1 // SPDX-License-Identifier: GPL-2.0
4 * Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
5 * Copyright(C) 2006-2007 Timesys Corp., Thomas Gleixner
7 * High-resolution kernel timers
9 * In contrast to the low-resolution timeout API, aka timer wheel,
10 * hrtimers provide finer resolution and accuracy depending on system
11 * configuration and capabilities.
13 * Started by: Thomas Gleixner and Ingo Molnar
16 * Based on the original timer wheel code
18 * Help, testing, suggestions, bugfixes, improvements were
21 * George Anzinger, Andrew Morton, Steven Rostedt, Roman Zippel
25 #include <linux/cpu.h>
26 #include <linux/export.h>
27 #include <linux/percpu.h>
28 #include <linux/hrtimer.h>
29 #include <linux/notifier.h>
30 #include <linux/syscalls.h>
31 #include <linux/interrupt.h>
32 #include <linux/tick.h>
33 #include <linux/err.h>
34 #include <linux/debugobjects.h>
35 #include <linux/sched/signal.h>
36 #include <linux/sched/sysctl.h>
37 #include <linux/sched/rt.h>
38 #include <linux/sched/deadline.h>
39 #include <linux/sched/nohz.h>
40 #include <linux/sched/debug.h>
41 #include <linux/sched/isolation.h>
42 #include <linux/timer.h>
43 #include <linux/freezer.h>
44 #include <linux/compat.h>
46 #include <linux/uaccess.h>
48 #include <trace/events/timer.h>
50 #include "tick-internal.h"
53 * Masks for selecting the soft and hard context timers from
56 #define MASK_SHIFT (HRTIMER_BASE_MONOTONIC_SOFT)
57 #define HRTIMER_ACTIVE_HARD ((1U << MASK_SHIFT) - 1)
58 #define HRTIMER_ACTIVE_SOFT (HRTIMER_ACTIVE_HARD << MASK_SHIFT)
59 #define HRTIMER_ACTIVE_ALL (HRTIMER_ACTIVE_SOFT | HRTIMER_ACTIVE_HARD)
64 * There are more clockids than hrtimer bases. Thus, we index
65 * into the timer bases by the hrtimer_base_type enum. When trying
66 * to reach a base using a clockid, hrtimer_clockid_to_base()
67 * is used to convert from clockid to the proper hrtimer_base_type.
69 DEFINE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases) =
71 .lock = __RAW_SPIN_LOCK_UNLOCKED(hrtimer_bases.lock),
75 .index = HRTIMER_BASE_MONOTONIC,
76 .clockid = CLOCK_MONOTONIC,
77 .get_time = &ktime_get,
80 .index = HRTIMER_BASE_REALTIME,
81 .clockid = CLOCK_REALTIME,
82 .get_time = &ktime_get_real,
85 .index = HRTIMER_BASE_BOOTTIME,
86 .clockid = CLOCK_BOOTTIME,
87 .get_time = &ktime_get_boottime,
90 .index = HRTIMER_BASE_TAI,
92 .get_time = &ktime_get_clocktai,
95 .index = HRTIMER_BASE_MONOTONIC_SOFT,
96 .clockid = CLOCK_MONOTONIC,
97 .get_time = &ktime_get,
100 .index = HRTIMER_BASE_REALTIME_SOFT,
101 .clockid = CLOCK_REALTIME,
102 .get_time = &ktime_get_real,
105 .index = HRTIMER_BASE_BOOTTIME_SOFT,
106 .clockid = CLOCK_BOOTTIME,
107 .get_time = &ktime_get_boottime,
110 .index = HRTIMER_BASE_TAI_SOFT,
111 .clockid = CLOCK_TAI,
112 .get_time = &ktime_get_clocktai,
117 static const int hrtimer_clock_to_base_table[MAX_CLOCKS] = {
118 /* Make sure we catch unsupported clockids */
119 [0 ... MAX_CLOCKS - 1] = HRTIMER_MAX_CLOCK_BASES,
121 [CLOCK_REALTIME] = HRTIMER_BASE_REALTIME,
122 [CLOCK_MONOTONIC] = HRTIMER_BASE_MONOTONIC,
123 [CLOCK_BOOTTIME] = HRTIMER_BASE_BOOTTIME,
124 [CLOCK_TAI] = HRTIMER_BASE_TAI,
128 * Functions and macros which are different for UP/SMP systems are kept in a
134 * We require the migration_base for lock_hrtimer_base()/switch_hrtimer_base()
135 * such that hrtimer_callback_running() can unconditionally dereference
136 * timer->base->cpu_base
138 static struct hrtimer_cpu_base migration_cpu_base = {
140 .cpu_base = &migration_cpu_base,
141 .seq = SEQCNT_RAW_SPINLOCK_ZERO(migration_cpu_base.seq,
142 &migration_cpu_base.lock),
146 #define migration_base migration_cpu_base.clock_base[0]
148 static inline bool is_migration_base(struct hrtimer_clock_base *base)
150 return base == &migration_base;
154 * We are using hashed locking: holding per_cpu(hrtimer_bases)[n].lock
155 * means that all timers which are tied to this base via timer->base are
156 * locked, and the base itself is locked too.
158 * So __run_timers/migrate_timers can safely modify all timers which could
159 * be found on the lists/queues.
161 * When the timer's base is locked, and the timer removed from list, it is
162 * possible to set timer->base = &migration_base and drop the lock: the timer
166 struct hrtimer_clock_base *lock_hrtimer_base(const struct hrtimer *timer,
167 unsigned long *flags)
168 __acquires(&timer->base->lock)
170 struct hrtimer_clock_base *base;
173 base = READ_ONCE(timer->base);
174 if (likely(base != &migration_base)) {
175 raw_spin_lock_irqsave(&base->cpu_base->lock, *flags);
176 if (likely(base == timer->base))
178 /* The timer has migrated to another CPU: */
179 raw_spin_unlock_irqrestore(&base->cpu_base->lock, *flags);
186 * We do not migrate the timer when it is expiring before the next
187 * event on the target cpu. When high resolution is enabled, we cannot
188 * reprogram the target cpu hardware and we would cause it to fire
189 * late. To keep it simple, we handle the high resolution enabled and
190 * disabled case similar.
192 * Called with cpu_base->lock of target cpu held.
195 hrtimer_check_target(struct hrtimer *timer, struct hrtimer_clock_base *new_base)
199 expires = ktime_sub(hrtimer_get_expires(timer), new_base->offset);
200 return expires < new_base->cpu_base->expires_next;
204 struct hrtimer_cpu_base *get_target_base(struct hrtimer_cpu_base *base,
207 #if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ_COMMON)
208 if (static_branch_likely(&timers_migration_enabled) && !pinned)
209 return &per_cpu(hrtimer_bases, get_nohz_timer_target());
215 * We switch the timer base to a power-optimized selected CPU target,
217 * - NO_HZ_COMMON is enabled
218 * - timer migration is enabled
219 * - the timer callback is not running
220 * - the timer is not the first expiring timer on the new target
222 * If one of the above requirements is not fulfilled we move the timer
223 * to the current CPU or leave it on the previously assigned CPU if
224 * the timer callback is currently running.
226 static inline struct hrtimer_clock_base *
227 switch_hrtimer_base(struct hrtimer *timer, struct hrtimer_clock_base *base,
230 struct hrtimer_cpu_base *new_cpu_base, *this_cpu_base;
231 struct hrtimer_clock_base *new_base;
232 int basenum = base->index;
234 this_cpu_base = this_cpu_ptr(&hrtimer_bases);
235 new_cpu_base = get_target_base(this_cpu_base, pinned);
237 new_base = &new_cpu_base->clock_base[basenum];
239 if (base != new_base) {
241 * We are trying to move timer to new_base.
242 * However we can't change timer's base while it is running,
243 * so we keep it on the same CPU. No hassle vs. reprogramming
244 * the event source in the high resolution case. The softirq
245 * code will take care of this when the timer function has
246 * completed. There is no conflict as we hold the lock until
247 * the timer is enqueued.
249 if (unlikely(hrtimer_callback_running(timer)))
252 /* See the comment in lock_hrtimer_base() */
253 WRITE_ONCE(timer->base, &migration_base);
254 raw_spin_unlock(&base->cpu_base->lock);
255 raw_spin_lock(&new_base->cpu_base->lock);
257 if (new_cpu_base != this_cpu_base &&
258 hrtimer_check_target(timer, new_base)) {
259 raw_spin_unlock(&new_base->cpu_base->lock);
260 raw_spin_lock(&base->cpu_base->lock);
261 new_cpu_base = this_cpu_base;
262 WRITE_ONCE(timer->base, base);
265 WRITE_ONCE(timer->base, new_base);
267 if (new_cpu_base != this_cpu_base &&
268 hrtimer_check_target(timer, new_base)) {
269 new_cpu_base = this_cpu_base;
276 #else /* CONFIG_SMP */
278 static inline bool is_migration_base(struct hrtimer_clock_base *base)
283 static inline struct hrtimer_clock_base *
284 lock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
285 __acquires(&timer->base->cpu_base->lock)
287 struct hrtimer_clock_base *base = timer->base;
289 raw_spin_lock_irqsave(&base->cpu_base->lock, *flags);
294 # define switch_hrtimer_base(t, b, p) (b)
296 #endif /* !CONFIG_SMP */
299 * Functions for the union type storage format of ktime_t which are
300 * too large for inlining:
302 #if BITS_PER_LONG < 64
304 * Divide a ktime value by a nanosecond value
306 s64 __ktime_divns(const ktime_t kt, s64 div)
312 dclc = ktime_to_ns(kt);
313 tmp = dclc < 0 ? -dclc : dclc;
315 /* Make sure the divisor is less than 2^32: */
321 do_div(tmp, (u32) div);
322 return dclc < 0 ? -tmp : tmp;
324 EXPORT_SYMBOL_GPL(__ktime_divns);
325 #endif /* BITS_PER_LONG >= 64 */
328 * Add two ktime values and do a safety check for overflow:
330 ktime_t ktime_add_safe(const ktime_t lhs, const ktime_t rhs)
332 ktime_t res = ktime_add_unsafe(lhs, rhs);
335 * We use KTIME_SEC_MAX here, the maximum timeout which we can
336 * return to user space in a timespec:
338 if (res < 0 || res < lhs || res < rhs)
339 res = ktime_set(KTIME_SEC_MAX, 0);
344 EXPORT_SYMBOL_GPL(ktime_add_safe);
346 #ifdef CONFIG_DEBUG_OBJECTS_TIMERS
348 static const struct debug_obj_descr hrtimer_debug_descr;
350 static void *hrtimer_debug_hint(void *addr)
352 return ((struct hrtimer *) addr)->function;
356 * fixup_init is called when:
357 * - an active object is initialized
359 static bool hrtimer_fixup_init(void *addr, enum debug_obj_state state)
361 struct hrtimer *timer = addr;
364 case ODEBUG_STATE_ACTIVE:
365 hrtimer_cancel(timer);
366 debug_object_init(timer, &hrtimer_debug_descr);
374 * fixup_activate is called when:
375 * - an active object is activated
376 * - an unknown non-static object is activated
378 static bool hrtimer_fixup_activate(void *addr, enum debug_obj_state state)
381 case ODEBUG_STATE_ACTIVE:
390 * fixup_free is called when:
391 * - an active object is freed
393 static bool hrtimer_fixup_free(void *addr, enum debug_obj_state state)
395 struct hrtimer *timer = addr;
398 case ODEBUG_STATE_ACTIVE:
399 hrtimer_cancel(timer);
400 debug_object_free(timer, &hrtimer_debug_descr);
407 static const struct debug_obj_descr hrtimer_debug_descr = {
409 .debug_hint = hrtimer_debug_hint,
410 .fixup_init = hrtimer_fixup_init,
411 .fixup_activate = hrtimer_fixup_activate,
412 .fixup_free = hrtimer_fixup_free,
415 static inline void debug_hrtimer_init(struct hrtimer *timer)
417 debug_object_init(timer, &hrtimer_debug_descr);
420 static inline void debug_hrtimer_activate(struct hrtimer *timer,
421 enum hrtimer_mode mode)
423 debug_object_activate(timer, &hrtimer_debug_descr);
426 static inline void debug_hrtimer_deactivate(struct hrtimer *timer)
428 debug_object_deactivate(timer, &hrtimer_debug_descr);
431 static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
432 enum hrtimer_mode mode);
434 void hrtimer_init_on_stack(struct hrtimer *timer, clockid_t clock_id,
435 enum hrtimer_mode mode)
437 debug_object_init_on_stack(timer, &hrtimer_debug_descr);
438 __hrtimer_init(timer, clock_id, mode);
440 EXPORT_SYMBOL_GPL(hrtimer_init_on_stack);
442 static void __hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
443 clockid_t clock_id, enum hrtimer_mode mode);
445 void hrtimer_init_sleeper_on_stack(struct hrtimer_sleeper *sl,
446 clockid_t clock_id, enum hrtimer_mode mode)
448 debug_object_init_on_stack(&sl->timer, &hrtimer_debug_descr);
449 __hrtimer_init_sleeper(sl, clock_id, mode);
451 EXPORT_SYMBOL_GPL(hrtimer_init_sleeper_on_stack);
453 void destroy_hrtimer_on_stack(struct hrtimer *timer)
455 debug_object_free(timer, &hrtimer_debug_descr);
457 EXPORT_SYMBOL_GPL(destroy_hrtimer_on_stack);
461 static inline void debug_hrtimer_init(struct hrtimer *timer) { }
462 static inline void debug_hrtimer_activate(struct hrtimer *timer,
463 enum hrtimer_mode mode) { }
464 static inline void debug_hrtimer_deactivate(struct hrtimer *timer) { }
468 debug_init(struct hrtimer *timer, clockid_t clockid,
469 enum hrtimer_mode mode)
471 debug_hrtimer_init(timer);
472 trace_hrtimer_init(timer, clockid, mode);
475 static inline void debug_activate(struct hrtimer *timer,
476 enum hrtimer_mode mode)
478 debug_hrtimer_activate(timer, mode);
479 trace_hrtimer_start(timer, mode);
482 static inline void debug_deactivate(struct hrtimer *timer)
484 debug_hrtimer_deactivate(timer);
485 trace_hrtimer_cancel(timer);
488 static struct hrtimer_clock_base *
489 __next_base(struct hrtimer_cpu_base *cpu_base, unsigned int *active)
496 idx = __ffs(*active);
497 *active &= ~(1U << idx);
499 return &cpu_base->clock_base[idx];
502 #define for_each_active_base(base, cpu_base, active) \
503 while ((base = __next_base((cpu_base), &(active))))
505 static ktime_t __hrtimer_next_event_base(struct hrtimer_cpu_base *cpu_base,
506 const struct hrtimer *exclude,
508 ktime_t expires_next)
510 struct hrtimer_clock_base *base;
513 for_each_active_base(base, cpu_base, active) {
514 struct timerqueue_node *next;
515 struct hrtimer *timer;
517 next = timerqueue_getnext(&base->active);
518 timer = container_of(next, struct hrtimer, node);
519 if (timer == exclude) {
520 /* Get to the next timer in the queue. */
521 next = timerqueue_iterate_next(next);
525 timer = container_of(next, struct hrtimer, node);
527 expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
528 if (expires < expires_next) {
529 expires_next = expires;
531 /* Skip cpu_base update if a timer is being excluded. */
536 cpu_base->softirq_next_timer = timer;
538 cpu_base->next_timer = timer;
542 * clock_was_set() might have changed base->offset of any of
543 * the clock bases so the result might be negative. Fix it up
544 * to prevent a false positive in clockevents_program_event().
546 if (expires_next < 0)
552 * Recomputes cpu_base::*next_timer and returns the earliest expires_next
553 * but does not set cpu_base::*expires_next, that is done by
554 * hrtimer[_force]_reprogram and hrtimer_interrupt only. When updating
555 * cpu_base::*expires_next right away, reprogramming logic would no longer
558 * When a softirq is pending, we can ignore the HRTIMER_ACTIVE_SOFT bases,
559 * those timers will get run whenever the softirq gets handled, at the end of
560 * hrtimer_run_softirq(), hrtimer_update_softirq_timer() will re-add these bases.
562 * Therefore softirq values are those from the HRTIMER_ACTIVE_SOFT clock bases.
563 * The !softirq values are the minima across HRTIMER_ACTIVE_ALL, unless an actual
564 * softirq is pending, in which case they're the minima of HRTIMER_ACTIVE_HARD.
566 * @active_mask must be one of:
567 * - HRTIMER_ACTIVE_ALL,
568 * - HRTIMER_ACTIVE_SOFT, or
569 * - HRTIMER_ACTIVE_HARD.
572 __hrtimer_get_next_event(struct hrtimer_cpu_base *cpu_base, unsigned int active_mask)
575 struct hrtimer *next_timer = NULL;
576 ktime_t expires_next = KTIME_MAX;
578 if (!cpu_base->softirq_activated && (active_mask & HRTIMER_ACTIVE_SOFT)) {
579 active = cpu_base->active_bases & HRTIMER_ACTIVE_SOFT;
580 cpu_base->softirq_next_timer = NULL;
581 expires_next = __hrtimer_next_event_base(cpu_base, NULL,
584 next_timer = cpu_base->softirq_next_timer;
587 if (active_mask & HRTIMER_ACTIVE_HARD) {
588 active = cpu_base->active_bases & HRTIMER_ACTIVE_HARD;
589 cpu_base->next_timer = next_timer;
590 expires_next = __hrtimer_next_event_base(cpu_base, NULL, active,
597 static ktime_t hrtimer_update_next_event(struct hrtimer_cpu_base *cpu_base)
599 ktime_t expires_next, soft = KTIME_MAX;
602 * If the soft interrupt has already been activated, ignore the
603 * soft bases. They will be handled in the already raised soft
606 if (!cpu_base->softirq_activated) {
607 soft = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_SOFT);
609 * Update the soft expiry time. clock_settime() might have
612 cpu_base->softirq_expires_next = soft;
615 expires_next = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_HARD);
617 * If a softirq timer is expiring first, update cpu_base->next_timer
618 * and program the hardware with the soft expiry time.
620 if (expires_next > soft) {
621 cpu_base->next_timer = cpu_base->softirq_next_timer;
628 static inline ktime_t hrtimer_update_base(struct hrtimer_cpu_base *base)
630 ktime_t *offs_real = &base->clock_base[HRTIMER_BASE_REALTIME].offset;
631 ktime_t *offs_boot = &base->clock_base[HRTIMER_BASE_BOOTTIME].offset;
632 ktime_t *offs_tai = &base->clock_base[HRTIMER_BASE_TAI].offset;
634 ktime_t now = ktime_get_update_offsets_now(&base->clock_was_set_seq,
635 offs_real, offs_boot, offs_tai);
637 base->clock_base[HRTIMER_BASE_REALTIME_SOFT].offset = *offs_real;
638 base->clock_base[HRTIMER_BASE_BOOTTIME_SOFT].offset = *offs_boot;
639 base->clock_base[HRTIMER_BASE_TAI_SOFT].offset = *offs_tai;
645 * Is the high resolution mode active ?
647 static inline int hrtimer_hres_active(struct hrtimer_cpu_base *cpu_base)
649 return IS_ENABLED(CONFIG_HIGH_RES_TIMERS) ?
650 cpu_base->hres_active : 0;
653 static void __hrtimer_reprogram(struct hrtimer_cpu_base *cpu_base,
654 struct hrtimer *next_timer,
655 ktime_t expires_next)
657 cpu_base->expires_next = expires_next;
660 * If hres is not active, hardware does not have to be
663 * If a hang was detected in the last timer interrupt then we
664 * leave the hang delay active in the hardware. We want the
665 * system to make progress. That also prevents the following
667 * T1 expires 50ms from now
668 * T2 expires 5s from now
670 * T1 is removed, so this code is called and would reprogram
671 * the hardware to 5s from now. Any hrtimer_start after that
672 * will not reprogram the hardware due to hang_detected being
673 * set. So we'd effectively block all timers until the T2 event
676 if (!hrtimer_hres_active(cpu_base) || cpu_base->hang_detected)
679 tick_program_event(expires_next, 1);
683 * Reprogram the event source with checking both queues for the
685 * Called with interrupts disabled and base->lock held
688 hrtimer_force_reprogram(struct hrtimer_cpu_base *cpu_base, int skip_equal)
690 ktime_t expires_next;
692 expires_next = hrtimer_update_next_event(cpu_base);
694 if (skip_equal && expires_next == cpu_base->expires_next)
697 __hrtimer_reprogram(cpu_base, cpu_base->next_timer, expires_next);
700 /* High resolution timer related functions */
701 #ifdef CONFIG_HIGH_RES_TIMERS
704 * High resolution timer enabled ?
706 static bool hrtimer_hres_enabled __read_mostly = true;
707 unsigned int hrtimer_resolution __read_mostly = LOW_RES_NSEC;
708 EXPORT_SYMBOL_GPL(hrtimer_resolution);
711 * Enable / Disable high resolution mode
713 static int __init setup_hrtimer_hres(char *str)
715 return (kstrtobool(str, &hrtimer_hres_enabled) == 0);
718 __setup("highres=", setup_hrtimer_hres);
721 * hrtimer_high_res_enabled - query, if the highres mode is enabled
723 static inline int hrtimer_is_hres_enabled(void)
725 return hrtimer_hres_enabled;
728 static void retrigger_next_event(void *arg);
731 * Switch to high resolution mode
733 static void hrtimer_switch_to_hres(void)
735 struct hrtimer_cpu_base *base = this_cpu_ptr(&hrtimer_bases);
737 if (tick_init_highres()) {
738 pr_warn("Could not switch to high resolution mode on CPU %u\n",
742 base->hres_active = 1;
743 hrtimer_resolution = HIGH_RES_NSEC;
745 tick_setup_sched_timer(true);
746 /* "Retrigger" the interrupt to get things going */
747 retrigger_next_event(NULL);
752 static inline int hrtimer_is_hres_enabled(void) { return 0; }
753 static inline void hrtimer_switch_to_hres(void) { }
755 #endif /* CONFIG_HIGH_RES_TIMERS */
757 * Retrigger next event is called after clock was set with interrupts
758 * disabled through an SMP function call or directly from low level
761 * This is only invoked when:
762 * - CONFIG_HIGH_RES_TIMERS is enabled.
763 * - CONFIG_NOHZ_COMMON is enabled
765 * For the other cases this function is empty and because the call sites
766 * are optimized out it vanishes as well, i.e. no need for lots of
769 static void retrigger_next_event(void *arg)
771 struct hrtimer_cpu_base *base = this_cpu_ptr(&hrtimer_bases);
774 * When high resolution mode or nohz is active, then the offsets of
775 * CLOCK_REALTIME/TAI/BOOTTIME have to be updated. Otherwise the
776 * next tick will take care of that.
778 * If high resolution mode is active then the next expiring timer
779 * must be reevaluated and the clock event device reprogrammed if
782 * In the NOHZ case the update of the offset and the reevaluation
783 * of the next expiring timer is enough. The return from the SMP
784 * function call will take care of the reprogramming in case the
785 * CPU was in a NOHZ idle sleep.
787 if (!hrtimer_hres_active(base) && !tick_nohz_active)
790 raw_spin_lock(&base->lock);
791 hrtimer_update_base(base);
792 if (hrtimer_hres_active(base))
793 hrtimer_force_reprogram(base, 0);
795 hrtimer_update_next_event(base);
796 raw_spin_unlock(&base->lock);
800 * When a timer is enqueued and expires earlier than the already enqueued
801 * timers, we have to check, whether it expires earlier than the timer for
802 * which the clock event device was armed.
804 * Called with interrupts disabled and base->cpu_base.lock held
806 static void hrtimer_reprogram(struct hrtimer *timer, bool reprogram)
808 struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
809 struct hrtimer_clock_base *base = timer->base;
810 ktime_t expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
812 WARN_ON_ONCE(hrtimer_get_expires_tv64(timer) < 0);
815 * CLOCK_REALTIME timer might be requested with an absolute
816 * expiry time which is less than base->offset. Set it to 0.
821 if (timer->is_soft) {
823 * soft hrtimer could be started on a remote CPU. In this
824 * case softirq_expires_next needs to be updated on the
825 * remote CPU. The soft hrtimer will not expire before the
826 * first hard hrtimer on the remote CPU -
827 * hrtimer_check_target() prevents this case.
829 struct hrtimer_cpu_base *timer_cpu_base = base->cpu_base;
831 if (timer_cpu_base->softirq_activated)
834 if (!ktime_before(expires, timer_cpu_base->softirq_expires_next))
837 timer_cpu_base->softirq_next_timer = timer;
838 timer_cpu_base->softirq_expires_next = expires;
840 if (!ktime_before(expires, timer_cpu_base->expires_next) ||
846 * If the timer is not on the current cpu, we cannot reprogram
847 * the other cpus clock event device.
849 if (base->cpu_base != cpu_base)
852 if (expires >= cpu_base->expires_next)
856 * If the hrtimer interrupt is running, then it will reevaluate the
857 * clock bases and reprogram the clock event device.
859 if (cpu_base->in_hrtirq)
862 cpu_base->next_timer = timer;
864 __hrtimer_reprogram(cpu_base, timer, expires);
867 static bool update_needs_ipi(struct hrtimer_cpu_base *cpu_base,
870 struct hrtimer_clock_base *base;
875 * Update the base offsets unconditionally so the following
876 * checks whether the SMP function call is required works.
878 * The update is safe even when the remote CPU is in the hrtimer
879 * interrupt or the hrtimer soft interrupt and expiring affected
880 * bases. Either it will see the update before handling a base or
881 * it will see it when it finishes the processing and reevaluates
882 * the next expiring timer.
884 seq = cpu_base->clock_was_set_seq;
885 hrtimer_update_base(cpu_base);
888 * If the sequence did not change over the update then the
889 * remote CPU already handled it.
891 if (seq == cpu_base->clock_was_set_seq)
895 * If the remote CPU is currently handling an hrtimer interrupt, it
896 * will reevaluate the first expiring timer of all clock bases
897 * before reprogramming. Nothing to do here.
899 if (cpu_base->in_hrtirq)
903 * Walk the affected clock bases and check whether the first expiring
904 * timer in a clock base is moving ahead of the first expiring timer of
905 * @cpu_base. If so, the IPI must be invoked because per CPU clock
906 * event devices cannot be remotely reprogrammed.
908 active &= cpu_base->active_bases;
910 for_each_active_base(base, cpu_base, active) {
911 struct timerqueue_node *next;
913 next = timerqueue_getnext(&base->active);
914 expires = ktime_sub(next->expires, base->offset);
915 if (expires < cpu_base->expires_next)
918 /* Extra check for softirq clock bases */
919 if (base->clockid < HRTIMER_BASE_MONOTONIC_SOFT)
921 if (cpu_base->softirq_activated)
923 if (expires < cpu_base->softirq_expires_next)
930 * Clock was set. This might affect CLOCK_REALTIME, CLOCK_TAI and
931 * CLOCK_BOOTTIME (for late sleep time injection).
933 * This requires to update the offsets for these clocks
934 * vs. CLOCK_MONOTONIC. When high resolution timers are enabled, then this
935 * also requires to eventually reprogram the per CPU clock event devices
936 * when the change moves an affected timer ahead of the first expiring
937 * timer on that CPU. Obviously remote per CPU clock event devices cannot
938 * be reprogrammed. The other reason why an IPI has to be sent is when the
939 * system is in !HIGH_RES and NOHZ mode. The NOHZ mode updates the offsets
940 * in the tick, which obviously might be stopped, so this has to bring out
941 * the remote CPU which might sleep in idle to get this sorted.
943 void clock_was_set(unsigned int bases)
945 struct hrtimer_cpu_base *cpu_base = raw_cpu_ptr(&hrtimer_bases);
949 if (!hrtimer_hres_active(cpu_base) && !tick_nohz_active)
952 if (!zalloc_cpumask_var(&mask, GFP_KERNEL)) {
953 on_each_cpu(retrigger_next_event, NULL, 1);
957 /* Avoid interrupting CPUs if possible */
959 for_each_online_cpu(cpu) {
962 cpu_base = &per_cpu(hrtimer_bases, cpu);
963 raw_spin_lock_irqsave(&cpu_base->lock, flags);
965 if (update_needs_ipi(cpu_base, bases))
966 cpumask_set_cpu(cpu, mask);
968 raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
972 smp_call_function_many(mask, retrigger_next_event, NULL, 1);
975 free_cpumask_var(mask);
978 timerfd_clock_was_set();
981 static void clock_was_set_work(struct work_struct *work)
983 clock_was_set(CLOCK_SET_WALL);
986 static DECLARE_WORK(hrtimer_work, clock_was_set_work);
989 * Called from timekeeping code to reprogram the hrtimer interrupt device
990 * on all cpus and to notify timerfd.
992 void clock_was_set_delayed(void)
994 schedule_work(&hrtimer_work);
998 * Called during resume either directly from via timekeeping_resume()
999 * or in the case of s2idle from tick_unfreeze() to ensure that the
1000 * hrtimers are up to date.
1002 void hrtimers_resume_local(void)
1004 lockdep_assert_irqs_disabled();
1005 /* Retrigger on the local CPU */
1006 retrigger_next_event(NULL);
1010 * Counterpart to lock_hrtimer_base above:
1013 void unlock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
1014 __releases(&timer->base->cpu_base->lock)
1016 raw_spin_unlock_irqrestore(&timer->base->cpu_base->lock, *flags);
1020 * hrtimer_forward() - forward the timer expiry
1021 * @timer: hrtimer to forward
1022 * @now: forward past this time
1023 * @interval: the interval to forward
1025 * Forward the timer expiry so it will expire in the future.
1028 * This only updates the timer expiry value and does not requeue the timer.
1030 * There is also a variant of the function hrtimer_forward_now().
1032 * Context: Can be safely called from the callback function of @timer. If called
1033 * from other contexts @timer must neither be enqueued nor running the
1034 * callback and the caller needs to take care of serialization.
1036 * Return: The number of overruns are returned.
1038 u64 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval)
1043 delta = ktime_sub(now, hrtimer_get_expires(timer));
1048 if (WARN_ON(timer->state & HRTIMER_STATE_ENQUEUED))
1051 if (interval < hrtimer_resolution)
1052 interval = hrtimer_resolution;
1054 if (unlikely(delta >= interval)) {
1055 s64 incr = ktime_to_ns(interval);
1057 orun = ktime_divns(delta, incr);
1058 hrtimer_add_expires_ns(timer, incr * orun);
1059 if (hrtimer_get_expires_tv64(timer) > now)
1062 * This (and the ktime_add() below) is the
1063 * correction for exact:
1067 hrtimer_add_expires(timer, interval);
1071 EXPORT_SYMBOL_GPL(hrtimer_forward);
1074 * enqueue_hrtimer - internal function to (re)start a timer
1076 * The timer is inserted in expiry order. Insertion into the
1077 * red black tree is O(log(n)). Must hold the base lock.
1079 * Returns 1 when the new timer is the leftmost timer in the tree.
1081 static int enqueue_hrtimer(struct hrtimer *timer,
1082 struct hrtimer_clock_base *base,
1083 enum hrtimer_mode mode)
1085 debug_activate(timer, mode);
1086 WARN_ON_ONCE(!base->cpu_base->online);
1088 base->cpu_base->active_bases |= 1 << base->index;
1090 /* Pairs with the lockless read in hrtimer_is_queued() */
1091 WRITE_ONCE(timer->state, HRTIMER_STATE_ENQUEUED);
1093 return timerqueue_add(&base->active, &timer->node);
1097 * __remove_hrtimer - internal function to remove a timer
1099 * Caller must hold the base lock.
1101 * High resolution timer mode reprograms the clock event device when the
1102 * timer is the one which expires next. The caller can disable this by setting
1103 * reprogram to zero. This is useful, when the context does a reprogramming
1104 * anyway (e.g. timer interrupt)
1106 static void __remove_hrtimer(struct hrtimer *timer,
1107 struct hrtimer_clock_base *base,
1108 u8 newstate, int reprogram)
1110 struct hrtimer_cpu_base *cpu_base = base->cpu_base;
1111 u8 state = timer->state;
1113 /* Pairs with the lockless read in hrtimer_is_queued() */
1114 WRITE_ONCE(timer->state, newstate);
1115 if (!(state & HRTIMER_STATE_ENQUEUED))
1118 if (!timerqueue_del(&base->active, &timer->node))
1119 cpu_base->active_bases &= ~(1 << base->index);
1122 * Note: If reprogram is false we do not update
1123 * cpu_base->next_timer. This happens when we remove the first
1124 * timer on a remote cpu. No harm as we never dereference
1125 * cpu_base->next_timer. So the worst thing what can happen is
1126 * an superfluous call to hrtimer_force_reprogram() on the
1127 * remote cpu later on if the same timer gets enqueued again.
1129 if (reprogram && timer == cpu_base->next_timer)
1130 hrtimer_force_reprogram(cpu_base, 1);
1134 * remove hrtimer, called with base lock held
1137 remove_hrtimer(struct hrtimer *timer, struct hrtimer_clock_base *base,
1138 bool restart, bool keep_local)
1140 u8 state = timer->state;
1142 if (state & HRTIMER_STATE_ENQUEUED) {
1146 * Remove the timer and force reprogramming when high
1147 * resolution mode is active and the timer is on the current
1148 * CPU. If we remove a timer on another CPU, reprogramming is
1149 * skipped. The interrupt event on this CPU is fired and
1150 * reprogramming happens in the interrupt handler. This is a
1151 * rare case and less expensive than a smp call.
1153 debug_deactivate(timer);
1154 reprogram = base->cpu_base == this_cpu_ptr(&hrtimer_bases);
1157 * If the timer is not restarted then reprogramming is
1158 * required if the timer is local. If it is local and about
1159 * to be restarted, avoid programming it twice (on removal
1160 * and a moment later when it's requeued).
1163 state = HRTIMER_STATE_INACTIVE;
1165 reprogram &= !keep_local;
1167 __remove_hrtimer(timer, base, state, reprogram);
1173 static inline ktime_t hrtimer_update_lowres(struct hrtimer *timer, ktime_t tim,
1174 const enum hrtimer_mode mode)
1176 #ifdef CONFIG_TIME_LOW_RES
1178 * CONFIG_TIME_LOW_RES indicates that the system has no way to return
1179 * granular time values. For relative timers we add hrtimer_resolution
1180 * (i.e. one jiffie) to prevent short timeouts.
1182 timer->is_rel = mode & HRTIMER_MODE_REL;
1184 tim = ktime_add_safe(tim, hrtimer_resolution);
1190 hrtimer_update_softirq_timer(struct hrtimer_cpu_base *cpu_base, bool reprogram)
1195 * Find the next SOFT expiration.
1197 expires = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_SOFT);
1200 * reprogramming needs to be triggered, even if the next soft
1201 * hrtimer expires at the same time than the next hard
1202 * hrtimer. cpu_base->softirq_expires_next needs to be updated!
1204 if (expires == KTIME_MAX)
1208 * cpu_base->*next_timer is recomputed by __hrtimer_get_next_event()
1209 * cpu_base->*expires_next is only set by hrtimer_reprogram()
1211 hrtimer_reprogram(cpu_base->softirq_next_timer, reprogram);
1214 static int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
1215 u64 delta_ns, const enum hrtimer_mode mode,
1216 struct hrtimer_clock_base *base)
1218 struct hrtimer_clock_base *new_base;
1219 bool force_local, first;
1222 * If the timer is on the local cpu base and is the first expiring
1223 * timer then this might end up reprogramming the hardware twice
1224 * (on removal and on enqueue). To avoid that by prevent the
1225 * reprogram on removal, keep the timer local to the current CPU
1226 * and enforce reprogramming after it is queued no matter whether
1227 * it is the new first expiring timer again or not.
1229 force_local = base->cpu_base == this_cpu_ptr(&hrtimer_bases);
1230 force_local &= base->cpu_base->next_timer == timer;
1233 * Remove an active timer from the queue. In case it is not queued
1234 * on the current CPU, make sure that remove_hrtimer() updates the
1235 * remote data correctly.
1237 * If it's on the current CPU and the first expiring timer, then
1238 * skip reprogramming, keep the timer local and enforce
1239 * reprogramming later if it was the first expiring timer. This
1240 * avoids programming the underlying clock event twice (once at
1241 * removal and once after enqueue).
1243 remove_hrtimer(timer, base, true, force_local);
1245 if (mode & HRTIMER_MODE_REL)
1246 tim = ktime_add_safe(tim, base->get_time());
1248 tim = hrtimer_update_lowres(timer, tim, mode);
1250 hrtimer_set_expires_range_ns(timer, tim, delta_ns);
1252 /* Switch the timer base, if necessary: */
1254 new_base = switch_hrtimer_base(timer, base,
1255 mode & HRTIMER_MODE_PINNED);
1260 first = enqueue_hrtimer(timer, new_base, mode);
1265 * Timer was forced to stay on the current CPU to avoid
1266 * reprogramming on removal and enqueue. Force reprogram the
1267 * hardware by evaluating the new first expiring timer.
1269 hrtimer_force_reprogram(new_base->cpu_base, 1);
1274 * hrtimer_start_range_ns - (re)start an hrtimer
1275 * @timer: the timer to be added
1277 * @delta_ns: "slack" range for the timer
1278 * @mode: timer mode: absolute (HRTIMER_MODE_ABS) or
1279 * relative (HRTIMER_MODE_REL), and pinned (HRTIMER_MODE_PINNED);
1280 * softirq based mode is considered for debug purpose only!
1282 void hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
1283 u64 delta_ns, const enum hrtimer_mode mode)
1285 struct hrtimer_clock_base *base;
1286 unsigned long flags;
1289 * Check whether the HRTIMER_MODE_SOFT bit and hrtimer.is_soft
1290 * match on CONFIG_PREEMPT_RT = n. With PREEMPT_RT check the hard
1291 * expiry mode because unmarked timers are moved to softirq expiry.
1293 if (!IS_ENABLED(CONFIG_PREEMPT_RT))
1294 WARN_ON_ONCE(!(mode & HRTIMER_MODE_SOFT) ^ !timer->is_soft);
1296 WARN_ON_ONCE(!(mode & HRTIMER_MODE_HARD) ^ !timer->is_hard);
1298 base = lock_hrtimer_base(timer, &flags);
1300 if (__hrtimer_start_range_ns(timer, tim, delta_ns, mode, base))
1301 hrtimer_reprogram(timer, true);
1303 unlock_hrtimer_base(timer, &flags);
1305 EXPORT_SYMBOL_GPL(hrtimer_start_range_ns);
1308 * hrtimer_try_to_cancel - try to deactivate a timer
1309 * @timer: hrtimer to stop
1313 * * 0 when the timer was not active
1314 * * 1 when the timer was active
1315 * * -1 when the timer is currently executing the callback function and
1318 int hrtimer_try_to_cancel(struct hrtimer *timer)
1320 struct hrtimer_clock_base *base;
1321 unsigned long flags;
1325 * Check lockless first. If the timer is not active (neither
1326 * enqueued nor running the callback, nothing to do here. The
1327 * base lock does not serialize against a concurrent enqueue,
1328 * so we can avoid taking it.
1330 if (!hrtimer_active(timer))
1333 base = lock_hrtimer_base(timer, &flags);
1335 if (!hrtimer_callback_running(timer))
1336 ret = remove_hrtimer(timer, base, false, false);
1338 unlock_hrtimer_base(timer, &flags);
1343 EXPORT_SYMBOL_GPL(hrtimer_try_to_cancel);
1345 #ifdef CONFIG_PREEMPT_RT
1346 static void hrtimer_cpu_base_init_expiry_lock(struct hrtimer_cpu_base *base)
1348 spin_lock_init(&base->softirq_expiry_lock);
1351 static void hrtimer_cpu_base_lock_expiry(struct hrtimer_cpu_base *base)
1353 spin_lock(&base->softirq_expiry_lock);
1356 static void hrtimer_cpu_base_unlock_expiry(struct hrtimer_cpu_base *base)
1358 spin_unlock(&base->softirq_expiry_lock);
1362 * The counterpart to hrtimer_cancel_wait_running().
1364 * If there is a waiter for cpu_base->expiry_lock, then it was waiting for
1365 * the timer callback to finish. Drop expiry_lock and reacquire it. That
1366 * allows the waiter to acquire the lock and make progress.
1368 static void hrtimer_sync_wait_running(struct hrtimer_cpu_base *cpu_base,
1369 unsigned long flags)
1371 if (atomic_read(&cpu_base->timer_waiters)) {
1372 raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1373 spin_unlock(&cpu_base->softirq_expiry_lock);
1374 spin_lock(&cpu_base->softirq_expiry_lock);
1375 raw_spin_lock_irq(&cpu_base->lock);
1380 * This function is called on PREEMPT_RT kernels when the fast path
1381 * deletion of a timer failed because the timer callback function was
1384 * This prevents priority inversion: if the soft irq thread is preempted
1385 * in the middle of a timer callback, then calling del_timer_sync() can
1386 * lead to two issues:
1388 * - If the caller is on a remote CPU then it has to spin wait for the timer
1389 * handler to complete. This can result in unbound priority inversion.
1391 * - If the caller originates from the task which preempted the timer
1392 * handler on the same CPU, then spin waiting for the timer handler to
1393 * complete is never going to end.
1395 void hrtimer_cancel_wait_running(const struct hrtimer *timer)
1397 /* Lockless read. Prevent the compiler from reloading it below */
1398 struct hrtimer_clock_base *base = READ_ONCE(timer->base);
1401 * Just relax if the timer expires in hard interrupt context or if
1402 * it is currently on the migration base.
1404 if (!timer->is_soft || is_migration_base(base)) {
1410 * Mark the base as contended and grab the expiry lock, which is
1411 * held by the softirq across the timer callback. Drop the lock
1412 * immediately so the softirq can expire the next timer. In theory
1413 * the timer could already be running again, but that's more than
1414 * unlikely and just causes another wait loop.
1416 atomic_inc(&base->cpu_base->timer_waiters);
1417 spin_lock_bh(&base->cpu_base->softirq_expiry_lock);
1418 atomic_dec(&base->cpu_base->timer_waiters);
1419 spin_unlock_bh(&base->cpu_base->softirq_expiry_lock);
1423 hrtimer_cpu_base_init_expiry_lock(struct hrtimer_cpu_base *base) { }
1425 hrtimer_cpu_base_lock_expiry(struct hrtimer_cpu_base *base) { }
1427 hrtimer_cpu_base_unlock_expiry(struct hrtimer_cpu_base *base) { }
1428 static inline void hrtimer_sync_wait_running(struct hrtimer_cpu_base *base,
1429 unsigned long flags) { }
1433 * hrtimer_cancel - cancel a timer and wait for the handler to finish.
1434 * @timer: the timer to be cancelled
1437 * 0 when the timer was not active
1438 * 1 when the timer was active
1440 int hrtimer_cancel(struct hrtimer *timer)
1445 ret = hrtimer_try_to_cancel(timer);
1448 hrtimer_cancel_wait_running(timer);
1452 EXPORT_SYMBOL_GPL(hrtimer_cancel);
1455 * __hrtimer_get_remaining - get remaining time for the timer
1456 * @timer: the timer to read
1457 * @adjust: adjust relative timers when CONFIG_TIME_LOW_RES=y
1459 ktime_t __hrtimer_get_remaining(const struct hrtimer *timer, bool adjust)
1461 unsigned long flags;
1464 lock_hrtimer_base(timer, &flags);
1465 if (IS_ENABLED(CONFIG_TIME_LOW_RES) && adjust)
1466 rem = hrtimer_expires_remaining_adjusted(timer);
1468 rem = hrtimer_expires_remaining(timer);
1469 unlock_hrtimer_base(timer, &flags);
1473 EXPORT_SYMBOL_GPL(__hrtimer_get_remaining);
1475 #ifdef CONFIG_NO_HZ_COMMON
1477 * hrtimer_get_next_event - get the time until next expiry event
1479 * Returns the next expiry time or KTIME_MAX if no timer is pending.
1481 u64 hrtimer_get_next_event(void)
1483 struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1484 u64 expires = KTIME_MAX;
1485 unsigned long flags;
1487 raw_spin_lock_irqsave(&cpu_base->lock, flags);
1489 if (!hrtimer_hres_active(cpu_base))
1490 expires = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_ALL);
1492 raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1498 * hrtimer_next_event_without - time until next expiry event w/o one timer
1499 * @exclude: timer to exclude
1501 * Returns the next expiry time over all timers except for the @exclude one or
1502 * KTIME_MAX if none of them is pending.
1504 u64 hrtimer_next_event_without(const struct hrtimer *exclude)
1506 struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1507 u64 expires = KTIME_MAX;
1508 unsigned long flags;
1510 raw_spin_lock_irqsave(&cpu_base->lock, flags);
1512 if (hrtimer_hres_active(cpu_base)) {
1513 unsigned int active;
1515 if (!cpu_base->softirq_activated) {
1516 active = cpu_base->active_bases & HRTIMER_ACTIVE_SOFT;
1517 expires = __hrtimer_next_event_base(cpu_base, exclude,
1520 active = cpu_base->active_bases & HRTIMER_ACTIVE_HARD;
1521 expires = __hrtimer_next_event_base(cpu_base, exclude, active,
1525 raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1531 static inline int hrtimer_clockid_to_base(clockid_t clock_id)
1533 if (likely(clock_id < MAX_CLOCKS)) {
1534 int base = hrtimer_clock_to_base_table[clock_id];
1536 if (likely(base != HRTIMER_MAX_CLOCK_BASES))
1539 WARN(1, "Invalid clockid %d. Using MONOTONIC\n", clock_id);
1540 return HRTIMER_BASE_MONOTONIC;
1543 static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
1544 enum hrtimer_mode mode)
1546 bool softtimer = !!(mode & HRTIMER_MODE_SOFT);
1547 struct hrtimer_cpu_base *cpu_base;
1551 * On PREEMPT_RT enabled kernels hrtimers which are not explicitly
1552 * marked for hard interrupt expiry mode are moved into soft
1553 * interrupt context for latency reasons and because the callbacks
1554 * can invoke functions which might sleep on RT, e.g. spin_lock().
1556 if (IS_ENABLED(CONFIG_PREEMPT_RT) && !(mode & HRTIMER_MODE_HARD))
1559 memset(timer, 0, sizeof(struct hrtimer));
1561 cpu_base = raw_cpu_ptr(&hrtimer_bases);
1564 * POSIX magic: Relative CLOCK_REALTIME timers are not affected by
1565 * clock modifications, so they needs to become CLOCK_MONOTONIC to
1566 * ensure POSIX compliance.
1568 if (clock_id == CLOCK_REALTIME && mode & HRTIMER_MODE_REL)
1569 clock_id = CLOCK_MONOTONIC;
1571 base = softtimer ? HRTIMER_MAX_CLOCK_BASES / 2 : 0;
1572 base += hrtimer_clockid_to_base(clock_id);
1573 timer->is_soft = softtimer;
1574 timer->is_hard = !!(mode & HRTIMER_MODE_HARD);
1575 timer->base = &cpu_base->clock_base[base];
1576 timerqueue_init(&timer->node);
1580 * hrtimer_init - initialize a timer to the given clock
1581 * @timer: the timer to be initialized
1582 * @clock_id: the clock to be used
1583 * @mode: The modes which are relevant for initialization:
1584 * HRTIMER_MODE_ABS, HRTIMER_MODE_REL, HRTIMER_MODE_ABS_SOFT,
1585 * HRTIMER_MODE_REL_SOFT
1587 * The PINNED variants of the above can be handed in,
1588 * but the PINNED bit is ignored as pinning happens
1589 * when the hrtimer is started
1591 void hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
1592 enum hrtimer_mode mode)
1594 debug_init(timer, clock_id, mode);
1595 __hrtimer_init(timer, clock_id, mode);
1597 EXPORT_SYMBOL_GPL(hrtimer_init);
1600 * A timer is active, when it is enqueued into the rbtree or the
1601 * callback function is running or it's in the state of being migrated
1604 * It is important for this function to not return a false negative.
1606 bool hrtimer_active(const struct hrtimer *timer)
1608 struct hrtimer_clock_base *base;
1612 base = READ_ONCE(timer->base);
1613 seq = raw_read_seqcount_begin(&base->seq);
1615 if (timer->state != HRTIMER_STATE_INACTIVE ||
1616 base->running == timer)
1619 } while (read_seqcount_retry(&base->seq, seq) ||
1620 base != READ_ONCE(timer->base));
1624 EXPORT_SYMBOL_GPL(hrtimer_active);
1627 * The write_seqcount_barrier()s in __run_hrtimer() split the thing into 3
1628 * distinct sections:
1630 * - queued: the timer is queued
1631 * - callback: the timer is being ran
1632 * - post: the timer is inactive or (re)queued
1634 * On the read side we ensure we observe timer->state and cpu_base->running
1635 * from the same section, if anything changed while we looked at it, we retry.
1636 * This includes timer->base changing because sequence numbers alone are
1637 * insufficient for that.
1639 * The sequence numbers are required because otherwise we could still observe
1640 * a false negative if the read side got smeared over multiple consecutive
1641 * __run_hrtimer() invocations.
1644 static void __run_hrtimer(struct hrtimer_cpu_base *cpu_base,
1645 struct hrtimer_clock_base *base,
1646 struct hrtimer *timer, ktime_t *now,
1647 unsigned long flags) __must_hold(&cpu_base->lock)
1649 enum hrtimer_restart (*fn)(struct hrtimer *);
1650 bool expires_in_hardirq;
1653 lockdep_assert_held(&cpu_base->lock);
1655 debug_deactivate(timer);
1656 base->running = timer;
1659 * Separate the ->running assignment from the ->state assignment.
1661 * As with a regular write barrier, this ensures the read side in
1662 * hrtimer_active() cannot observe base->running == NULL &&
1663 * timer->state == INACTIVE.
1665 raw_write_seqcount_barrier(&base->seq);
1667 __remove_hrtimer(timer, base, HRTIMER_STATE_INACTIVE, 0);
1668 fn = timer->function;
1671 * Clear the 'is relative' flag for the TIME_LOW_RES case. If the
1672 * timer is restarted with a period then it becomes an absolute
1673 * timer. If its not restarted it does not matter.
1675 if (IS_ENABLED(CONFIG_TIME_LOW_RES))
1676 timer->is_rel = false;
1679 * The timer is marked as running in the CPU base, so it is
1680 * protected against migration to a different CPU even if the lock
1683 raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1684 trace_hrtimer_expire_entry(timer, now);
1685 expires_in_hardirq = lockdep_hrtimer_enter(timer);
1687 restart = fn(timer);
1689 lockdep_hrtimer_exit(expires_in_hardirq);
1690 trace_hrtimer_expire_exit(timer);
1691 raw_spin_lock_irq(&cpu_base->lock);
1694 * Note: We clear the running state after enqueue_hrtimer and
1695 * we do not reprogram the event hardware. Happens either in
1696 * hrtimer_start_range_ns() or in hrtimer_interrupt()
1698 * Note: Because we dropped the cpu_base->lock above,
1699 * hrtimer_start_range_ns() can have popped in and enqueued the timer
1702 if (restart != HRTIMER_NORESTART &&
1703 !(timer->state & HRTIMER_STATE_ENQUEUED))
1704 enqueue_hrtimer(timer, base, HRTIMER_MODE_ABS);
1707 * Separate the ->running assignment from the ->state assignment.
1709 * As with a regular write barrier, this ensures the read side in
1710 * hrtimer_active() cannot observe base->running.timer == NULL &&
1711 * timer->state == INACTIVE.
1713 raw_write_seqcount_barrier(&base->seq);
1715 WARN_ON_ONCE(base->running != timer);
1716 base->running = NULL;
1719 static void __hrtimer_run_queues(struct hrtimer_cpu_base *cpu_base, ktime_t now,
1720 unsigned long flags, unsigned int active_mask)
1722 struct hrtimer_clock_base *base;
1723 unsigned int active = cpu_base->active_bases & active_mask;
1725 for_each_active_base(base, cpu_base, active) {
1726 struct timerqueue_node *node;
1729 basenow = ktime_add(now, base->offset);
1731 while ((node = timerqueue_getnext(&base->active))) {
1732 struct hrtimer *timer;
1734 timer = container_of(node, struct hrtimer, node);
1737 * The immediate goal for using the softexpires is
1738 * minimizing wakeups, not running timers at the
1739 * earliest interrupt after their soft expiration.
1740 * This allows us to avoid using a Priority Search
1741 * Tree, which can answer a stabbing query for
1742 * overlapping intervals and instead use the simple
1743 * BST we already have.
1744 * We don't add extra wakeups by delaying timers that
1745 * are right-of a not yet expired timer, because that
1746 * timer will have to trigger a wakeup anyway.
1748 if (basenow < hrtimer_get_softexpires_tv64(timer))
1751 __run_hrtimer(cpu_base, base, timer, &basenow, flags);
1752 if (active_mask == HRTIMER_ACTIVE_SOFT)
1753 hrtimer_sync_wait_running(cpu_base, flags);
1758 static __latent_entropy void hrtimer_run_softirq(struct softirq_action *h)
1760 struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1761 unsigned long flags;
1764 hrtimer_cpu_base_lock_expiry(cpu_base);
1765 raw_spin_lock_irqsave(&cpu_base->lock, flags);
1767 now = hrtimer_update_base(cpu_base);
1768 __hrtimer_run_queues(cpu_base, now, flags, HRTIMER_ACTIVE_SOFT);
1770 cpu_base->softirq_activated = 0;
1771 hrtimer_update_softirq_timer(cpu_base, true);
1773 raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1774 hrtimer_cpu_base_unlock_expiry(cpu_base);
1777 #ifdef CONFIG_HIGH_RES_TIMERS
1780 * High resolution timer interrupt
1781 * Called with interrupts disabled
1783 void hrtimer_interrupt(struct clock_event_device *dev)
1785 struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1786 ktime_t expires_next, now, entry_time, delta;
1787 unsigned long flags;
1790 BUG_ON(!cpu_base->hres_active);
1791 cpu_base->nr_events++;
1792 dev->next_event = KTIME_MAX;
1794 raw_spin_lock_irqsave(&cpu_base->lock, flags);
1795 entry_time = now = hrtimer_update_base(cpu_base);
1797 cpu_base->in_hrtirq = 1;
1799 * We set expires_next to KTIME_MAX here with cpu_base->lock
1800 * held to prevent that a timer is enqueued in our queue via
1801 * the migration code. This does not affect enqueueing of
1802 * timers which run their callback and need to be requeued on
1805 cpu_base->expires_next = KTIME_MAX;
1807 if (!ktime_before(now, cpu_base->softirq_expires_next)) {
1808 cpu_base->softirq_expires_next = KTIME_MAX;
1809 cpu_base->softirq_activated = 1;
1810 raise_softirq_irqoff(HRTIMER_SOFTIRQ);
1813 __hrtimer_run_queues(cpu_base, now, flags, HRTIMER_ACTIVE_HARD);
1815 /* Reevaluate the clock bases for the [soft] next expiry */
1816 expires_next = hrtimer_update_next_event(cpu_base);
1818 * Store the new expiry value so the migration code can verify
1821 cpu_base->expires_next = expires_next;
1822 cpu_base->in_hrtirq = 0;
1823 raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1825 /* Reprogramming necessary ? */
1826 if (!tick_program_event(expires_next, 0)) {
1827 cpu_base->hang_detected = 0;
1832 * The next timer was already expired due to:
1834 * - long lasting callbacks
1835 * - being scheduled away when running in a VM
1837 * We need to prevent that we loop forever in the hrtimer
1838 * interrupt routine. We give it 3 attempts to avoid
1839 * overreacting on some spurious event.
1841 * Acquire base lock for updating the offsets and retrieving
1844 raw_spin_lock_irqsave(&cpu_base->lock, flags);
1845 now = hrtimer_update_base(cpu_base);
1846 cpu_base->nr_retries++;
1850 * Give the system a chance to do something else than looping
1851 * here. We stored the entry time, so we know exactly how long
1852 * we spent here. We schedule the next event this amount of
1855 cpu_base->nr_hangs++;
1856 cpu_base->hang_detected = 1;
1857 raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1859 delta = ktime_sub(now, entry_time);
1860 if ((unsigned int)delta > cpu_base->max_hang_time)
1861 cpu_base->max_hang_time = (unsigned int) delta;
1863 * Limit it to a sensible value as we enforce a longer
1864 * delay. Give the CPU at least 100ms to catch up.
1866 if (delta > 100 * NSEC_PER_MSEC)
1867 expires_next = ktime_add_ns(now, 100 * NSEC_PER_MSEC);
1869 expires_next = ktime_add(now, delta);
1870 tick_program_event(expires_next, 1);
1871 pr_warn_once("hrtimer: interrupt took %llu ns\n", ktime_to_ns(delta));
1873 #endif /* !CONFIG_HIGH_RES_TIMERS */
1876 * Called from run_local_timers in hardirq context every jiffy
1878 void hrtimer_run_queues(void)
1880 struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1881 unsigned long flags;
1884 if (hrtimer_hres_active(cpu_base))
1888 * This _is_ ugly: We have to check periodically, whether we
1889 * can switch to highres and / or nohz mode. The clocksource
1890 * switch happens with xtime_lock held. Notification from
1891 * there only sets the check bit in the tick_oneshot code,
1892 * otherwise we might deadlock vs. xtime_lock.
1894 if (tick_check_oneshot_change(!hrtimer_is_hres_enabled())) {
1895 hrtimer_switch_to_hres();
1899 raw_spin_lock_irqsave(&cpu_base->lock, flags);
1900 now = hrtimer_update_base(cpu_base);
1902 if (!ktime_before(now, cpu_base->softirq_expires_next)) {
1903 cpu_base->softirq_expires_next = KTIME_MAX;
1904 cpu_base->softirq_activated = 1;
1905 raise_softirq_irqoff(HRTIMER_SOFTIRQ);
1908 __hrtimer_run_queues(cpu_base, now, flags, HRTIMER_ACTIVE_HARD);
1909 raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1913 * Sleep related functions:
1915 static enum hrtimer_restart hrtimer_wakeup(struct hrtimer *timer)
1917 struct hrtimer_sleeper *t =
1918 container_of(timer, struct hrtimer_sleeper, timer);
1919 struct task_struct *task = t->task;
1923 wake_up_process(task);
1925 return HRTIMER_NORESTART;
1929 * hrtimer_sleeper_start_expires - Start a hrtimer sleeper timer
1930 * @sl: sleeper to be started
1931 * @mode: timer mode abs/rel
1933 * Wrapper around hrtimer_start_expires() for hrtimer_sleeper based timers
1934 * to allow PREEMPT_RT to tweak the delivery mode (soft/hardirq context)
1936 void hrtimer_sleeper_start_expires(struct hrtimer_sleeper *sl,
1937 enum hrtimer_mode mode)
1940 * Make the enqueue delivery mode check work on RT. If the sleeper
1941 * was initialized for hard interrupt delivery, force the mode bit.
1942 * This is a special case for hrtimer_sleepers because
1943 * hrtimer_init_sleeper() determines the delivery mode on RT so the
1944 * fiddling with this decision is avoided at the call sites.
1946 if (IS_ENABLED(CONFIG_PREEMPT_RT) && sl->timer.is_hard)
1947 mode |= HRTIMER_MODE_HARD;
1949 hrtimer_start_expires(&sl->timer, mode);
1951 EXPORT_SYMBOL_GPL(hrtimer_sleeper_start_expires);
1953 static void __hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
1954 clockid_t clock_id, enum hrtimer_mode mode)
1957 * On PREEMPT_RT enabled kernels hrtimers which are not explicitly
1958 * marked for hard interrupt expiry mode are moved into soft
1959 * interrupt context either for latency reasons or because the
1960 * hrtimer callback takes regular spinlocks or invokes other
1961 * functions which are not suitable for hard interrupt context on
1964 * The hrtimer_sleeper callback is RT compatible in hard interrupt
1965 * context, but there is a latency concern: Untrusted userspace can
1966 * spawn many threads which arm timers for the same expiry time on
1967 * the same CPU. That causes a latency spike due to the wakeup of
1968 * a gazillion threads.
1970 * OTOH, privileged real-time user space applications rely on the
1971 * low latency of hard interrupt wakeups. If the current task is in
1972 * a real-time scheduling class, mark the mode for hard interrupt
1975 if (IS_ENABLED(CONFIG_PREEMPT_RT)) {
1976 if (task_is_realtime(current) && !(mode & HRTIMER_MODE_SOFT))
1977 mode |= HRTIMER_MODE_HARD;
1980 __hrtimer_init(&sl->timer, clock_id, mode);
1981 sl->timer.function = hrtimer_wakeup;
1986 * hrtimer_init_sleeper - initialize sleeper to the given clock
1987 * @sl: sleeper to be initialized
1988 * @clock_id: the clock to be used
1989 * @mode: timer mode abs/rel
1991 void hrtimer_init_sleeper(struct hrtimer_sleeper *sl, clockid_t clock_id,
1992 enum hrtimer_mode mode)
1994 debug_init(&sl->timer, clock_id, mode);
1995 __hrtimer_init_sleeper(sl, clock_id, mode);
1998 EXPORT_SYMBOL_GPL(hrtimer_init_sleeper);
2000 int nanosleep_copyout(struct restart_block *restart, struct timespec64 *ts)
2002 switch(restart->nanosleep.type) {
2003 #ifdef CONFIG_COMPAT_32BIT_TIME
2005 if (put_old_timespec32(ts, restart->nanosleep.compat_rmtp))
2010 if (put_timespec64(ts, restart->nanosleep.rmtp))
2016 return -ERESTART_RESTARTBLOCK;
2019 static int __sched do_nanosleep(struct hrtimer_sleeper *t, enum hrtimer_mode mode)
2021 struct restart_block *restart;
2024 set_current_state(TASK_INTERRUPTIBLE|TASK_FREEZABLE);
2025 hrtimer_sleeper_start_expires(t, mode);
2027 if (likely(t->task))
2030 hrtimer_cancel(&t->timer);
2031 mode = HRTIMER_MODE_ABS;
2033 } while (t->task && !signal_pending(current));
2035 __set_current_state(TASK_RUNNING);
2040 restart = ¤t->restart_block;
2041 if (restart->nanosleep.type != TT_NONE) {
2042 ktime_t rem = hrtimer_expires_remaining(&t->timer);
2043 struct timespec64 rmt;
2047 rmt = ktime_to_timespec64(rem);
2049 return nanosleep_copyout(restart, &rmt);
2051 return -ERESTART_RESTARTBLOCK;
2054 static long __sched hrtimer_nanosleep_restart(struct restart_block *restart)
2056 struct hrtimer_sleeper t;
2059 hrtimer_init_sleeper_on_stack(&t, restart->nanosleep.clockid,
2061 hrtimer_set_expires_tv64(&t.timer, restart->nanosleep.expires);
2062 ret = do_nanosleep(&t, HRTIMER_MODE_ABS);
2063 destroy_hrtimer_on_stack(&t.timer);
2067 long hrtimer_nanosleep(ktime_t rqtp, const enum hrtimer_mode mode,
2068 const clockid_t clockid)
2070 struct restart_block *restart;
2071 struct hrtimer_sleeper t;
2075 slack = current->timer_slack_ns;
2076 if (rt_task(current))
2079 hrtimer_init_sleeper_on_stack(&t, clockid, mode);
2080 hrtimer_set_expires_range_ns(&t.timer, rqtp, slack);
2081 ret = do_nanosleep(&t, mode);
2082 if (ret != -ERESTART_RESTARTBLOCK)
2085 /* Absolute timers do not update the rmtp value and restart: */
2086 if (mode == HRTIMER_MODE_ABS) {
2087 ret = -ERESTARTNOHAND;
2091 restart = ¤t->restart_block;
2092 restart->nanosleep.clockid = t.timer.base->clockid;
2093 restart->nanosleep.expires = hrtimer_get_expires_tv64(&t.timer);
2094 set_restart_fn(restart, hrtimer_nanosleep_restart);
2096 destroy_hrtimer_on_stack(&t.timer);
2102 SYSCALL_DEFINE2(nanosleep, struct __kernel_timespec __user *, rqtp,
2103 struct __kernel_timespec __user *, rmtp)
2105 struct timespec64 tu;
2107 if (get_timespec64(&tu, rqtp))
2110 if (!timespec64_valid(&tu))
2113 current->restart_block.fn = do_no_restart_syscall;
2114 current->restart_block.nanosleep.type = rmtp ? TT_NATIVE : TT_NONE;
2115 current->restart_block.nanosleep.rmtp = rmtp;
2116 return hrtimer_nanosleep(timespec64_to_ktime(tu), HRTIMER_MODE_REL,
2122 #ifdef CONFIG_COMPAT_32BIT_TIME
2124 SYSCALL_DEFINE2(nanosleep_time32, struct old_timespec32 __user *, rqtp,
2125 struct old_timespec32 __user *, rmtp)
2127 struct timespec64 tu;
2129 if (get_old_timespec32(&tu, rqtp))
2132 if (!timespec64_valid(&tu))
2135 current->restart_block.fn = do_no_restart_syscall;
2136 current->restart_block.nanosleep.type = rmtp ? TT_COMPAT : TT_NONE;
2137 current->restart_block.nanosleep.compat_rmtp = rmtp;
2138 return hrtimer_nanosleep(timespec64_to_ktime(tu), HRTIMER_MODE_REL,
2144 * Functions related to boot-time initialization:
2146 int hrtimers_prepare_cpu(unsigned int cpu)
2148 struct hrtimer_cpu_base *cpu_base = &per_cpu(hrtimer_bases, cpu);
2151 for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
2152 struct hrtimer_clock_base *clock_b = &cpu_base->clock_base[i];
2154 clock_b->cpu_base = cpu_base;
2155 seqcount_raw_spinlock_init(&clock_b->seq, &cpu_base->lock);
2156 timerqueue_init_head(&clock_b->active);
2159 cpu_base->cpu = cpu;
2160 cpu_base->active_bases = 0;
2161 cpu_base->hres_active = 0;
2162 cpu_base->hang_detected = 0;
2163 cpu_base->next_timer = NULL;
2164 cpu_base->softirq_next_timer = NULL;
2165 cpu_base->expires_next = KTIME_MAX;
2166 cpu_base->softirq_expires_next = KTIME_MAX;
2167 cpu_base->online = 1;
2168 hrtimer_cpu_base_init_expiry_lock(cpu_base);
2172 #ifdef CONFIG_HOTPLUG_CPU
2174 static void migrate_hrtimer_list(struct hrtimer_clock_base *old_base,
2175 struct hrtimer_clock_base *new_base)
2177 struct hrtimer *timer;
2178 struct timerqueue_node *node;
2180 while ((node = timerqueue_getnext(&old_base->active))) {
2181 timer = container_of(node, struct hrtimer, node);
2182 BUG_ON(hrtimer_callback_running(timer));
2183 debug_deactivate(timer);
2186 * Mark it as ENQUEUED not INACTIVE otherwise the
2187 * timer could be seen as !active and just vanish away
2188 * under us on another CPU
2190 __remove_hrtimer(timer, old_base, HRTIMER_STATE_ENQUEUED, 0);
2191 timer->base = new_base;
2193 * Enqueue the timers on the new cpu. This does not
2194 * reprogram the event device in case the timer
2195 * expires before the earliest on this CPU, but we run
2196 * hrtimer_interrupt after we migrated everything to
2197 * sort out already expired timers and reprogram the
2200 enqueue_hrtimer(timer, new_base, HRTIMER_MODE_ABS);
2204 int hrtimers_cpu_dying(unsigned int dying_cpu)
2206 int i, ncpu = cpumask_any_and(cpu_active_mask, housekeeping_cpumask(HK_TYPE_TIMER));
2207 struct hrtimer_cpu_base *old_base, *new_base;
2209 old_base = this_cpu_ptr(&hrtimer_bases);
2210 new_base = &per_cpu(hrtimer_bases, ncpu);
2213 * The caller is globally serialized and nobody else
2214 * takes two locks at once, deadlock is not possible.
2216 raw_spin_lock(&old_base->lock);
2217 raw_spin_lock_nested(&new_base->lock, SINGLE_DEPTH_NESTING);
2219 for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
2220 migrate_hrtimer_list(&old_base->clock_base[i],
2221 &new_base->clock_base[i]);
2225 * The migration might have changed the first expiring softirq
2226 * timer on this CPU. Update it.
2228 __hrtimer_get_next_event(new_base, HRTIMER_ACTIVE_SOFT);
2229 /* Tell the other CPU to retrigger the next event */
2230 smp_call_function_single(ncpu, retrigger_next_event, NULL, 0);
2232 raw_spin_unlock(&new_base->lock);
2233 old_base->online = 0;
2234 raw_spin_unlock(&old_base->lock);
2239 #endif /* CONFIG_HOTPLUG_CPU */
2241 void __init hrtimers_init(void)
2243 hrtimers_prepare_cpu(smp_processor_id());
2244 open_softirq(HRTIMER_SOFTIRQ, hrtimer_run_softirq);
2248 * schedule_hrtimeout_range_clock - sleep until timeout
2249 * @expires: timeout value (ktime_t)
2250 * @delta: slack in expires timeout (ktime_t) for SCHED_OTHER tasks
2252 * @clock_id: timer clock to be used
2255 schedule_hrtimeout_range_clock(ktime_t *expires, u64 delta,
2256 const enum hrtimer_mode mode, clockid_t clock_id)
2258 struct hrtimer_sleeper t;
2261 * Optimize when a zero timeout value is given. It does not
2262 * matter whether this is an absolute or a relative time.
2264 if (expires && *expires == 0) {
2265 __set_current_state(TASK_RUNNING);
2270 * A NULL parameter means "infinite"
2278 * Override any slack passed by the user if under
2281 if (rt_task(current))
2284 hrtimer_init_sleeper_on_stack(&t, clock_id, mode);
2285 hrtimer_set_expires_range_ns(&t.timer, *expires, delta);
2286 hrtimer_sleeper_start_expires(&t, mode);
2291 hrtimer_cancel(&t.timer);
2292 destroy_hrtimer_on_stack(&t.timer);
2294 __set_current_state(TASK_RUNNING);
2296 return !t.task ? 0 : -EINTR;
2298 EXPORT_SYMBOL_GPL(schedule_hrtimeout_range_clock);
2301 * schedule_hrtimeout_range - sleep until timeout
2302 * @expires: timeout value (ktime_t)
2303 * @delta: slack in expires timeout (ktime_t) for SCHED_OTHER tasks
2306 * Make the current task sleep until the given expiry time has
2307 * elapsed. The routine will return immediately unless
2308 * the current task state has been set (see set_current_state()).
2310 * The @delta argument gives the kernel the freedom to schedule the
2311 * actual wakeup to a time that is both power and performance friendly
2312 * for regular (non RT/DL) tasks.
2313 * The kernel give the normal best effort behavior for "@expires+@delta",
2314 * but may decide to fire the timer earlier, but no earlier than @expires.
2316 * You can set the task state as follows -
2318 * %TASK_UNINTERRUPTIBLE - at least @timeout time is guaranteed to
2319 * pass before the routine returns unless the current task is explicitly
2320 * woken up, (e.g. by wake_up_process()).
2322 * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
2323 * delivered to the current task or the current task is explicitly woken
2326 * The current task state is guaranteed to be TASK_RUNNING when this
2329 * Returns 0 when the timer has expired. If the task was woken before the
2330 * timer expired by a signal (only possible in state TASK_INTERRUPTIBLE) or
2331 * by an explicit wakeup, it returns -EINTR.
2333 int __sched schedule_hrtimeout_range(ktime_t *expires, u64 delta,
2334 const enum hrtimer_mode mode)
2336 return schedule_hrtimeout_range_clock(expires, delta, mode,
2339 EXPORT_SYMBOL_GPL(schedule_hrtimeout_range);
2342 * schedule_hrtimeout - sleep until timeout
2343 * @expires: timeout value (ktime_t)
2346 * Make the current task sleep until the given expiry time has
2347 * elapsed. The routine will return immediately unless
2348 * the current task state has been set (see set_current_state()).
2350 * You can set the task state as follows -
2352 * %TASK_UNINTERRUPTIBLE - at least @timeout time is guaranteed to
2353 * pass before the routine returns unless the current task is explicitly
2354 * woken up, (e.g. by wake_up_process()).
2356 * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
2357 * delivered to the current task or the current task is explicitly woken
2360 * The current task state is guaranteed to be TASK_RUNNING when this
2363 * Returns 0 when the timer has expired. If the task was woken before the
2364 * timer expired by a signal (only possible in state TASK_INTERRUPTIBLE) or
2365 * by an explicit wakeup, it returns -EINTR.
2367 int __sched schedule_hrtimeout(ktime_t *expires,
2368 const enum hrtimer_mode mode)
2370 return schedule_hrtimeout_range(expires, 0, mode);
2372 EXPORT_SYMBOL_GPL(schedule_hrtimeout);