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.h>
47 #include <linux/sched/sysctl.h>
48 #include <linux/sched/rt.h>
49 #include <linux/sched/deadline.h>
50 #include <linux/timer.h>
51 #include <linux/freezer.h>
53 #include <asm/uaccess.h>
55 #include <trace/events/timer.h>
57 #include "tick-internal.h"
62 * There are more clockids then hrtimer bases. Thus, we index
63 * into the timer bases by the hrtimer_base_type enum. When trying
64 * to reach a base using a clockid, hrtimer_clockid_to_base()
65 * is used to convert from clockid to the proper hrtimer_base_type.
67 DEFINE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases) =
70 .lock = __RAW_SPIN_LOCK_UNLOCKED(hrtimer_bases.lock),
74 .index = HRTIMER_BASE_MONOTONIC,
75 .clockid = CLOCK_MONOTONIC,
76 .get_time = &ktime_get,
77 .resolution = KTIME_LOW_RES,
80 .index = HRTIMER_BASE_REALTIME,
81 .clockid = CLOCK_REALTIME,
82 .get_time = &ktime_get_real,
83 .resolution = KTIME_LOW_RES,
86 .index = HRTIMER_BASE_BOOTTIME,
87 .clockid = CLOCK_BOOTTIME,
88 .get_time = &ktime_get_boottime,
89 .resolution = KTIME_LOW_RES,
92 .index = HRTIMER_BASE_TAI,
94 .get_time = &ktime_get_clocktai,
95 .resolution = KTIME_LOW_RES,
100 static const int hrtimer_clock_to_base_table[MAX_CLOCKS] = {
101 [CLOCK_REALTIME] = HRTIMER_BASE_REALTIME,
102 [CLOCK_MONOTONIC] = HRTIMER_BASE_MONOTONIC,
103 [CLOCK_BOOTTIME] = HRTIMER_BASE_BOOTTIME,
104 [CLOCK_TAI] = HRTIMER_BASE_TAI,
107 static inline int hrtimer_clockid_to_base(clockid_t clock_id)
109 return hrtimer_clock_to_base_table[clock_id];
114 * Get the coarse grained time at the softirq based on xtime and
117 static void hrtimer_get_softirq_time(struct hrtimer_cpu_base *base)
119 ktime_t xtim, mono, boot, tai;
120 ktime_t off_real, off_boot, off_tai;
122 mono = ktime_get_update_offsets_tick(&off_real, &off_boot, &off_tai);
123 boot = ktime_add(mono, off_boot);
124 xtim = ktime_add(mono, off_real);
125 tai = ktime_add(mono, off_tai);
127 base->clock_base[HRTIMER_BASE_REALTIME].softirq_time = xtim;
128 base->clock_base[HRTIMER_BASE_MONOTONIC].softirq_time = mono;
129 base->clock_base[HRTIMER_BASE_BOOTTIME].softirq_time = boot;
130 base->clock_base[HRTIMER_BASE_TAI].softirq_time = tai;
134 * Functions and macros which are different for UP/SMP systems are kept in a
140 * We are using hashed locking: holding per_cpu(hrtimer_bases)[n].lock
141 * means that all timers which are tied to this base via timer->base are
142 * locked, and the base itself is locked too.
144 * So __run_timers/migrate_timers can safely modify all timers which could
145 * be found on the lists/queues.
147 * When the timer's base is locked, and the timer removed from list, it is
148 * possible to set timer->base = NULL and drop the lock: the timer remains
152 struct hrtimer_clock_base *lock_hrtimer_base(const struct hrtimer *timer,
153 unsigned long *flags)
155 struct hrtimer_clock_base *base;
159 if (likely(base != NULL)) {
160 raw_spin_lock_irqsave(&base->cpu_base->lock, *flags);
161 if (likely(base == timer->base))
163 /* The timer has migrated to another CPU: */
164 raw_spin_unlock_irqrestore(&base->cpu_base->lock, *flags);
171 * With HIGHRES=y we do not migrate the timer when it is expiring
172 * before the next event on the target cpu because we cannot reprogram
173 * the target cpu hardware and we would cause it to fire late.
175 * Called with cpu_base->lock of target cpu held.
178 hrtimer_check_target(struct hrtimer *timer, struct hrtimer_clock_base *new_base)
180 #ifdef CONFIG_HIGH_RES_TIMERS
183 if (!new_base->cpu_base->hres_active)
186 expires = ktime_sub(hrtimer_get_expires(timer), new_base->offset);
187 return expires.tv64 <= new_base->cpu_base->expires_next.tv64;
194 * Switch the timer base to the current CPU when possible.
196 static inline struct hrtimer_clock_base *
197 switch_hrtimer_base(struct hrtimer *timer, struct hrtimer_clock_base *base,
200 struct hrtimer_clock_base *new_base;
201 struct hrtimer_cpu_base *new_cpu_base;
202 int this_cpu = smp_processor_id();
203 int cpu = get_nohz_timer_target(pinned);
204 int basenum = base->index;
207 new_cpu_base = &per_cpu(hrtimer_bases, cpu);
208 new_base = &new_cpu_base->clock_base[basenum];
210 if (base != new_base) {
212 * We are trying to move timer to new_base.
213 * However we can't change timer's base while it is running,
214 * so we keep it on the same CPU. No hassle vs. reprogramming
215 * the event source in the high resolution case. The softirq
216 * code will take care of this when the timer function has
217 * completed. There is no conflict as we hold the lock until
218 * the timer is enqueued.
220 if (unlikely(hrtimer_callback_running(timer)))
223 /* See the comment in lock_timer_base() */
225 raw_spin_unlock(&base->cpu_base->lock);
226 raw_spin_lock(&new_base->cpu_base->lock);
228 if (cpu != this_cpu && hrtimer_check_target(timer, new_base)) {
230 raw_spin_unlock(&new_base->cpu_base->lock);
231 raw_spin_lock(&base->cpu_base->lock);
235 timer->base = new_base;
237 if (cpu != this_cpu && hrtimer_check_target(timer, new_base)) {
245 #else /* CONFIG_SMP */
247 static inline struct hrtimer_clock_base *
248 lock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
250 struct hrtimer_clock_base *base = timer->base;
252 raw_spin_lock_irqsave(&base->cpu_base->lock, *flags);
257 # define switch_hrtimer_base(t, b, p) (b)
259 #endif /* !CONFIG_SMP */
262 * Functions for the union type storage format of ktime_t which are
263 * too large for inlining:
265 #if BITS_PER_LONG < 64
267 * Divide a ktime value by a nanosecond value
269 s64 __ktime_divns(const ktime_t kt, s64 div)
275 dclc = ktime_to_ns(kt);
276 tmp = dclc < 0 ? -dclc : dclc;
278 /* Make sure the divisor is less than 2^32: */
284 do_div(tmp, (unsigned long) div);
285 return dclc < 0 ? -tmp : tmp;
287 EXPORT_SYMBOL_GPL(__ktime_divns);
288 #endif /* BITS_PER_LONG >= 64 */
291 * Add two ktime values and do a safety check for overflow:
293 ktime_t ktime_add_safe(const ktime_t lhs, const ktime_t rhs)
295 ktime_t res = ktime_add(lhs, rhs);
298 * We use KTIME_SEC_MAX here, the maximum timeout which we can
299 * return to user space in a timespec:
301 if (res.tv64 < 0 || res.tv64 < lhs.tv64 || res.tv64 < rhs.tv64)
302 res = ktime_set(KTIME_SEC_MAX, 0);
307 EXPORT_SYMBOL_GPL(ktime_add_safe);
309 #ifdef CONFIG_DEBUG_OBJECTS_TIMERS
311 static struct debug_obj_descr hrtimer_debug_descr;
313 static void *hrtimer_debug_hint(void *addr)
315 return ((struct hrtimer *) addr)->function;
319 * fixup_init is called when:
320 * - an active object is initialized
322 static int hrtimer_fixup_init(void *addr, enum debug_obj_state state)
324 struct hrtimer *timer = addr;
327 case ODEBUG_STATE_ACTIVE:
328 hrtimer_cancel(timer);
329 debug_object_init(timer, &hrtimer_debug_descr);
337 * fixup_activate is called when:
338 * - an active object is activated
339 * - an unknown object is activated (might be a statically initialized object)
341 static int hrtimer_fixup_activate(void *addr, enum debug_obj_state state)
345 case ODEBUG_STATE_NOTAVAILABLE:
349 case ODEBUG_STATE_ACTIVE:
358 * fixup_free is called when:
359 * - an active object is freed
361 static int hrtimer_fixup_free(void *addr, enum debug_obj_state state)
363 struct hrtimer *timer = addr;
366 case ODEBUG_STATE_ACTIVE:
367 hrtimer_cancel(timer);
368 debug_object_free(timer, &hrtimer_debug_descr);
375 static struct debug_obj_descr hrtimer_debug_descr = {
377 .debug_hint = hrtimer_debug_hint,
378 .fixup_init = hrtimer_fixup_init,
379 .fixup_activate = hrtimer_fixup_activate,
380 .fixup_free = hrtimer_fixup_free,
383 static inline void debug_hrtimer_init(struct hrtimer *timer)
385 debug_object_init(timer, &hrtimer_debug_descr);
388 static inline void debug_hrtimer_activate(struct hrtimer *timer)
390 debug_object_activate(timer, &hrtimer_debug_descr);
393 static inline void debug_hrtimer_deactivate(struct hrtimer *timer)
395 debug_object_deactivate(timer, &hrtimer_debug_descr);
398 static inline void debug_hrtimer_free(struct hrtimer *timer)
400 debug_object_free(timer, &hrtimer_debug_descr);
403 static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
404 enum hrtimer_mode mode);
406 void hrtimer_init_on_stack(struct hrtimer *timer, clockid_t clock_id,
407 enum hrtimer_mode mode)
409 debug_object_init_on_stack(timer, &hrtimer_debug_descr);
410 __hrtimer_init(timer, clock_id, mode);
412 EXPORT_SYMBOL_GPL(hrtimer_init_on_stack);
414 void destroy_hrtimer_on_stack(struct hrtimer *timer)
416 debug_object_free(timer, &hrtimer_debug_descr);
420 static inline void debug_hrtimer_init(struct hrtimer *timer) { }
421 static inline void debug_hrtimer_activate(struct hrtimer *timer) { }
422 static inline void debug_hrtimer_deactivate(struct hrtimer *timer) { }
426 debug_init(struct hrtimer *timer, clockid_t clockid,
427 enum hrtimer_mode mode)
429 debug_hrtimer_init(timer);
430 trace_hrtimer_init(timer, clockid, mode);
433 static inline void debug_activate(struct hrtimer *timer)
435 debug_hrtimer_activate(timer);
436 trace_hrtimer_start(timer);
439 static inline void debug_deactivate(struct hrtimer *timer)
441 debug_hrtimer_deactivate(timer);
442 trace_hrtimer_cancel(timer);
445 #if defined(CONFIG_NO_HZ_COMMON) || defined(CONFIG_HIGH_RES_TIMERS)
446 static ktime_t __hrtimer_get_next_event(struct hrtimer_cpu_base *cpu_base)
448 struct hrtimer_clock_base *base = cpu_base->clock_base;
449 ktime_t expires, expires_next = { .tv64 = KTIME_MAX };
452 for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++, base++) {
453 struct timerqueue_node *next;
454 struct hrtimer *timer;
456 next = timerqueue_getnext(&base->active);
460 timer = container_of(next, struct hrtimer, node);
461 expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
462 if (expires.tv64 < expires_next.tv64)
463 expires_next = expires;
466 * clock_was_set() might have changed base->offset of any of
467 * the clock bases so the result might be negative. Fix it up
468 * to prevent a false positive in clockevents_program_event().
470 if (expires_next.tv64 < 0)
471 expires_next.tv64 = 0;
476 /* High resolution timer related functions */
477 #ifdef CONFIG_HIGH_RES_TIMERS
480 * High resolution timer enabled ?
482 static int hrtimer_hres_enabled __read_mostly = 1;
485 * Enable / Disable high resolution mode
487 static int __init setup_hrtimer_hres(char *str)
489 if (!strcmp(str, "off"))
490 hrtimer_hres_enabled = 0;
491 else if (!strcmp(str, "on"))
492 hrtimer_hres_enabled = 1;
498 __setup("highres=", setup_hrtimer_hres);
501 * hrtimer_high_res_enabled - query, if the highres mode is enabled
503 static inline int hrtimer_is_hres_enabled(void)
505 return hrtimer_hres_enabled;
509 * Is the high resolution mode active ?
511 static inline int hrtimer_hres_active(void)
513 return __this_cpu_read(hrtimer_bases.hres_active);
517 * Reprogram the event source with checking both queues for the
519 * Called with interrupts disabled and base->lock held
522 hrtimer_force_reprogram(struct hrtimer_cpu_base *cpu_base, int skip_equal)
524 ktime_t expires_next = __hrtimer_get_next_event(cpu_base);
526 if (skip_equal && expires_next.tv64 == cpu_base->expires_next.tv64)
529 cpu_base->expires_next.tv64 = expires_next.tv64;
532 * If a hang was detected in the last timer interrupt then we
533 * leave the hang delay active in the hardware. We want the
534 * system to make progress. That also prevents the following
536 * T1 expires 50ms from now
537 * T2 expires 5s from now
539 * T1 is removed, so this code is called and would reprogram
540 * the hardware to 5s from now. Any hrtimer_start after that
541 * will not reprogram the hardware due to hang_detected being
542 * set. So we'd effectivly block all timers until the T2 event
545 if (cpu_base->hang_detected)
548 if (cpu_base->expires_next.tv64 != KTIME_MAX)
549 tick_program_event(cpu_base->expires_next, 1);
553 * Shared reprogramming for clock_realtime and clock_monotonic
555 * When a timer is enqueued and expires earlier than the already enqueued
556 * timers, we have to check, whether it expires earlier than the timer for
557 * which the clock event device was armed.
559 * Note, that in case the state has HRTIMER_STATE_CALLBACK set, no reprogramming
560 * and no expiry check happens. The timer gets enqueued into the rbtree. The
561 * reprogramming and expiry check is done in the hrtimer_interrupt or in the
564 * Called with interrupts disabled and base->cpu_base.lock held
566 static int hrtimer_reprogram(struct hrtimer *timer,
567 struct hrtimer_clock_base *base)
569 struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
570 ktime_t expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
573 WARN_ON_ONCE(hrtimer_get_expires_tv64(timer) < 0);
576 * When the callback is running, we do not reprogram the clock event
577 * device. The timer callback is either running on a different CPU or
578 * the callback is executed in the hrtimer_interrupt context. The
579 * reprogramming is handled either by the softirq, which called the
580 * callback or at the end of the hrtimer_interrupt.
582 if (hrtimer_callback_running(timer))
586 * CLOCK_REALTIME timer might be requested with an absolute
587 * expiry time which is less than base->offset. Nothing wrong
588 * about that, just avoid to call into the tick code, which
589 * has now objections against negative expiry values.
591 if (expires.tv64 < 0)
594 if (expires.tv64 >= cpu_base->expires_next.tv64)
598 * When the target cpu of the timer is currently executing
599 * hrtimer_interrupt(), then we do not touch the clock event
600 * device. hrtimer_interrupt() will reevaluate all clock bases
601 * before reprogramming the device.
603 if (cpu_base->in_hrtirq)
607 * If a hang was detected in the last timer interrupt then we
608 * do not schedule a timer which is earlier than the expiry
609 * which we enforced in the hang detection. We want the system
612 if (cpu_base->hang_detected)
616 * Clockevents returns -ETIME, when the event was in the past.
618 res = tick_program_event(expires, 0);
619 if (!IS_ERR_VALUE(res))
620 cpu_base->expires_next = expires;
625 * Initialize the high resolution related parts of cpu_base
627 static inline void hrtimer_init_hres(struct hrtimer_cpu_base *base)
629 base->expires_next.tv64 = KTIME_MAX;
630 base->hres_active = 0;
633 static inline ktime_t hrtimer_update_base(struct hrtimer_cpu_base *base)
635 ktime_t *offs_real = &base->clock_base[HRTIMER_BASE_REALTIME].offset;
636 ktime_t *offs_boot = &base->clock_base[HRTIMER_BASE_BOOTTIME].offset;
637 ktime_t *offs_tai = &base->clock_base[HRTIMER_BASE_TAI].offset;
639 return ktime_get_update_offsets_now(offs_real, offs_boot, offs_tai);
643 * Retrigger next event is called after clock was set
645 * Called with interrupts disabled via on_each_cpu()
647 static void retrigger_next_event(void *arg)
649 struct hrtimer_cpu_base *base = this_cpu_ptr(&hrtimer_bases);
651 if (!hrtimer_hres_active())
654 raw_spin_lock(&base->lock);
655 hrtimer_update_base(base);
656 hrtimer_force_reprogram(base, 0);
657 raw_spin_unlock(&base->lock);
661 * Switch to high resolution mode
663 static int hrtimer_switch_to_hres(void)
665 int i, cpu = smp_processor_id();
666 struct hrtimer_cpu_base *base = &per_cpu(hrtimer_bases, cpu);
669 if (base->hres_active)
672 local_irq_save(flags);
674 if (tick_init_highres()) {
675 local_irq_restore(flags);
676 printk(KERN_WARNING "Could not switch to high resolution "
677 "mode on CPU %d\n", cpu);
680 base->hres_active = 1;
681 for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++)
682 base->clock_base[i].resolution = KTIME_HIGH_RES;
684 tick_setup_sched_timer();
685 /* "Retrigger" the interrupt to get things going */
686 retrigger_next_event(NULL);
687 local_irq_restore(flags);
691 static void clock_was_set_work(struct work_struct *work)
696 static DECLARE_WORK(hrtimer_work, clock_was_set_work);
699 * Called from timekeeping and resume code to reprogramm the hrtimer
700 * interrupt device on all cpus.
702 void clock_was_set_delayed(void)
704 schedule_work(&hrtimer_work);
709 static inline int hrtimer_hres_active(void) { return 0; }
710 static inline int hrtimer_is_hres_enabled(void) { return 0; }
711 static inline int hrtimer_switch_to_hres(void) { return 0; }
713 hrtimer_force_reprogram(struct hrtimer_cpu_base *base, int skip_equal) { }
714 static inline int hrtimer_reprogram(struct hrtimer *timer,
715 struct hrtimer_clock_base *base)
719 static inline void hrtimer_init_hres(struct hrtimer_cpu_base *base) { }
720 static inline void retrigger_next_event(void *arg) { }
722 #endif /* CONFIG_HIGH_RES_TIMERS */
725 * Clock realtime was set
727 * Change the offset of the realtime clock vs. the monotonic
730 * We might have to reprogram the high resolution timer interrupt. On
731 * SMP we call the architecture specific code to retrigger _all_ high
732 * resolution timer interrupts. On UP we just disable interrupts and
733 * call the high resolution interrupt code.
735 void clock_was_set(void)
737 #ifdef CONFIG_HIGH_RES_TIMERS
738 /* Retrigger the CPU local events everywhere */
739 on_each_cpu(retrigger_next_event, NULL, 1);
741 timerfd_clock_was_set();
745 * During resume we might have to reprogram the high resolution timer
746 * interrupt on all online CPUs. However, all other CPUs will be
747 * stopped with IRQs interrupts disabled so the clock_was_set() call
750 void hrtimers_resume(void)
752 WARN_ONCE(!irqs_disabled(),
753 KERN_INFO "hrtimers_resume() called with IRQs enabled!");
755 /* Retrigger on the local CPU */
756 retrigger_next_event(NULL);
757 /* And schedule a retrigger for all others */
758 clock_was_set_delayed();
761 static inline void timer_stats_hrtimer_set_start_info(struct hrtimer *timer)
763 #ifdef CONFIG_TIMER_STATS
764 if (timer->start_site)
766 timer->start_site = __builtin_return_address(0);
767 memcpy(timer->start_comm, current->comm, TASK_COMM_LEN);
768 timer->start_pid = current->pid;
772 static inline void timer_stats_hrtimer_clear_start_info(struct hrtimer *timer)
774 #ifdef CONFIG_TIMER_STATS
775 timer->start_site = NULL;
779 static inline void timer_stats_account_hrtimer(struct hrtimer *timer)
781 #ifdef CONFIG_TIMER_STATS
782 if (likely(!timer_stats_active))
784 timer_stats_update_stats(timer, timer->start_pid, timer->start_site,
785 timer->function, timer->start_comm, 0);
790 * Counterpart to lock_hrtimer_base above:
793 void unlock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
795 raw_spin_unlock_irqrestore(&timer->base->cpu_base->lock, *flags);
799 * hrtimer_forward - forward the timer expiry
800 * @timer: hrtimer to forward
801 * @now: forward past this time
802 * @interval: the interval to forward
804 * Forward the timer expiry so it will expire in the future.
805 * Returns the number of overruns.
807 u64 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval)
812 delta = ktime_sub(now, hrtimer_get_expires(timer));
817 if (interval.tv64 < timer->base->resolution.tv64)
818 interval.tv64 = timer->base->resolution.tv64;
820 if (unlikely(delta.tv64 >= interval.tv64)) {
821 s64 incr = ktime_to_ns(interval);
823 orun = ktime_divns(delta, incr);
824 hrtimer_add_expires_ns(timer, incr * orun);
825 if (hrtimer_get_expires_tv64(timer) > now.tv64)
828 * This (and the ktime_add() below) is the
829 * correction for exact:
833 hrtimer_add_expires(timer, interval);
837 EXPORT_SYMBOL_GPL(hrtimer_forward);
840 * enqueue_hrtimer - internal function to (re)start a timer
842 * The timer is inserted in expiry order. Insertion into the
843 * red black tree is O(log(n)). Must hold the base lock.
845 * Returns 1 when the new timer is the leftmost timer in the tree.
847 static int enqueue_hrtimer(struct hrtimer *timer,
848 struct hrtimer_clock_base *base)
850 debug_activate(timer);
852 timerqueue_add(&base->active, &timer->node);
853 base->cpu_base->active_bases |= 1 << base->index;
856 * HRTIMER_STATE_ENQUEUED is or'ed to the current state to preserve the
857 * state of a possibly running callback.
859 timer->state |= HRTIMER_STATE_ENQUEUED;
861 return (&timer->node == base->active.next);
865 * __remove_hrtimer - internal function to remove a timer
867 * Caller must hold the base lock.
869 * High resolution timer mode reprograms the clock event device when the
870 * timer is the one which expires next. The caller can disable this by setting
871 * reprogram to zero. This is useful, when the context does a reprogramming
872 * anyway (e.g. timer interrupt)
874 static void __remove_hrtimer(struct hrtimer *timer,
875 struct hrtimer_clock_base *base,
876 unsigned long newstate, int reprogram)
878 struct timerqueue_node *next_timer;
879 if (!(timer->state & HRTIMER_STATE_ENQUEUED))
882 next_timer = timerqueue_getnext(&base->active);
883 timerqueue_del(&base->active, &timer->node);
884 if (&timer->node == next_timer) {
885 #ifdef CONFIG_HIGH_RES_TIMERS
886 /* Reprogram the clock event device. if enabled */
887 if (reprogram && hrtimer_hres_active()) {
890 expires = ktime_sub(hrtimer_get_expires(timer),
892 if (base->cpu_base->expires_next.tv64 == expires.tv64)
893 hrtimer_force_reprogram(base->cpu_base, 1);
897 if (!timerqueue_getnext(&base->active))
898 base->cpu_base->active_bases &= ~(1 << base->index);
900 timer->state = newstate;
904 * remove hrtimer, called with base lock held
907 remove_hrtimer(struct hrtimer *timer, struct hrtimer_clock_base *base)
909 if (hrtimer_is_queued(timer)) {
914 * Remove the timer and force reprogramming when high
915 * resolution mode is active and the timer is on the current
916 * CPU. If we remove a timer on another CPU, reprogramming is
917 * skipped. The interrupt event on this CPU is fired and
918 * reprogramming happens in the interrupt handler. This is a
919 * rare case and less expensive than a smp call.
921 debug_deactivate(timer);
922 timer_stats_hrtimer_clear_start_info(timer);
923 reprogram = base->cpu_base == this_cpu_ptr(&hrtimer_bases);
925 * We must preserve the CALLBACK state flag here,
926 * otherwise we could move the timer base in
927 * switch_hrtimer_base.
929 state = timer->state & HRTIMER_STATE_CALLBACK;
930 __remove_hrtimer(timer, base, state, reprogram);
936 int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
937 unsigned long delta_ns, const enum hrtimer_mode mode,
940 struct hrtimer_clock_base *base, *new_base;
944 base = lock_hrtimer_base(timer, &flags);
946 /* Remove an active timer from the queue: */
947 ret = remove_hrtimer(timer, base);
949 if (mode & HRTIMER_MODE_REL) {
950 tim = ktime_add_safe(tim, base->get_time());
952 * CONFIG_TIME_LOW_RES is a temporary way for architectures
953 * to signal that they simply return xtime in
954 * do_gettimeoffset(). In this case we want to round up by
955 * resolution when starting a relative timer, to avoid short
956 * timeouts. This will go away with the GTOD framework.
958 #ifdef CONFIG_TIME_LOW_RES
959 tim = ktime_add_safe(tim, base->resolution);
963 hrtimer_set_expires_range_ns(timer, tim, delta_ns);
965 /* Switch the timer base, if necessary: */
966 new_base = switch_hrtimer_base(timer, base, mode & HRTIMER_MODE_PINNED);
968 timer_stats_hrtimer_set_start_info(timer);
970 leftmost = enqueue_hrtimer(timer, new_base);
973 unlock_hrtimer_base(timer, &flags);
977 if (!hrtimer_is_hres_active(timer)) {
979 * Kick to reschedule the next tick to handle the new timer
980 * on dynticks target.
982 wake_up_nohz_cpu(new_base->cpu_base->cpu);
983 } else if (new_base->cpu_base == this_cpu_ptr(&hrtimer_bases) &&
984 hrtimer_reprogram(timer, new_base)) {
986 * Only allow reprogramming if the new base is on this CPU.
987 * (it might still be on another CPU if the timer was pending)
989 * XXX send_remote_softirq() ?
993 * We need to drop cpu_base->lock to avoid a
994 * lock ordering issue vs. rq->lock.
996 raw_spin_unlock(&new_base->cpu_base->lock);
997 raise_softirq_irqoff(HRTIMER_SOFTIRQ);
998 local_irq_restore(flags);
1001 __raise_softirq_irqoff(HRTIMER_SOFTIRQ);
1005 unlock_hrtimer_base(timer, &flags);
1009 EXPORT_SYMBOL_GPL(__hrtimer_start_range_ns);
1012 * hrtimer_start_range_ns - (re)start an hrtimer on the current CPU
1013 * @timer: the timer to be added
1015 * @delta_ns: "slack" range for the timer
1016 * @mode: expiry mode: absolute (HRTIMER_MODE_ABS) or
1017 * relative (HRTIMER_MODE_REL)
1021 * 1 when the timer was active
1023 int hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
1024 unsigned long delta_ns, const enum hrtimer_mode mode)
1026 return __hrtimer_start_range_ns(timer, tim, delta_ns, mode, 1);
1028 EXPORT_SYMBOL_GPL(hrtimer_start_range_ns);
1031 * hrtimer_start - (re)start an hrtimer on the current CPU
1032 * @timer: the timer to be added
1034 * @mode: expiry mode: absolute (HRTIMER_MODE_ABS) or
1035 * relative (HRTIMER_MODE_REL)
1039 * 1 when the timer was active
1042 hrtimer_start(struct hrtimer *timer, ktime_t tim, const enum hrtimer_mode mode)
1044 return __hrtimer_start_range_ns(timer, tim, 0, mode, 1);
1046 EXPORT_SYMBOL_GPL(hrtimer_start);
1050 * hrtimer_try_to_cancel - try to deactivate a timer
1051 * @timer: hrtimer to stop
1054 * 0 when the timer was not active
1055 * 1 when the timer was active
1056 * -1 when the timer is currently excuting the callback function and
1059 int hrtimer_try_to_cancel(struct hrtimer *timer)
1061 struct hrtimer_clock_base *base;
1062 unsigned long flags;
1065 base = lock_hrtimer_base(timer, &flags);
1067 if (!hrtimer_callback_running(timer))
1068 ret = remove_hrtimer(timer, base);
1070 unlock_hrtimer_base(timer, &flags);
1075 EXPORT_SYMBOL_GPL(hrtimer_try_to_cancel);
1078 * hrtimer_cancel - cancel a timer and wait for the handler to finish.
1079 * @timer: the timer to be cancelled
1082 * 0 when the timer was not active
1083 * 1 when the timer was active
1085 int hrtimer_cancel(struct hrtimer *timer)
1088 int ret = hrtimer_try_to_cancel(timer);
1095 EXPORT_SYMBOL_GPL(hrtimer_cancel);
1098 * hrtimer_get_remaining - get remaining time for the timer
1099 * @timer: the timer to read
1101 ktime_t hrtimer_get_remaining(const struct hrtimer *timer)
1103 unsigned long flags;
1106 lock_hrtimer_base(timer, &flags);
1107 rem = hrtimer_expires_remaining(timer);
1108 unlock_hrtimer_base(timer, &flags);
1112 EXPORT_SYMBOL_GPL(hrtimer_get_remaining);
1114 #ifdef CONFIG_NO_HZ_COMMON
1116 * hrtimer_get_next_event - get the time until next expiry event
1118 * Returns the delta to the next expiry event or KTIME_MAX if no timer
1121 ktime_t hrtimer_get_next_event(void)
1123 struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1124 ktime_t mindelta = { .tv64 = KTIME_MAX };
1125 unsigned long flags;
1127 raw_spin_lock_irqsave(&cpu_base->lock, flags);
1129 if (!hrtimer_hres_active())
1130 mindelta = ktime_sub(__hrtimer_get_next_event(cpu_base),
1133 raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1135 if (mindelta.tv64 < 0)
1141 static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
1142 enum hrtimer_mode mode)
1144 struct hrtimer_cpu_base *cpu_base;
1147 memset(timer, 0, sizeof(struct hrtimer));
1149 cpu_base = raw_cpu_ptr(&hrtimer_bases);
1151 if (clock_id == CLOCK_REALTIME && mode != HRTIMER_MODE_ABS)
1152 clock_id = CLOCK_MONOTONIC;
1154 base = hrtimer_clockid_to_base(clock_id);
1155 timer->base = &cpu_base->clock_base[base];
1156 timerqueue_init(&timer->node);
1158 #ifdef CONFIG_TIMER_STATS
1159 timer->start_site = NULL;
1160 timer->start_pid = -1;
1161 memset(timer->start_comm, 0, TASK_COMM_LEN);
1166 * hrtimer_init - initialize a timer to the given clock
1167 * @timer: the timer to be initialized
1168 * @clock_id: the clock to be used
1169 * @mode: timer mode abs/rel
1171 void hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
1172 enum hrtimer_mode mode)
1174 debug_init(timer, clock_id, mode);
1175 __hrtimer_init(timer, clock_id, mode);
1177 EXPORT_SYMBOL_GPL(hrtimer_init);
1180 * hrtimer_get_res - get the timer resolution for a clock
1181 * @which_clock: which clock to query
1182 * @tp: pointer to timespec variable to store the resolution
1184 * Store the resolution of the clock selected by @which_clock in the
1185 * variable pointed to by @tp.
1187 int hrtimer_get_res(const clockid_t which_clock, struct timespec *tp)
1189 struct hrtimer_cpu_base *cpu_base;
1190 int base = hrtimer_clockid_to_base(which_clock);
1192 cpu_base = raw_cpu_ptr(&hrtimer_bases);
1193 *tp = ktime_to_timespec(cpu_base->clock_base[base].resolution);
1197 EXPORT_SYMBOL_GPL(hrtimer_get_res);
1199 static void __run_hrtimer(struct hrtimer *timer, ktime_t *now)
1201 struct hrtimer_clock_base *base = timer->base;
1202 struct hrtimer_cpu_base *cpu_base = base->cpu_base;
1203 enum hrtimer_restart (*fn)(struct hrtimer *);
1206 WARN_ON(!irqs_disabled());
1208 debug_deactivate(timer);
1209 __remove_hrtimer(timer, base, HRTIMER_STATE_CALLBACK, 0);
1210 timer_stats_account_hrtimer(timer);
1211 fn = timer->function;
1214 * Because we run timers from hardirq context, there is no chance
1215 * they get migrated to another cpu, therefore its safe to unlock
1218 raw_spin_unlock(&cpu_base->lock);
1219 trace_hrtimer_expire_entry(timer, now);
1220 restart = fn(timer);
1221 trace_hrtimer_expire_exit(timer);
1222 raw_spin_lock(&cpu_base->lock);
1225 * Note: We clear the CALLBACK bit after enqueue_hrtimer and
1226 * we do not reprogramm the event hardware. Happens either in
1227 * hrtimer_start_range_ns() or in hrtimer_interrupt()
1229 if (restart != HRTIMER_NORESTART) {
1230 BUG_ON(timer->state != HRTIMER_STATE_CALLBACK);
1231 enqueue_hrtimer(timer, base);
1234 WARN_ON_ONCE(!(timer->state & HRTIMER_STATE_CALLBACK));
1236 timer->state &= ~HRTIMER_STATE_CALLBACK;
1239 #ifdef CONFIG_HIGH_RES_TIMERS
1242 * High resolution timer interrupt
1243 * Called with interrupts disabled
1245 void hrtimer_interrupt(struct clock_event_device *dev)
1247 struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1248 ktime_t expires_next, now, entry_time, delta;
1251 BUG_ON(!cpu_base->hres_active);
1252 cpu_base->nr_events++;
1253 dev->next_event.tv64 = KTIME_MAX;
1255 raw_spin_lock(&cpu_base->lock);
1256 entry_time = now = hrtimer_update_base(cpu_base);
1258 cpu_base->in_hrtirq = 1;
1260 * We set expires_next to KTIME_MAX here with cpu_base->lock
1261 * held to prevent that a timer is enqueued in our queue via
1262 * the migration code. This does not affect enqueueing of
1263 * timers which run their callback and need to be requeued on
1266 cpu_base->expires_next.tv64 = KTIME_MAX;
1268 for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
1269 struct hrtimer_clock_base *base;
1270 struct timerqueue_node *node;
1273 if (!(cpu_base->active_bases & (1 << i)))
1276 base = cpu_base->clock_base + i;
1277 basenow = ktime_add(now, base->offset);
1279 while ((node = timerqueue_getnext(&base->active))) {
1280 struct hrtimer *timer;
1282 timer = container_of(node, struct hrtimer, node);
1285 * The immediate goal for using the softexpires is
1286 * minimizing wakeups, not running timers at the
1287 * earliest interrupt after their soft expiration.
1288 * This allows us to avoid using a Priority Search
1289 * Tree, which can answer a stabbing querry for
1290 * overlapping intervals and instead use the simple
1291 * BST we already have.
1292 * We don't add extra wakeups by delaying timers that
1293 * are right-of a not yet expired timer, because that
1294 * timer will have to trigger a wakeup anyway.
1296 if (basenow.tv64 < hrtimer_get_softexpires_tv64(timer))
1299 __run_hrtimer(timer, &basenow);
1302 /* Reevaluate the clock bases for the next expiry */
1303 expires_next = __hrtimer_get_next_event(cpu_base);
1305 * Store the new expiry value so the migration code can verify
1308 cpu_base->expires_next = expires_next;
1309 cpu_base->in_hrtirq = 0;
1310 raw_spin_unlock(&cpu_base->lock);
1312 /* Reprogramming necessary ? */
1313 if (expires_next.tv64 == KTIME_MAX ||
1314 !tick_program_event(expires_next, 0)) {
1315 cpu_base->hang_detected = 0;
1320 * The next timer was already expired due to:
1322 * - long lasting callbacks
1323 * - being scheduled away when running in a VM
1325 * We need to prevent that we loop forever in the hrtimer
1326 * interrupt routine. We give it 3 attempts to avoid
1327 * overreacting on some spurious event.
1329 * Acquire base lock for updating the offsets and retrieving
1332 raw_spin_lock(&cpu_base->lock);
1333 now = hrtimer_update_base(cpu_base);
1334 cpu_base->nr_retries++;
1338 * Give the system a chance to do something else than looping
1339 * here. We stored the entry time, so we know exactly how long
1340 * we spent here. We schedule the next event this amount of
1343 cpu_base->nr_hangs++;
1344 cpu_base->hang_detected = 1;
1345 raw_spin_unlock(&cpu_base->lock);
1346 delta = ktime_sub(now, entry_time);
1347 if (delta.tv64 > cpu_base->max_hang_time.tv64)
1348 cpu_base->max_hang_time = delta;
1350 * Limit it to a sensible value as we enforce a longer
1351 * delay. Give the CPU at least 100ms to catch up.
1353 if (delta.tv64 > 100 * NSEC_PER_MSEC)
1354 expires_next = ktime_add_ns(now, 100 * NSEC_PER_MSEC);
1356 expires_next = ktime_add(now, delta);
1357 tick_program_event(expires_next, 1);
1358 printk_once(KERN_WARNING "hrtimer: interrupt took %llu ns\n",
1359 ktime_to_ns(delta));
1363 * local version of hrtimer_peek_ahead_timers() called with interrupts
1366 static void __hrtimer_peek_ahead_timers(void)
1368 struct tick_device *td;
1370 if (!hrtimer_hres_active())
1373 td = this_cpu_ptr(&tick_cpu_device);
1374 if (td && td->evtdev)
1375 hrtimer_interrupt(td->evtdev);
1379 * hrtimer_peek_ahead_timers -- run soft-expired timers now
1381 * hrtimer_peek_ahead_timers will peek at the timer queue of
1382 * the current cpu and check if there are any timers for which
1383 * the soft expires time has passed. If any such timers exist,
1384 * they are run immediately and then removed from the timer queue.
1387 void hrtimer_peek_ahead_timers(void)
1389 unsigned long flags;
1391 local_irq_save(flags);
1392 __hrtimer_peek_ahead_timers();
1393 local_irq_restore(flags);
1396 static void run_hrtimer_softirq(struct softirq_action *h)
1398 hrtimer_peek_ahead_timers();
1401 #else /* CONFIG_HIGH_RES_TIMERS */
1403 static inline void __hrtimer_peek_ahead_timers(void) { }
1405 #endif /* !CONFIG_HIGH_RES_TIMERS */
1408 * Called from timer softirq every jiffy, expire hrtimers:
1410 * For HRT its the fall back code to run the softirq in the timer
1411 * softirq context in case the hrtimer initialization failed or has
1412 * not been done yet.
1414 void hrtimer_run_pending(void)
1416 if (hrtimer_hres_active())
1420 * This _is_ ugly: We have to check in the softirq context,
1421 * whether we can switch to highres and / or nohz mode. The
1422 * clocksource switch happens in the timer interrupt with
1423 * xtime_lock held. Notification from there only sets the
1424 * check bit in the tick_oneshot code, otherwise we might
1425 * deadlock vs. xtime_lock.
1427 if (tick_check_oneshot_change(!hrtimer_is_hres_enabled()))
1428 hrtimer_switch_to_hres();
1432 * Called from hardirq context every jiffy
1434 void hrtimer_run_queues(void)
1436 struct timerqueue_node *node;
1437 struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1438 struct hrtimer_clock_base *base;
1439 int index, gettime = 1;
1441 if (hrtimer_hres_active())
1444 for (index = 0; index < HRTIMER_MAX_CLOCK_BASES; index++) {
1445 base = &cpu_base->clock_base[index];
1446 if (!timerqueue_getnext(&base->active))
1450 hrtimer_get_softirq_time(cpu_base);
1454 raw_spin_lock(&cpu_base->lock);
1456 while ((node = timerqueue_getnext(&base->active))) {
1457 struct hrtimer *timer;
1459 timer = container_of(node, struct hrtimer, node);
1460 if (base->softirq_time.tv64 <=
1461 hrtimer_get_expires_tv64(timer))
1464 __run_hrtimer(timer, &base->softirq_time);
1466 raw_spin_unlock(&cpu_base->lock);
1471 * Sleep related functions:
1473 static enum hrtimer_restart hrtimer_wakeup(struct hrtimer *timer)
1475 struct hrtimer_sleeper *t =
1476 container_of(timer, struct hrtimer_sleeper, timer);
1477 struct task_struct *task = t->task;
1481 wake_up_process(task);
1483 return HRTIMER_NORESTART;
1486 void hrtimer_init_sleeper(struct hrtimer_sleeper *sl, struct task_struct *task)
1488 sl->timer.function = hrtimer_wakeup;
1491 EXPORT_SYMBOL_GPL(hrtimer_init_sleeper);
1493 static int __sched do_nanosleep(struct hrtimer_sleeper *t, enum hrtimer_mode mode)
1495 hrtimer_init_sleeper(t, current);
1498 set_current_state(TASK_INTERRUPTIBLE);
1499 hrtimer_start_expires(&t->timer, mode);
1500 if (!hrtimer_active(&t->timer))
1503 if (likely(t->task))
1504 freezable_schedule();
1506 hrtimer_cancel(&t->timer);
1507 mode = HRTIMER_MODE_ABS;
1509 } while (t->task && !signal_pending(current));
1511 __set_current_state(TASK_RUNNING);
1513 return t->task == NULL;
1516 static int update_rmtp(struct hrtimer *timer, struct timespec __user *rmtp)
1518 struct timespec rmt;
1521 rem = hrtimer_expires_remaining(timer);
1524 rmt = ktime_to_timespec(rem);
1526 if (copy_to_user(rmtp, &rmt, sizeof(*rmtp)))
1532 long __sched hrtimer_nanosleep_restart(struct restart_block *restart)
1534 struct hrtimer_sleeper t;
1535 struct timespec __user *rmtp;
1538 hrtimer_init_on_stack(&t.timer, restart->nanosleep.clockid,
1540 hrtimer_set_expires_tv64(&t.timer, restart->nanosleep.expires);
1542 if (do_nanosleep(&t, HRTIMER_MODE_ABS))
1545 rmtp = restart->nanosleep.rmtp;
1547 ret = update_rmtp(&t.timer, rmtp);
1552 /* The other values in restart are already filled in */
1553 ret = -ERESTART_RESTARTBLOCK;
1555 destroy_hrtimer_on_stack(&t.timer);
1559 long hrtimer_nanosleep(struct timespec *rqtp, struct timespec __user *rmtp,
1560 const enum hrtimer_mode mode, const clockid_t clockid)
1562 struct restart_block *restart;
1563 struct hrtimer_sleeper t;
1565 unsigned long slack;
1567 slack = current->timer_slack_ns;
1568 if (dl_task(current) || rt_task(current))
1571 hrtimer_init_on_stack(&t.timer, clockid, mode);
1572 hrtimer_set_expires_range_ns(&t.timer, timespec_to_ktime(*rqtp), slack);
1573 if (do_nanosleep(&t, mode))
1576 /* Absolute timers do not update the rmtp value and restart: */
1577 if (mode == HRTIMER_MODE_ABS) {
1578 ret = -ERESTARTNOHAND;
1583 ret = update_rmtp(&t.timer, rmtp);
1588 restart = ¤t->restart_block;
1589 restart->fn = hrtimer_nanosleep_restart;
1590 restart->nanosleep.clockid = t.timer.base->clockid;
1591 restart->nanosleep.rmtp = rmtp;
1592 restart->nanosleep.expires = hrtimer_get_expires_tv64(&t.timer);
1594 ret = -ERESTART_RESTARTBLOCK;
1596 destroy_hrtimer_on_stack(&t.timer);
1600 SYSCALL_DEFINE2(nanosleep, struct timespec __user *, rqtp,
1601 struct timespec __user *, rmtp)
1605 if (copy_from_user(&tu, rqtp, sizeof(tu)))
1608 if (!timespec_valid(&tu))
1611 return hrtimer_nanosleep(&tu, rmtp, HRTIMER_MODE_REL, CLOCK_MONOTONIC);
1615 * Functions related to boot-time initialization:
1617 static void init_hrtimers_cpu(int cpu)
1619 struct hrtimer_cpu_base *cpu_base = &per_cpu(hrtimer_bases, cpu);
1622 for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
1623 cpu_base->clock_base[i].cpu_base = cpu_base;
1624 timerqueue_init_head(&cpu_base->clock_base[i].active);
1627 cpu_base->cpu = cpu;
1628 hrtimer_init_hres(cpu_base);
1631 #ifdef CONFIG_HOTPLUG_CPU
1633 static void migrate_hrtimer_list(struct hrtimer_clock_base *old_base,
1634 struct hrtimer_clock_base *new_base)
1636 struct hrtimer *timer;
1637 struct timerqueue_node *node;
1639 while ((node = timerqueue_getnext(&old_base->active))) {
1640 timer = container_of(node, struct hrtimer, node);
1641 BUG_ON(hrtimer_callback_running(timer));
1642 debug_deactivate(timer);
1645 * Mark it as STATE_MIGRATE not INACTIVE otherwise the
1646 * timer could be seen as !active and just vanish away
1647 * under us on another CPU
1649 __remove_hrtimer(timer, old_base, HRTIMER_STATE_MIGRATE, 0);
1650 timer->base = new_base;
1652 * Enqueue the timers on the new cpu. This does not
1653 * reprogram the event device in case the timer
1654 * expires before the earliest on this CPU, but we run
1655 * hrtimer_interrupt after we migrated everything to
1656 * sort out already expired timers and reprogram the
1659 enqueue_hrtimer(timer, new_base);
1661 /* Clear the migration state bit */
1662 timer->state &= ~HRTIMER_STATE_MIGRATE;
1666 static void migrate_hrtimers(int scpu)
1668 struct hrtimer_cpu_base *old_base, *new_base;
1671 BUG_ON(cpu_online(scpu));
1672 tick_cancel_sched_timer(scpu);
1674 local_irq_disable();
1675 old_base = &per_cpu(hrtimer_bases, scpu);
1676 new_base = this_cpu_ptr(&hrtimer_bases);
1678 * The caller is globally serialized and nobody else
1679 * takes two locks at once, deadlock is not possible.
1681 raw_spin_lock(&new_base->lock);
1682 raw_spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING);
1684 for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
1685 migrate_hrtimer_list(&old_base->clock_base[i],
1686 &new_base->clock_base[i]);
1689 raw_spin_unlock(&old_base->lock);
1690 raw_spin_unlock(&new_base->lock);
1692 /* Check, if we got expired work to do */
1693 __hrtimer_peek_ahead_timers();
1697 #endif /* CONFIG_HOTPLUG_CPU */
1699 static int hrtimer_cpu_notify(struct notifier_block *self,
1700 unsigned long action, void *hcpu)
1702 int scpu = (long)hcpu;
1706 case CPU_UP_PREPARE:
1707 case CPU_UP_PREPARE_FROZEN:
1708 init_hrtimers_cpu(scpu);
1711 #ifdef CONFIG_HOTPLUG_CPU
1713 case CPU_DEAD_FROZEN:
1714 migrate_hrtimers(scpu);
1725 static struct notifier_block hrtimers_nb = {
1726 .notifier_call = hrtimer_cpu_notify,
1729 void __init hrtimers_init(void)
1731 hrtimer_cpu_notify(&hrtimers_nb, (unsigned long)CPU_UP_PREPARE,
1732 (void *)(long)smp_processor_id());
1733 register_cpu_notifier(&hrtimers_nb);
1734 #ifdef CONFIG_HIGH_RES_TIMERS
1735 open_softirq(HRTIMER_SOFTIRQ, run_hrtimer_softirq);
1740 * schedule_hrtimeout_range_clock - sleep until timeout
1741 * @expires: timeout value (ktime_t)
1742 * @delta: slack in expires timeout (ktime_t)
1743 * @mode: timer mode, HRTIMER_MODE_ABS or HRTIMER_MODE_REL
1744 * @clock: timer clock, CLOCK_MONOTONIC or CLOCK_REALTIME
1747 schedule_hrtimeout_range_clock(ktime_t *expires, unsigned long delta,
1748 const enum hrtimer_mode mode, int clock)
1750 struct hrtimer_sleeper t;
1753 * Optimize when a zero timeout value is given. It does not
1754 * matter whether this is an absolute or a relative time.
1756 if (expires && !expires->tv64) {
1757 __set_current_state(TASK_RUNNING);
1762 * A NULL parameter means "infinite"
1769 hrtimer_init_on_stack(&t.timer, clock, mode);
1770 hrtimer_set_expires_range_ns(&t.timer, *expires, delta);
1772 hrtimer_init_sleeper(&t, current);
1774 hrtimer_start_expires(&t.timer, mode);
1775 if (!hrtimer_active(&t.timer))
1781 hrtimer_cancel(&t.timer);
1782 destroy_hrtimer_on_stack(&t.timer);
1784 __set_current_state(TASK_RUNNING);
1786 return !t.task ? 0 : -EINTR;
1790 * schedule_hrtimeout_range - sleep until timeout
1791 * @expires: timeout value (ktime_t)
1792 * @delta: slack in expires timeout (ktime_t)
1793 * @mode: timer mode, HRTIMER_MODE_ABS or HRTIMER_MODE_REL
1795 * Make the current task sleep until the given expiry time has
1796 * elapsed. The routine will return immediately unless
1797 * the current task state has been set (see set_current_state()).
1799 * The @delta argument gives the kernel the freedom to schedule the
1800 * actual wakeup to a time that is both power and performance friendly.
1801 * The kernel give the normal best effort behavior for "@expires+@delta",
1802 * but may decide to fire the timer earlier, but no earlier than @expires.
1804 * You can set the task state as follows -
1806 * %TASK_UNINTERRUPTIBLE - at least @timeout time is guaranteed to
1807 * pass before the routine returns.
1809 * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
1810 * delivered to the current task.
1812 * The current task state is guaranteed to be TASK_RUNNING when this
1815 * Returns 0 when the timer has expired otherwise -EINTR
1817 int __sched schedule_hrtimeout_range(ktime_t *expires, unsigned long delta,
1818 const enum hrtimer_mode mode)
1820 return schedule_hrtimeout_range_clock(expires, delta, mode,
1823 EXPORT_SYMBOL_GPL(schedule_hrtimeout_range);
1826 * schedule_hrtimeout - sleep until timeout
1827 * @expires: timeout value (ktime_t)
1828 * @mode: timer mode, HRTIMER_MODE_ABS or HRTIMER_MODE_REL
1830 * Make the current task sleep until the given expiry time has
1831 * elapsed. The routine will return immediately unless
1832 * the current task state has been set (see set_current_state()).
1834 * You can set the task state as follows -
1836 * %TASK_UNINTERRUPTIBLE - at least @timeout time is guaranteed to
1837 * pass before the routine returns.
1839 * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
1840 * delivered to the current task.
1842 * The current task state is guaranteed to be TASK_RUNNING when this
1845 * Returns 0 when the timer has expired otherwise -EINTR
1847 int __sched schedule_hrtimeout(ktime_t *expires,
1848 const enum hrtimer_mode mode)
1850 return schedule_hrtimeout_range(expires, 0, mode);
1852 EXPORT_SYMBOL_GPL(schedule_hrtimeout);