36 #include <linux/percpu.h>
37 #include <linux/hrtimer.h>
38 #include <linux/notifier.h>
39 #include <linux/syscalls.h>
40 #include <linux/kallsyms.h>
41 #include <linux/interrupt.h>
42 #include <linux/tick.h>
43 #include <linux/seq_file.h>
44 #include <linux/err.h>
45 #include <linux/debugobjects.h>
46 #include <linux/sched/signal.h>
47 #include <linux/sched/sysctl.h>
48 #include <linux/sched/rt.h>
49 #include <linux/sched/deadline.h>
50 #include <linux/sched/nohz.h>
51 #include <linux/sched/debug.h>
52 #include <linux/timer.h>
53 #include <linux/freezer.h>
54 #include <linux/compat.h>
56 #include <linux/uaccess.h>
58 #include <trace/events/timer.h>
60 #include "tick-internal.h"
65 * There are more clockids than hrtimer bases. Thus, we index
66 * into the timer bases by the hrtimer_base_type enum. When trying
67 * to reach a base using a clockid, hrtimer_clockid_to_base()
68 * is used to convert from clockid to the proper hrtimer_base_type.
70 DEFINE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases) =
72 .lock = __RAW_SPIN_LOCK_UNLOCKED(hrtimer_bases.lock),
73 .seq = SEQCNT_ZERO(hrtimer_bases.seq),
77 .index = HRTIMER_BASE_MONOTONIC,
78 .clockid = CLOCK_MONOTONIC,
79 .get_time = &ktime_get,
82 .index = HRTIMER_BASE_REALTIME,
83 .clockid = CLOCK_REALTIME,
84 .get_time = &ktime_get_real,
87 .index = HRTIMER_BASE_BOOTTIME,
88 .clockid = CLOCK_BOOTTIME,
89 .get_time = &ktime_get_boottime,
92 .index = HRTIMER_BASE_TAI,
94 .get_time = &ktime_get_clocktai,
99 static const int hrtimer_clock_to_base_table[MAX_CLOCKS] = {
100 /* Make sure we catch unsupported clockids */
101 [0 ... MAX_CLOCKS - 1] = HRTIMER_MAX_CLOCK_BASES,
103 [CLOCK_REALTIME] = HRTIMER_BASE_REALTIME,
104 [CLOCK_MONOTONIC] = HRTIMER_BASE_MONOTONIC,
105 [CLOCK_BOOTTIME] = HRTIMER_BASE_BOOTTIME,
106 [CLOCK_TAI] = HRTIMER_BASE_TAI,
110 * Functions and macros which are different for UP/SMP systems are kept in a
116 * We require the migration_base for lock_hrtimer_base()/switch_hrtimer_base()
117 * such that hrtimer_callback_running() can unconditionally dereference
118 * timer->base->cpu_base
120 static struct hrtimer_cpu_base migration_cpu_base = {
121 .seq = SEQCNT_ZERO(migration_cpu_base),
122 .clock_base = { { .cpu_base = &migration_cpu_base, }, },
125 #define migration_base migration_cpu_base.clock_base[0]
128 * We are using hashed locking: holding per_cpu(hrtimer_bases)[n].lock
129 * means that all timers which are tied to this base via timer->base are
130 * locked, and the base itself is locked too.
132 * So __run_timers/migrate_timers can safely modify all timers which could
133 * be found on the lists/queues.
135 * When the timer's base is locked, and the timer removed from list, it is
136 * possible to set timer->base = &migration_base and drop the lock: the timer
140 struct hrtimer_clock_base *lock_hrtimer_base(const struct hrtimer *timer,
141 unsigned long *flags)
143 struct hrtimer_clock_base *base;
147 if (likely(base != &migration_base)) {
148 raw_spin_lock_irqsave(&base->cpu_base->lock, *flags);
149 if (likely(base == timer->base))
151 /* The timer has migrated to another CPU: */
152 raw_spin_unlock_irqrestore(&base->cpu_base->lock, *flags);
159 * With HIGHRES=y we do not migrate the timer when it is expiring
160 * before the next event on the target cpu because we cannot reprogram
161 * the target cpu hardware and we would cause it to fire late.
163 * Called with cpu_base->lock of target cpu held.
166 hrtimer_check_target(struct hrtimer *timer, struct hrtimer_clock_base *new_base)
168 #ifdef CONFIG_HIGH_RES_TIMERS
171 if (!new_base->cpu_base->hres_active)
174 expires = ktime_sub(hrtimer_get_expires(timer), new_base->offset);
175 return expires <= new_base->cpu_base->expires_next;
181 #ifdef CONFIG_NO_HZ_COMMON
183 struct hrtimer_cpu_base *get_target_base(struct hrtimer_cpu_base *base,
186 if (pinned || !base->migration_enabled)
188 return &per_cpu(hrtimer_bases, get_nohz_timer_target());
192 struct hrtimer_cpu_base *get_target_base(struct hrtimer_cpu_base *base,
200 * We switch the timer base to a power-optimized selected CPU target,
202 * - NO_HZ_COMMON is enabled
203 * - timer migration is enabled
204 * - the timer callback is not running
205 * - the timer is not the first expiring timer on the new target
207 * If one of the above requirements is not fulfilled we move the timer
208 * to the current CPU or leave it on the previously assigned CPU if
209 * the timer callback is currently running.
211 static inline struct hrtimer_clock_base *
212 switch_hrtimer_base(struct hrtimer *timer, struct hrtimer_clock_base *base,
215 struct hrtimer_cpu_base *new_cpu_base, *this_cpu_base;
216 struct hrtimer_clock_base *new_base;
217 int basenum = base->index;
219 this_cpu_base = this_cpu_ptr(&hrtimer_bases);
220 new_cpu_base = get_target_base(this_cpu_base, pinned);
222 new_base = &new_cpu_base->clock_base[basenum];
224 if (base != new_base) {
226 * We are trying to move timer to new_base.
227 * However we can't change timer's base while it is running,
228 * so we keep it on the same CPU. No hassle vs. reprogramming
229 * the event source in the high resolution case. The softirq
230 * code will take care of this when the timer function has
231 * completed. There is no conflict as we hold the lock until
232 * the timer is enqueued.
234 if (unlikely(hrtimer_callback_running(timer)))
237 /* See the comment in lock_hrtimer_base() */
238 timer->base = &migration_base;
239 raw_spin_unlock(&base->cpu_base->lock);
240 raw_spin_lock(&new_base->cpu_base->lock);
242 if (new_cpu_base != this_cpu_base &&
243 hrtimer_check_target(timer, new_base)) {
244 raw_spin_unlock(&new_base->cpu_base->lock);
245 raw_spin_lock(&base->cpu_base->lock);
246 new_cpu_base = this_cpu_base;
250 timer->base = new_base;
252 if (new_cpu_base != this_cpu_base &&
253 hrtimer_check_target(timer, new_base)) {
254 new_cpu_base = this_cpu_base;
261 #else /* CONFIG_SMP */
263 static inline struct hrtimer_clock_base *
264 lock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
266 struct hrtimer_clock_base *base = timer->base;
268 raw_spin_lock_irqsave(&base->cpu_base->lock, *flags);
273 # define switch_hrtimer_base(t, b, p) (b)
275 #endif /* !CONFIG_SMP */
278 * Functions for the union type storage format of ktime_t which are
279 * too large for inlining:
281 #if BITS_PER_LONG < 64
283 * Divide a ktime value by a nanosecond value
285 s64 __ktime_divns(const ktime_t kt, s64 div)
291 dclc = ktime_to_ns(kt);
292 tmp = dclc < 0 ? -dclc : dclc;
294 /* Make sure the divisor is less than 2^32: */
300 do_div(tmp, (unsigned long) div);
301 return dclc < 0 ? -tmp : tmp;
303 EXPORT_SYMBOL_GPL(__ktime_divns);
304 #endif /* BITS_PER_LONG >= 64 */
307 * Add two ktime values and do a safety check for overflow:
309 ktime_t ktime_add_safe(const ktime_t lhs, const ktime_t rhs)
311 ktime_t res = ktime_add_unsafe(lhs, rhs);
314 * We use KTIME_SEC_MAX here, the maximum timeout which we can
315 * return to user space in a timespec:
317 if (res < 0 || res < lhs || res < rhs)
318 res = ktime_set(KTIME_SEC_MAX, 0);
323 EXPORT_SYMBOL_GPL(ktime_add_safe);
325 #ifdef CONFIG_DEBUG_OBJECTS_TIMERS
327 static struct debug_obj_descr hrtimer_debug_descr;
329 static void *hrtimer_debug_hint(void *addr)
331 return ((struct hrtimer *) addr)->function;
335 * fixup_init is called when:
336 * - an active object is initialized
338 static bool hrtimer_fixup_init(void *addr, enum debug_obj_state state)
340 struct hrtimer *timer = addr;
343 case ODEBUG_STATE_ACTIVE:
344 hrtimer_cancel(timer);
345 debug_object_init(timer, &hrtimer_debug_descr);
353 * fixup_activate is called when:
354 * - an active object is activated
355 * - an unknown non-static object is activated
357 static bool hrtimer_fixup_activate(void *addr, enum debug_obj_state state)
360 case ODEBUG_STATE_ACTIVE:
369 * fixup_free is called when:
370 * - an active object is freed
372 static bool hrtimer_fixup_free(void *addr, enum debug_obj_state state)
374 struct hrtimer *timer = addr;
377 case ODEBUG_STATE_ACTIVE:
378 hrtimer_cancel(timer);
379 debug_object_free(timer, &hrtimer_debug_descr);
386 static struct debug_obj_descr hrtimer_debug_descr = {
388 .debug_hint = hrtimer_debug_hint,
389 .fixup_init = hrtimer_fixup_init,
390 .fixup_activate = hrtimer_fixup_activate,
391 .fixup_free = hrtimer_fixup_free,
394 static inline void debug_hrtimer_init(struct hrtimer *timer)
396 debug_object_init(timer, &hrtimer_debug_descr);
399 static inline void debug_hrtimer_activate(struct hrtimer *timer)
401 debug_object_activate(timer, &hrtimer_debug_descr);
404 static inline void debug_hrtimer_deactivate(struct hrtimer *timer)
406 debug_object_deactivate(timer, &hrtimer_debug_descr);
409 static inline void debug_hrtimer_free(struct hrtimer *timer)
411 debug_object_free(timer, &hrtimer_debug_descr);
414 static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
415 enum hrtimer_mode mode);
417 void hrtimer_init_on_stack(struct hrtimer *timer, clockid_t clock_id,
418 enum hrtimer_mode mode)
420 debug_object_init_on_stack(timer, &hrtimer_debug_descr);
421 __hrtimer_init(timer, clock_id, mode);
423 EXPORT_SYMBOL_GPL(hrtimer_init_on_stack);
425 void destroy_hrtimer_on_stack(struct hrtimer *timer)
427 debug_object_free(timer, &hrtimer_debug_descr);
429 EXPORT_SYMBOL_GPL(destroy_hrtimer_on_stack);
432 static inline void debug_hrtimer_init(struct hrtimer *timer) { }
433 static inline void debug_hrtimer_activate(struct hrtimer *timer) { }
434 static inline void debug_hrtimer_deactivate(struct hrtimer *timer) { }
438 debug_init(struct hrtimer *timer, clockid_t clockid,
439 enum hrtimer_mode mode)
441 debug_hrtimer_init(timer);
442 trace_hrtimer_init(timer, clockid, mode);
445 static inline void debug_activate(struct hrtimer *timer)
447 debug_hrtimer_activate(timer);
448 trace_hrtimer_start(timer);
451 static inline void debug_deactivate(struct hrtimer *timer)
453 debug_hrtimer_deactivate(timer);
454 trace_hrtimer_cancel(timer);
457 #if defined(CONFIG_NO_HZ_COMMON) || defined(CONFIG_HIGH_RES_TIMERS)
458 static inline void hrtimer_update_next_timer(struct hrtimer_cpu_base *cpu_base,
459 struct hrtimer *timer)
461 #ifdef CONFIG_HIGH_RES_TIMERS
462 cpu_base->next_timer = timer;
466 static ktime_t __hrtimer_get_next_event(struct hrtimer_cpu_base *cpu_base)
468 struct hrtimer_clock_base *base = cpu_base->clock_base;
469 unsigned int active = cpu_base->active_bases;
470 ktime_t expires, expires_next = KTIME_MAX;
472 hrtimer_update_next_timer(cpu_base, NULL);
473 for (; active; base++, active >>= 1) {
474 struct timerqueue_node *next;
475 struct hrtimer *timer;
477 if (!(active & 0x01))
480 next = timerqueue_getnext(&base->active);
481 timer = container_of(next, struct hrtimer, node);
482 expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
483 if (expires < expires_next) {
484 expires_next = expires;
485 hrtimer_update_next_timer(cpu_base, timer);
489 * clock_was_set() might have changed base->offset of any of
490 * the clock bases so the result might be negative. Fix it up
491 * to prevent a false positive in clockevents_program_event().
493 if (expires_next < 0)
499 static inline ktime_t hrtimer_update_base(struct hrtimer_cpu_base *base)
501 ktime_t *offs_real = &base->clock_base[HRTIMER_BASE_REALTIME].offset;
502 ktime_t *offs_boot = &base->clock_base[HRTIMER_BASE_BOOTTIME].offset;
503 ktime_t *offs_tai = &base->clock_base[HRTIMER_BASE_TAI].offset;
505 return ktime_get_update_offsets_now(&base->clock_was_set_seq,
506 offs_real, offs_boot, offs_tai);
509 /* High resolution timer related functions */
510 #ifdef CONFIG_HIGH_RES_TIMERS
513 * High resolution timer enabled ?
515 static bool hrtimer_hres_enabled __read_mostly = true;
516 unsigned int hrtimer_resolution __read_mostly = LOW_RES_NSEC;
517 EXPORT_SYMBOL_GPL(hrtimer_resolution);
520 * Enable / Disable high resolution mode
522 static int __init setup_hrtimer_hres(char *str)
524 return (kstrtobool(str, &hrtimer_hres_enabled) == 0);
527 __setup("highres=", setup_hrtimer_hres);
530 * hrtimer_high_res_enabled - query, if the highres mode is enabled
532 static inline int hrtimer_is_hres_enabled(void)
534 return hrtimer_hres_enabled;
538 * Is the high resolution mode active ?
540 static inline int __hrtimer_hres_active(struct hrtimer_cpu_base *cpu_base)
542 return cpu_base->hres_active;
545 static inline int hrtimer_hres_active(void)
547 return __hrtimer_hres_active(this_cpu_ptr(&hrtimer_bases));
551 * Reprogram the event source with checking both queues for the
553 * Called with interrupts disabled and base->lock held
556 hrtimer_force_reprogram(struct hrtimer_cpu_base *cpu_base, int skip_equal)
558 ktime_t expires_next;
560 if (!cpu_base->hres_active)
563 expires_next = __hrtimer_get_next_event(cpu_base);
565 if (skip_equal && expires_next == cpu_base->expires_next)
568 cpu_base->expires_next = expires_next;
571 * If a hang was detected in the last timer interrupt then we
572 * leave the hang delay active in the hardware. We want the
573 * system to make progress. That also prevents the following
575 * T1 expires 50ms from now
576 * T2 expires 5s from now
578 * T1 is removed, so this code is called and would reprogram
579 * the hardware to 5s from now. Any hrtimer_start after that
580 * will not reprogram the hardware due to hang_detected being
581 * set. So we'd effectivly block all timers until the T2 event
584 if (cpu_base->hang_detected)
587 tick_program_event(cpu_base->expires_next, 1);
591 * When a timer is enqueued and expires earlier than the already enqueued
592 * timers, we have to check, whether it expires earlier than the timer for
593 * which the clock event device was armed.
595 * Called with interrupts disabled and base->cpu_base.lock held
597 static void hrtimer_reprogram(struct hrtimer *timer,
598 struct hrtimer_clock_base *base)
600 struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
601 ktime_t expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
603 WARN_ON_ONCE(hrtimer_get_expires_tv64(timer) < 0);
606 * If the timer is not on the current cpu, we cannot reprogram
607 * the other cpus clock event device.
609 if (base->cpu_base != cpu_base)
613 * If the hrtimer interrupt is running, then it will
614 * reevaluate the clock bases and reprogram the clock event
615 * device. The callbacks are always executed in hard interrupt
616 * context so we don't need an extra check for a running
619 if (cpu_base->in_hrtirq)
623 * CLOCK_REALTIME timer might be requested with an absolute
624 * expiry time which is less than base->offset. Set it to 0.
629 if (expires >= cpu_base->expires_next)
632 /* Update the pointer to the next expiring timer */
633 cpu_base->next_timer = timer;
636 * If a hang was detected in the last timer interrupt then we
637 * do not schedule a timer which is earlier than the expiry
638 * which we enforced in the hang detection. We want the system
641 if (cpu_base->hang_detected)
645 * Program the timer hardware. We enforce the expiry for
646 * events which are already in the past.
648 cpu_base->expires_next = expires;
649 tick_program_event(expires, 1);
653 * Initialize the high resolution related parts of cpu_base
655 static inline void hrtimer_init_hres(struct hrtimer_cpu_base *base)
657 base->expires_next = KTIME_MAX;
658 base->hang_detected = 0;
659 base->hres_active = 0;
660 base->next_timer = NULL;
664 * Retrigger next event is called after clock was set
666 * Called with interrupts disabled via on_each_cpu()
668 static void retrigger_next_event(void *arg)
670 struct hrtimer_cpu_base *base = this_cpu_ptr(&hrtimer_bases);
672 if (!base->hres_active)
675 raw_spin_lock(&base->lock);
676 hrtimer_update_base(base);
677 hrtimer_force_reprogram(base, 0);
678 raw_spin_unlock(&base->lock);
682 * Switch to high resolution mode
684 static void hrtimer_switch_to_hres(void)
686 struct hrtimer_cpu_base *base = this_cpu_ptr(&hrtimer_bases);
688 if (tick_init_highres()) {
689 printk(KERN_WARNING "Could not switch to high resolution "
690 "mode on CPU %d\n", base->cpu);
693 base->hres_active = 1;
694 hrtimer_resolution = HIGH_RES_NSEC;
696 tick_setup_sched_timer();
697 /* "Retrigger" the interrupt to get things going */
698 retrigger_next_event(NULL);
701 static void clock_was_set_work(struct work_struct *work)
706 static DECLARE_WORK(hrtimer_work, clock_was_set_work);
709 * Called from timekeeping and resume code to reprogram the hrtimer
710 * interrupt device on all cpus.
712 void clock_was_set_delayed(void)
714 schedule_work(&hrtimer_work);
719 static inline int __hrtimer_hres_active(struct hrtimer_cpu_base *b) { return 0; }
720 static inline int hrtimer_hres_active(void) { return 0; }
721 static inline int hrtimer_is_hres_enabled(void) { return 0; }
722 static inline void hrtimer_switch_to_hres(void) { }
724 hrtimer_force_reprogram(struct hrtimer_cpu_base *base, int skip_equal) { }
725 static inline int hrtimer_reprogram(struct hrtimer *timer,
726 struct hrtimer_clock_base *base)
730 static inline void hrtimer_init_hres(struct hrtimer_cpu_base *base) { }
731 static inline void retrigger_next_event(void *arg) { }
733 #endif /* CONFIG_HIGH_RES_TIMERS */
736 * Clock realtime was set
738 * Change the offset of the realtime clock vs. the monotonic
741 * We might have to reprogram the high resolution timer interrupt. On
742 * SMP we call the architecture specific code to retrigger _all_ high
743 * resolution timer interrupts. On UP we just disable interrupts and
744 * call the high resolution interrupt code.
746 void clock_was_set(void)
748 #ifdef CONFIG_HIGH_RES_TIMERS
749 /* Retrigger the CPU local events everywhere */
750 on_each_cpu(retrigger_next_event, NULL, 1);
752 timerfd_clock_was_set();
756 * During resume we might have to reprogram the high resolution timer
757 * interrupt on all online CPUs. However, all other CPUs will be
758 * stopped with IRQs interrupts disabled so the clock_was_set() call
761 void hrtimers_resume(void)
763 WARN_ONCE(!irqs_disabled(),
764 KERN_INFO "hrtimers_resume() called with IRQs enabled!");
766 /* Retrigger on the local CPU */
767 retrigger_next_event(NULL);
768 /* And schedule a retrigger for all others */
769 clock_was_set_delayed();
773 * Counterpart to lock_hrtimer_base above:
776 void unlock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
778 raw_spin_unlock_irqrestore(&timer->base->cpu_base->lock, *flags);
782 * hrtimer_forward - forward the timer expiry
783 * @timer: hrtimer to forward
784 * @now: forward past this time
785 * @interval: the interval to forward
787 * Forward the timer expiry so it will expire in the future.
788 * Returns the number of overruns.
790 * Can be safely called from the callback function of @timer. If
791 * called from other contexts @timer must neither be enqueued nor
792 * running the callback and the caller needs to take care of
795 * Note: This only updates the timer expiry value and does not requeue
798 u64 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval)
803 delta = ktime_sub(now, hrtimer_get_expires(timer));
808 if (WARN_ON(timer->state & HRTIMER_STATE_ENQUEUED))
811 if (interval < hrtimer_resolution)
812 interval = hrtimer_resolution;
814 if (unlikely(delta >= interval)) {
815 s64 incr = ktime_to_ns(interval);
817 orun = ktime_divns(delta, incr);
818 hrtimer_add_expires_ns(timer, incr * orun);
819 if (hrtimer_get_expires_tv64(timer) > now)
822 * This (and the ktime_add() below) is the
823 * correction for exact:
827 hrtimer_add_expires(timer, interval);
831 EXPORT_SYMBOL_GPL(hrtimer_forward);
834 * enqueue_hrtimer - internal function to (re)start a timer
836 * The timer is inserted in expiry order. Insertion into the
837 * red black tree is O(log(n)). Must hold the base lock.
839 * Returns 1 when the new timer is the leftmost timer in the tree.
841 static int enqueue_hrtimer(struct hrtimer *timer,
842 struct hrtimer_clock_base *base)
844 debug_activate(timer);
846 base->cpu_base->active_bases |= 1 << base->index;
848 /* Pairs with the lockless read in hrtimer_is_queued() */
849 WRITE_ONCE(timer->state, HRTIMER_STATE_ENQUEUED);
851 return timerqueue_add(&base->active, &timer->node);
855 * __remove_hrtimer - internal function to remove a timer
857 * Caller must hold the base lock.
859 * High resolution timer mode reprograms the clock event device when the
860 * timer is the one which expires next. The caller can disable this by setting
861 * reprogram to zero. This is useful, when the context does a reprogramming
862 * anyway (e.g. timer interrupt)
864 static void __remove_hrtimer(struct hrtimer *timer,
865 struct hrtimer_clock_base *base,
866 u8 newstate, int reprogram)
868 struct hrtimer_cpu_base *cpu_base = base->cpu_base;
869 u8 state = timer->state;
871 /* Pairs with the lockless read in hrtimer_is_queued() */
872 WRITE_ONCE(timer->state, newstate);
873 if (!(state & HRTIMER_STATE_ENQUEUED))
876 if (!timerqueue_del(&base->active, &timer->node))
877 cpu_base->active_bases &= ~(1 << base->index);
879 #ifdef CONFIG_HIGH_RES_TIMERS
881 * Note: If reprogram is false we do not update
882 * cpu_base->next_timer. This happens when we remove the first
883 * timer on a remote cpu. No harm as we never dereference
884 * cpu_base->next_timer. So the worst thing what can happen is
885 * an superflous call to hrtimer_force_reprogram() on the
886 * remote cpu later on if the same timer gets enqueued again.
888 if (reprogram && timer == cpu_base->next_timer)
889 hrtimer_force_reprogram(cpu_base, 1);
894 * remove hrtimer, called with base lock held
897 remove_hrtimer(struct hrtimer *timer, struct hrtimer_clock_base *base, bool restart)
899 u8 state = timer->state;
901 if (state & HRTIMER_STATE_ENQUEUED) {
905 * Remove the timer and force reprogramming when high
906 * resolution mode is active and the timer is on the current
907 * CPU. If we remove a timer on another CPU, reprogramming is
908 * skipped. The interrupt event on this CPU is fired and
909 * reprogramming happens in the interrupt handler. This is a
910 * rare case and less expensive than a smp call.
912 debug_deactivate(timer);
913 reprogram = base->cpu_base == this_cpu_ptr(&hrtimer_bases);
916 state = HRTIMER_STATE_INACTIVE;
918 __remove_hrtimer(timer, base, state, reprogram);
924 static inline ktime_t hrtimer_update_lowres(struct hrtimer *timer, ktime_t tim,
925 const enum hrtimer_mode mode)
927 #ifdef CONFIG_TIME_LOW_RES
929 * CONFIG_TIME_LOW_RES indicates that the system has no way to return
930 * granular time values. For relative timers we add hrtimer_resolution
931 * (i.e. one jiffie) to prevent short timeouts.
933 timer->is_rel = mode & HRTIMER_MODE_REL;
935 tim = ktime_add_safe(tim, hrtimer_resolution);
941 * hrtimer_start_range_ns - (re)start an hrtimer on the current CPU
942 * @timer: the timer to be added
944 * @delta_ns: "slack" range for the timer
945 * @mode: expiry mode: absolute (HRTIMER_MODE_ABS) or
946 * relative (HRTIMER_MODE_REL)
948 void hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
949 u64 delta_ns, const enum hrtimer_mode mode)
951 struct hrtimer_clock_base *base, *new_base;
955 base = lock_hrtimer_base(timer, &flags);
957 /* Remove an active timer from the queue: */
958 remove_hrtimer(timer, base, true);
960 if (mode & HRTIMER_MODE_REL)
961 tim = ktime_add_safe(tim, base->get_time());
963 tim = hrtimer_update_lowres(timer, tim, mode);
965 hrtimer_set_expires_range_ns(timer, tim, delta_ns);
967 /* Switch the timer base, if necessary: */
968 new_base = switch_hrtimer_base(timer, base, mode & HRTIMER_MODE_PINNED);
970 leftmost = enqueue_hrtimer(timer, new_base);
974 if (!hrtimer_is_hres_active(timer)) {
976 * Kick to reschedule the next tick to handle the new timer
977 * on dynticks target.
979 if (new_base->cpu_base->nohz_active)
980 wake_up_nohz_cpu(new_base->cpu_base->cpu);
982 hrtimer_reprogram(timer, new_base);
985 unlock_hrtimer_base(timer, &flags);
987 EXPORT_SYMBOL_GPL(hrtimer_start_range_ns);
990 * hrtimer_try_to_cancel - try to deactivate a timer
991 * @timer: hrtimer to stop
994 * 0 when the timer was not active
995 * 1 when the timer was active
996 * -1 when the timer is currently executing the callback function and
999 int hrtimer_try_to_cancel(struct hrtimer *timer)
1001 struct hrtimer_clock_base *base;
1002 unsigned long flags;
1006 * Check lockless first. If the timer is not active (neither
1007 * enqueued nor running the callback, nothing to do here. The
1008 * base lock does not serialize against a concurrent enqueue,
1009 * so we can avoid taking it.
1011 if (!hrtimer_active(timer))
1014 base = lock_hrtimer_base(timer, &flags);
1016 if (!hrtimer_callback_running(timer))
1017 ret = remove_hrtimer(timer, base, false);
1019 unlock_hrtimer_base(timer, &flags);
1024 EXPORT_SYMBOL_GPL(hrtimer_try_to_cancel);
1027 * hrtimer_cancel - cancel a timer and wait for the handler to finish.
1028 * @timer: the timer to be cancelled
1031 * 0 when the timer was not active
1032 * 1 when the timer was active
1034 int hrtimer_cancel(struct hrtimer *timer)
1037 int ret = hrtimer_try_to_cancel(timer);
1044 EXPORT_SYMBOL_GPL(hrtimer_cancel);
1047 * hrtimer_get_remaining - get remaining time for the timer
1048 * @timer: the timer to read
1049 * @adjust: adjust relative timers when CONFIG_TIME_LOW_RES=y
1051 ktime_t __hrtimer_get_remaining(const struct hrtimer *timer, bool adjust)
1053 unsigned long flags;
1056 lock_hrtimer_base(timer, &flags);
1057 if (IS_ENABLED(CONFIG_TIME_LOW_RES) && adjust)
1058 rem = hrtimer_expires_remaining_adjusted(timer);
1060 rem = hrtimer_expires_remaining(timer);
1061 unlock_hrtimer_base(timer, &flags);
1065 EXPORT_SYMBOL_GPL(__hrtimer_get_remaining);
1067 #ifdef CONFIG_NO_HZ_COMMON
1069 * hrtimer_get_next_event - get the time until next expiry event
1071 * Returns the next expiry time or KTIME_MAX if no timer is pending.
1073 u64 hrtimer_get_next_event(void)
1075 struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1076 u64 expires = KTIME_MAX;
1077 unsigned long flags;
1079 raw_spin_lock_irqsave(&cpu_base->lock, flags);
1081 if (!__hrtimer_hres_active(cpu_base))
1082 expires = __hrtimer_get_next_event(cpu_base);
1084 raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1090 static inline int hrtimer_clockid_to_base(clockid_t clock_id)
1092 if (likely(clock_id < MAX_CLOCKS)) {
1093 int base = hrtimer_clock_to_base_table[clock_id];
1095 if (likely(base != HRTIMER_MAX_CLOCK_BASES))
1098 WARN(1, "Invalid clockid %d. Using MONOTONIC\n", clock_id);
1099 return HRTIMER_BASE_MONOTONIC;
1102 static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
1103 enum hrtimer_mode mode)
1105 struct hrtimer_cpu_base *cpu_base;
1108 memset(timer, 0, sizeof(struct hrtimer));
1110 cpu_base = raw_cpu_ptr(&hrtimer_bases);
1113 * POSIX magic: Relative CLOCK_REALTIME timers are not affected by
1114 * clock modifications, so they needs to become CLOCK_MONOTONIC to
1115 * ensure POSIX compliance.
1117 if (clock_id == CLOCK_REALTIME && mode & HRTIMER_MODE_REL)
1118 clock_id = CLOCK_MONOTONIC;
1120 base = hrtimer_clockid_to_base(clock_id);
1121 timer->base = &cpu_base->clock_base[base];
1122 timerqueue_init(&timer->node);
1126 * hrtimer_init - initialize a timer to the given clock
1127 * @timer: the timer to be initialized
1128 * @clock_id: the clock to be used
1129 * @mode: timer mode abs/rel
1131 void hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
1132 enum hrtimer_mode mode)
1134 debug_init(timer, clock_id, mode);
1135 __hrtimer_init(timer, clock_id, mode);
1137 EXPORT_SYMBOL_GPL(hrtimer_init);
1140 * A timer is active, when it is enqueued into the rbtree or the
1141 * callback function is running or it's in the state of being migrated
1144 * It is important for this function to not return a false negative.
1146 bool hrtimer_active(const struct hrtimer *timer)
1148 struct hrtimer_cpu_base *cpu_base;
1152 cpu_base = READ_ONCE(timer->base->cpu_base);
1153 seq = raw_read_seqcount_begin(&cpu_base->seq);
1155 if (timer->state != HRTIMER_STATE_INACTIVE ||
1156 cpu_base->running == timer)
1159 } while (read_seqcount_retry(&cpu_base->seq, seq) ||
1160 cpu_base != READ_ONCE(timer->base->cpu_base));
1164 EXPORT_SYMBOL_GPL(hrtimer_active);
1167 * The write_seqcount_barrier()s in __run_hrtimer() split the thing into 3
1168 * distinct sections:
1170 * - queued: the timer is queued
1171 * - callback: the timer is being ran
1172 * - post: the timer is inactive or (re)queued
1174 * On the read side we ensure we observe timer->state and cpu_base->running
1175 * from the same section, if anything changed while we looked at it, we retry.
1176 * This includes timer->base changing because sequence numbers alone are
1177 * insufficient for that.
1179 * The sequence numbers are required because otherwise we could still observe
1180 * a false negative if the read side got smeared over multiple consequtive
1181 * __run_hrtimer() invocations.
1184 static void __run_hrtimer(struct hrtimer_cpu_base *cpu_base,
1185 struct hrtimer_clock_base *base,
1186 struct hrtimer *timer, ktime_t *now)
1188 enum hrtimer_restart (*fn)(struct hrtimer *);
1191 lockdep_assert_held(&cpu_base->lock);
1193 debug_deactivate(timer);
1194 cpu_base->running = timer;
1197 * Separate the ->running assignment from the ->state assignment.
1199 * As with a regular write barrier, this ensures the read side in
1200 * hrtimer_active() cannot observe cpu_base->running == NULL &&
1201 * timer->state == INACTIVE.
1203 raw_write_seqcount_barrier(&cpu_base->seq);
1205 __remove_hrtimer(timer, base, HRTIMER_STATE_INACTIVE, 0);
1206 fn = timer->function;
1209 * Clear the 'is relative' flag for the TIME_LOW_RES case. If the
1210 * timer is restarted with a period then it becomes an absolute
1211 * timer. If its not restarted it does not matter.
1213 if (IS_ENABLED(CONFIG_TIME_LOW_RES))
1214 timer->is_rel = false;
1217 * Because we run timers from hardirq context, there is no chance
1218 * they get migrated to another cpu, therefore its safe to unlock
1221 raw_spin_unlock(&cpu_base->lock);
1222 trace_hrtimer_expire_entry(timer, now);
1223 restart = fn(timer);
1224 trace_hrtimer_expire_exit(timer);
1225 raw_spin_lock(&cpu_base->lock);
1228 * Note: We clear the running state after enqueue_hrtimer and
1229 * we do not reprogram the event hardware. Happens either in
1230 * hrtimer_start_range_ns() or in hrtimer_interrupt()
1232 * Note: Because we dropped the cpu_base->lock above,
1233 * hrtimer_start_range_ns() can have popped in and enqueued the timer
1236 if (restart != HRTIMER_NORESTART &&
1237 !(timer->state & HRTIMER_STATE_ENQUEUED))
1238 enqueue_hrtimer(timer, base);
1241 * Separate the ->running assignment from the ->state assignment.
1243 * As with a regular write barrier, this ensures the read side in
1244 * hrtimer_active() cannot observe cpu_base->running == NULL &&
1245 * timer->state == INACTIVE.
1247 raw_write_seqcount_barrier(&cpu_base->seq);
1249 WARN_ON_ONCE(cpu_base->running != timer);
1250 cpu_base->running = NULL;
1253 static void __hrtimer_run_queues(struct hrtimer_cpu_base *cpu_base, ktime_t now)
1255 struct hrtimer_clock_base *base = cpu_base->clock_base;
1256 unsigned int active = cpu_base->active_bases;
1258 for (; active; base++, active >>= 1) {
1259 struct timerqueue_node *node;
1262 if (!(active & 0x01))
1265 basenow = ktime_add(now, base->offset);
1267 while ((node = timerqueue_getnext(&base->active))) {
1268 struct hrtimer *timer;
1270 timer = container_of(node, struct hrtimer, node);
1273 * The immediate goal for using the softexpires is
1274 * minimizing wakeups, not running timers at the
1275 * earliest interrupt after their soft expiration.
1276 * This allows us to avoid using a Priority Search
1277 * Tree, which can answer a stabbing querry for
1278 * overlapping intervals and instead use the simple
1279 * BST we already have.
1280 * We don't add extra wakeups by delaying timers that
1281 * are right-of a not yet expired timer, because that
1282 * timer will have to trigger a wakeup anyway.
1284 if (basenow < hrtimer_get_softexpires_tv64(timer))
1287 __run_hrtimer(cpu_base, base, timer, &basenow);
1292 #ifdef CONFIG_HIGH_RES_TIMERS
1295 * High resolution timer interrupt
1296 * Called with interrupts disabled
1298 void hrtimer_interrupt(struct clock_event_device *dev)
1300 struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1301 ktime_t expires_next, now, entry_time, delta;
1304 BUG_ON(!cpu_base->hres_active);
1305 cpu_base->nr_events++;
1306 dev->next_event = KTIME_MAX;
1308 raw_spin_lock(&cpu_base->lock);
1309 entry_time = now = hrtimer_update_base(cpu_base);
1311 cpu_base->in_hrtirq = 1;
1313 * We set expires_next to KTIME_MAX here with cpu_base->lock
1314 * held to prevent that a timer is enqueued in our queue via
1315 * the migration code. This does not affect enqueueing of
1316 * timers which run their callback and need to be requeued on
1319 cpu_base->expires_next = KTIME_MAX;
1321 __hrtimer_run_queues(cpu_base, now);
1323 /* Reevaluate the clock bases for the next expiry */
1324 expires_next = __hrtimer_get_next_event(cpu_base);
1326 * Store the new expiry value so the migration code can verify
1329 cpu_base->expires_next = expires_next;
1330 cpu_base->in_hrtirq = 0;
1331 raw_spin_unlock(&cpu_base->lock);
1333 /* Reprogramming necessary ? */
1334 if (!tick_program_event(expires_next, 0)) {
1335 cpu_base->hang_detected = 0;
1340 * The next timer was already expired due to:
1342 * - long lasting callbacks
1343 * - being scheduled away when running in a VM
1345 * We need to prevent that we loop forever in the hrtimer
1346 * interrupt routine. We give it 3 attempts to avoid
1347 * overreacting on some spurious event.
1349 * Acquire base lock for updating the offsets and retrieving
1352 raw_spin_lock(&cpu_base->lock);
1353 now = hrtimer_update_base(cpu_base);
1354 cpu_base->nr_retries++;
1358 * Give the system a chance to do something else than looping
1359 * here. We stored the entry time, so we know exactly how long
1360 * we spent here. We schedule the next event this amount of
1363 cpu_base->nr_hangs++;
1364 cpu_base->hang_detected = 1;
1365 raw_spin_unlock(&cpu_base->lock);
1366 delta = ktime_sub(now, entry_time);
1367 if ((unsigned int)delta > cpu_base->max_hang_time)
1368 cpu_base->max_hang_time = (unsigned int) delta;
1370 * Limit it to a sensible value as we enforce a longer
1371 * delay. Give the CPU at least 100ms to catch up.
1373 if (delta > 100 * NSEC_PER_MSEC)
1374 expires_next = ktime_add_ns(now, 100 * NSEC_PER_MSEC);
1376 expires_next = ktime_add(now, delta);
1377 tick_program_event(expires_next, 1);
1378 printk_once(KERN_WARNING "hrtimer: interrupt took %llu ns\n",
1379 ktime_to_ns(delta));
1382 /* called with interrupts disabled */
1383 static inline void __hrtimer_peek_ahead_timers(void)
1385 struct tick_device *td;
1387 if (!hrtimer_hres_active())
1390 td = this_cpu_ptr(&tick_cpu_device);
1391 if (td && td->evtdev)
1392 hrtimer_interrupt(td->evtdev);
1395 #else /* CONFIG_HIGH_RES_TIMERS */
1397 static inline void __hrtimer_peek_ahead_timers(void) { }
1399 #endif /* !CONFIG_HIGH_RES_TIMERS */
1402 * Called from run_local_timers in hardirq context every jiffy
1404 void hrtimer_run_queues(void)
1406 struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1409 if (__hrtimer_hres_active(cpu_base))
1413 * This _is_ ugly: We have to check periodically, whether we
1414 * can switch to highres and / or nohz mode. The clocksource
1415 * switch happens with xtime_lock held. Notification from
1416 * there only sets the check bit in the tick_oneshot code,
1417 * otherwise we might deadlock vs. xtime_lock.
1419 if (tick_check_oneshot_change(!hrtimer_is_hres_enabled())) {
1420 hrtimer_switch_to_hres();
1424 raw_spin_lock(&cpu_base->lock);
1425 now = hrtimer_update_base(cpu_base);
1426 __hrtimer_run_queues(cpu_base, now);
1427 raw_spin_unlock(&cpu_base->lock);
1431 * Sleep related functions:
1433 static enum hrtimer_restart hrtimer_wakeup(struct hrtimer *timer)
1435 struct hrtimer_sleeper *t =
1436 container_of(timer, struct hrtimer_sleeper, timer);
1437 struct task_struct *task = t->task;
1441 wake_up_process(task);
1443 return HRTIMER_NORESTART;
1446 void hrtimer_init_sleeper(struct hrtimer_sleeper *sl, struct task_struct *task)
1448 sl->timer.function = hrtimer_wakeup;
1451 EXPORT_SYMBOL_GPL(hrtimer_init_sleeper);
1453 int nanosleep_copyout(struct restart_block *restart, struct timespec64 *ts)
1455 switch(restart->nanosleep.type) {
1456 #ifdef CONFIG_COMPAT
1458 if (compat_put_timespec64(ts, restart->nanosleep.compat_rmtp))
1463 if (put_timespec64(ts, restart->nanosleep.rmtp))
1469 return -ERESTART_RESTARTBLOCK;
1472 static int __sched do_nanosleep(struct hrtimer_sleeper *t, enum hrtimer_mode mode)
1474 struct restart_block *restart;
1476 hrtimer_init_sleeper(t, current);
1479 set_current_state(TASK_INTERRUPTIBLE);
1480 hrtimer_start_expires(&t->timer, mode);
1482 if (likely(t->task))
1483 freezable_schedule();
1485 hrtimer_cancel(&t->timer);
1486 mode = HRTIMER_MODE_ABS;
1488 } while (t->task && !signal_pending(current));
1490 __set_current_state(TASK_RUNNING);
1495 restart = ¤t->restart_block;
1496 if (restart->nanosleep.type != TT_NONE) {
1497 ktime_t rem = hrtimer_expires_remaining(&t->timer);
1498 struct timespec64 rmt;
1502 rmt = ktime_to_timespec64(rem);
1504 return nanosleep_copyout(restart, &rmt);
1506 return -ERESTART_RESTARTBLOCK;
1509 static long __sched hrtimer_nanosleep_restart(struct restart_block *restart)
1511 struct hrtimer_sleeper t;
1514 hrtimer_init_on_stack(&t.timer, restart->nanosleep.clockid,
1516 hrtimer_set_expires_tv64(&t.timer, restart->nanosleep.expires);
1518 ret = do_nanosleep(&t, HRTIMER_MODE_ABS);
1519 destroy_hrtimer_on_stack(&t.timer);
1523 long hrtimer_nanosleep(const struct timespec64 *rqtp,
1524 const enum hrtimer_mode mode, const clockid_t clockid)
1526 struct restart_block *restart;
1527 struct hrtimer_sleeper t;
1531 slack = current->timer_slack_ns;
1532 if (dl_task(current) || rt_task(current))
1535 hrtimer_init_on_stack(&t.timer, clockid, mode);
1536 hrtimer_set_expires_range_ns(&t.timer, timespec64_to_ktime(*rqtp), slack);
1537 ret = do_nanosleep(&t, mode);
1538 if (ret != -ERESTART_RESTARTBLOCK)
1541 /* Absolute timers do not update the rmtp value and restart: */
1542 if (mode == HRTIMER_MODE_ABS) {
1543 ret = -ERESTARTNOHAND;
1547 restart = ¤t->restart_block;
1548 restart->nanosleep.clockid = t.timer.base->clockid;
1549 restart->nanosleep.expires = hrtimer_get_expires_tv64(&t.timer);
1550 set_restart_fn(restart, hrtimer_nanosleep_restart);
1552 destroy_hrtimer_on_stack(&t.timer);
1556 SYSCALL_DEFINE2(nanosleep, struct timespec __user *, rqtp,
1557 struct timespec __user *, rmtp)
1559 struct timespec64 tu;
1561 if (get_timespec64(&tu, rqtp))
1564 if (!timespec64_valid(&tu))
1567 current->restart_block.fn = do_no_restart_syscall;
1568 current->restart_block.nanosleep.type = rmtp ? TT_NATIVE : TT_NONE;
1569 current->restart_block.nanosleep.rmtp = rmtp;
1570 return hrtimer_nanosleep(&tu, HRTIMER_MODE_REL, CLOCK_MONOTONIC);
1573 #ifdef CONFIG_COMPAT
1575 COMPAT_SYSCALL_DEFINE2(nanosleep, struct compat_timespec __user *, rqtp,
1576 struct compat_timespec __user *, rmtp)
1578 struct timespec64 tu;
1580 if (compat_get_timespec64(&tu, rqtp))
1583 if (!timespec64_valid(&tu))
1586 current->restart_block.fn = do_no_restart_syscall;
1587 current->restart_block.nanosleep.type = rmtp ? TT_COMPAT : TT_NONE;
1588 current->restart_block.nanosleep.compat_rmtp = rmtp;
1589 return hrtimer_nanosleep(&tu, HRTIMER_MODE_REL, CLOCK_MONOTONIC);
1594 * Functions related to boot-time initialization:
1596 int hrtimers_prepare_cpu(unsigned int cpu)
1598 struct hrtimer_cpu_base *cpu_base = &per_cpu(hrtimer_bases, cpu);
1601 for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
1602 cpu_base->clock_base[i].cpu_base = cpu_base;
1603 timerqueue_init_head(&cpu_base->clock_base[i].active);
1606 cpu_base->active_bases = 0;
1607 cpu_base->cpu = cpu;
1608 hrtimer_init_hres(cpu_base);
1612 #ifdef CONFIG_HOTPLUG_CPU
1614 static void migrate_hrtimer_list(struct hrtimer_clock_base *old_base,
1615 struct hrtimer_clock_base *new_base)
1617 struct hrtimer *timer;
1618 struct timerqueue_node *node;
1620 while ((node = timerqueue_getnext(&old_base->active))) {
1621 timer = container_of(node, struct hrtimer, node);
1622 BUG_ON(hrtimer_callback_running(timer));
1623 debug_deactivate(timer);
1626 * Mark it as ENQUEUED not INACTIVE otherwise the
1627 * timer could be seen as !active and just vanish away
1628 * under us on another CPU
1630 __remove_hrtimer(timer, old_base, HRTIMER_STATE_ENQUEUED, 0);
1631 timer->base = new_base;
1633 * Enqueue the timers on the new cpu. This does not
1634 * reprogram the event device in case the timer
1635 * expires before the earliest on this CPU, but we run
1636 * hrtimer_interrupt after we migrated everything to
1637 * sort out already expired timers and reprogram the
1640 enqueue_hrtimer(timer, new_base);
1644 int hrtimers_dead_cpu(unsigned int scpu)
1646 struct hrtimer_cpu_base *old_base, *new_base;
1649 BUG_ON(cpu_online(scpu));
1650 tick_cancel_sched_timer(scpu);
1652 local_irq_disable();
1653 old_base = &per_cpu(hrtimer_bases, scpu);
1654 new_base = this_cpu_ptr(&hrtimer_bases);
1656 * The caller is globally serialized and nobody else
1657 * takes two locks at once, deadlock is not possible.
1659 raw_spin_lock(&new_base->lock);
1660 raw_spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING);
1662 for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
1663 migrate_hrtimer_list(&old_base->clock_base[i],
1664 &new_base->clock_base[i]);
1667 raw_spin_unlock(&old_base->lock);
1668 raw_spin_unlock(&new_base->lock);
1670 /* Check, if we got expired work to do */
1671 __hrtimer_peek_ahead_timers();
1676 #endif /* CONFIG_HOTPLUG_CPU */
1678 void __init hrtimers_init(void)
1680 hrtimers_prepare_cpu(smp_processor_id());
1684 * schedule_hrtimeout_range_clock - sleep until timeout
1685 * @expires: timeout value (ktime_t)
1686 * @delta: slack in expires timeout (ktime_t)
1687 * @mode: timer mode, HRTIMER_MODE_ABS or HRTIMER_MODE_REL
1688 * @clock: timer clock, CLOCK_MONOTONIC or CLOCK_REALTIME
1691 schedule_hrtimeout_range_clock(ktime_t *expires, u64 delta,
1692 const enum hrtimer_mode mode, int clock)
1694 struct hrtimer_sleeper t;
1697 * Optimize when a zero timeout value is given. It does not
1698 * matter whether this is an absolute or a relative time.
1700 if (expires && *expires == 0) {
1701 __set_current_state(TASK_RUNNING);
1706 * A NULL parameter means "infinite"
1713 hrtimer_init_on_stack(&t.timer, clock, mode);
1714 hrtimer_set_expires_range_ns(&t.timer, *expires, delta);
1716 hrtimer_init_sleeper(&t, current);
1718 hrtimer_start_expires(&t.timer, mode);
1723 hrtimer_cancel(&t.timer);
1724 destroy_hrtimer_on_stack(&t.timer);
1726 __set_current_state(TASK_RUNNING);
1728 return !t.task ? 0 : -EINTR;
1732 * schedule_hrtimeout_range - sleep until timeout
1733 * @expires: timeout value (ktime_t)
1734 * @delta: slack in expires timeout (ktime_t)
1735 * @mode: timer mode, HRTIMER_MODE_ABS or HRTIMER_MODE_REL
1737 * Make the current task sleep until the given expiry time has
1738 * elapsed. The routine will return immediately unless
1739 * the current task state has been set (see set_current_state()).
1741 * The @delta argument gives the kernel the freedom to schedule the
1742 * actual wakeup to a time that is both power and performance friendly.
1743 * The kernel give the normal best effort behavior for "@expires+@delta",
1744 * but may decide to fire the timer earlier, but no earlier than @expires.
1746 * You can set the task state as follows -
1748 * %TASK_UNINTERRUPTIBLE - at least @timeout time is guaranteed to
1749 * pass before the routine returns unless the current task is explicitly
1750 * woken up, (e.g. by wake_up_process()).
1752 * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
1753 * delivered to the current task or the current task is explicitly woken
1756 * The current task state is guaranteed to be TASK_RUNNING when this
1759 * Returns 0 when the timer has expired. If the task was woken before the
1760 * timer expired by a signal (only possible in state TASK_INTERRUPTIBLE) or
1761 * by an explicit wakeup, it returns -EINTR.
1763 int __sched schedule_hrtimeout_range(ktime_t *expires, u64 delta,
1764 const enum hrtimer_mode mode)
1766 return schedule_hrtimeout_range_clock(expires, delta, mode,
1769 EXPORT_SYMBOL_GPL(schedule_hrtimeout_range);
1772 * schedule_hrtimeout - sleep until timeout
1773 * @expires: timeout value (ktime_t)
1774 * @mode: timer mode, HRTIMER_MODE_ABS or HRTIMER_MODE_REL
1776 * Make the current task sleep until the given expiry time has
1777 * elapsed. The routine will return immediately unless
1778 * the current task state has been set (see set_current_state()).
1780 * You can set the task state as follows -
1782 * %TASK_UNINTERRUPTIBLE - at least @timeout time is guaranteed to
1783 * pass before the routine returns unless the current task is explicitly
1784 * woken up, (e.g. by wake_up_process()).
1786 * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
1787 * delivered to the current task or the current task is explicitly woken
1790 * The current task state is guaranteed to be TASK_RUNNING when this
1793 * Returns 0 when the timer has expired. If the task was woken before the
1794 * timer expired by a signal (only possible in state TASK_INTERRUPTIBLE) or
1795 * by an explicit wakeup, it returns -EINTR.
1797 int __sched schedule_hrtimeout(ktime_t *expires,
1798 const enum hrtimer_mode mode)
1800 return schedule_hrtimeout_range(expires, 0, mode);
1802 EXPORT_SYMBOL_GPL(schedule_hrtimeout);