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/module.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/timer.h>
49 #include <asm/uaccess.h>
51 #include <trace/events/timer.h>
56 * Note: If we want to add new timer bases, we have to skip the two
57 * clock ids captured by the cpu-timers. We do this by holding empty
58 * entries rather than doing math adjustment of the clock ids.
59 * This ensures that we capture erroneous accesses to these clock ids
60 * rather than moving them into the range of valid clock id's.
62 DEFINE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases) =
68 .index = CLOCK_REALTIME,
69 .get_time = &ktime_get_real,
70 .resolution = KTIME_LOW_RES,
73 .index = CLOCK_MONOTONIC,
74 .get_time = &ktime_get,
75 .resolution = KTIME_LOW_RES,
81 * Get the coarse grained time at the softirq based on xtime and
84 static void hrtimer_get_softirq_time(struct hrtimer_cpu_base *base)
87 struct timespec xts, tom;
91 seq = read_seqbegin(&xtime_lock);
92 xts = current_kernel_time();
93 tom = wall_to_monotonic;
94 } while (read_seqretry(&xtime_lock, seq));
96 xtim = timespec_to_ktime(xts);
97 tomono = timespec_to_ktime(tom);
98 base->clock_base[CLOCK_REALTIME].softirq_time = xtim;
99 base->clock_base[CLOCK_MONOTONIC].softirq_time =
100 ktime_add(xtim, tomono);
104 * Functions and macros which are different for UP/SMP systems are kept in a
110 * We are using hashed locking: holding per_cpu(hrtimer_bases)[n].lock
111 * means that all timers which are tied to this base via timer->base are
112 * locked, and the base itself is locked too.
114 * So __run_timers/migrate_timers can safely modify all timers which could
115 * be found on the lists/queues.
117 * When the timer's base is locked, and the timer removed from list, it is
118 * possible to set timer->base = NULL and drop the lock: the timer remains
122 struct hrtimer_clock_base *lock_hrtimer_base(const struct hrtimer *timer,
123 unsigned long *flags)
125 struct hrtimer_clock_base *base;
129 if (likely(base != NULL)) {
130 spin_lock_irqsave(&base->cpu_base->lock, *flags);
131 if (likely(base == timer->base))
133 /* The timer has migrated to another CPU: */
134 spin_unlock_irqrestore(&base->cpu_base->lock, *flags);
142 * Get the preferred target CPU for NOHZ
144 static int hrtimer_get_target(int this_cpu, int pinned)
147 if (!pinned && get_sysctl_timer_migration() && idle_cpu(this_cpu)) {
148 int preferred_cpu = get_nohz_load_balancer();
150 if (preferred_cpu >= 0)
151 return preferred_cpu;
158 * With HIGHRES=y we do not migrate the timer when it is expiring
159 * before the next event on the target cpu because we cannot reprogram
160 * the target cpu hardware and we would cause it to fire late.
162 * Called with cpu_base->lock of target cpu held.
165 hrtimer_check_target(struct hrtimer *timer, struct hrtimer_clock_base *new_base)
167 #ifdef CONFIG_HIGH_RES_TIMERS
170 if (!new_base->cpu_base->hres_active)
173 expires = ktime_sub(hrtimer_get_expires(timer), new_base->offset);
174 return expires.tv64 <= new_base->cpu_base->expires_next.tv64;
181 * Switch the timer base to the current CPU when possible.
183 static inline struct hrtimer_clock_base *
184 switch_hrtimer_base(struct hrtimer *timer, struct hrtimer_clock_base *base,
187 struct hrtimer_clock_base *new_base;
188 struct hrtimer_cpu_base *new_cpu_base;
189 int this_cpu = smp_processor_id();
190 int cpu = hrtimer_get_target(this_cpu, pinned);
193 new_cpu_base = &per_cpu(hrtimer_bases, cpu);
194 new_base = &new_cpu_base->clock_base[base->index];
196 if (base != new_base) {
198 * We are trying to move timer to new_base.
199 * However we can't change timer's base while it is running,
200 * so we keep it on the same CPU. No hassle vs. reprogramming
201 * the event source in the high resolution case. The softirq
202 * code will take care of this when the timer function has
203 * completed. There is no conflict as we hold the lock until
204 * the timer is enqueued.
206 if (unlikely(hrtimer_callback_running(timer)))
209 /* See the comment in lock_timer_base() */
211 spin_unlock(&base->cpu_base->lock);
212 spin_lock(&new_base->cpu_base->lock);
214 if (cpu != this_cpu && hrtimer_check_target(timer, new_base)) {
216 spin_unlock(&new_base->cpu_base->lock);
217 spin_lock(&base->cpu_base->lock);
221 timer->base = new_base;
226 #else /* CONFIG_SMP */
228 static inline struct hrtimer_clock_base *
229 lock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
231 struct hrtimer_clock_base *base = timer->base;
233 spin_lock_irqsave(&base->cpu_base->lock, *flags);
238 # define switch_hrtimer_base(t, b, p) (b)
240 #endif /* !CONFIG_SMP */
243 * Functions for the union type storage format of ktime_t which are
244 * too large for inlining:
246 #if BITS_PER_LONG < 64
247 # ifndef CONFIG_KTIME_SCALAR
249 * ktime_add_ns - Add a scalar nanoseconds value to a ktime_t variable
251 * @nsec: the scalar nsec value to add
253 * Returns the sum of kt and nsec in ktime_t format
255 ktime_t ktime_add_ns(const ktime_t kt, u64 nsec)
259 if (likely(nsec < NSEC_PER_SEC)) {
262 unsigned long rem = do_div(nsec, NSEC_PER_SEC);
264 tmp = ktime_set((long)nsec, rem);
267 return ktime_add(kt, tmp);
270 EXPORT_SYMBOL_GPL(ktime_add_ns);
273 * ktime_sub_ns - Subtract a scalar nanoseconds value from a ktime_t variable
275 * @nsec: the scalar nsec value to subtract
277 * Returns the subtraction of @nsec from @kt in ktime_t format
279 ktime_t ktime_sub_ns(const ktime_t kt, u64 nsec)
283 if (likely(nsec < NSEC_PER_SEC)) {
286 unsigned long rem = do_div(nsec, NSEC_PER_SEC);
288 tmp = ktime_set((long)nsec, rem);
291 return ktime_sub(kt, tmp);
294 EXPORT_SYMBOL_GPL(ktime_sub_ns);
295 # endif /* !CONFIG_KTIME_SCALAR */
298 * Divide a ktime value by a nanosecond value
300 u64 ktime_divns(const ktime_t kt, s64 div)
305 dclc = ktime_to_ns(kt);
306 /* Make sure the divisor is less than 2^32: */
312 do_div(dclc, (unsigned long) div);
316 #endif /* BITS_PER_LONG >= 64 */
319 * Add two ktime values and do a safety check for overflow:
321 ktime_t ktime_add_safe(const ktime_t lhs, const ktime_t rhs)
323 ktime_t res = ktime_add(lhs, rhs);
326 * We use KTIME_SEC_MAX here, the maximum timeout which we can
327 * return to user space in a timespec:
329 if (res.tv64 < 0 || res.tv64 < lhs.tv64 || res.tv64 < rhs.tv64)
330 res = ktime_set(KTIME_SEC_MAX, 0);
335 EXPORT_SYMBOL_GPL(ktime_add_safe);
337 #ifdef CONFIG_DEBUG_OBJECTS_TIMERS
339 static struct debug_obj_descr hrtimer_debug_descr;
342 * fixup_init is called when:
343 * - an active object is initialized
345 static int hrtimer_fixup_init(void *addr, enum debug_obj_state state)
347 struct hrtimer *timer = addr;
350 case ODEBUG_STATE_ACTIVE:
351 hrtimer_cancel(timer);
352 debug_object_init(timer, &hrtimer_debug_descr);
360 * fixup_activate is called when:
361 * - an active object is activated
362 * - an unknown object is activated (might be a statically initialized object)
364 static int hrtimer_fixup_activate(void *addr, enum debug_obj_state state)
368 case ODEBUG_STATE_NOTAVAILABLE:
372 case ODEBUG_STATE_ACTIVE:
381 * fixup_free is called when:
382 * - an active object is freed
384 static int hrtimer_fixup_free(void *addr, enum debug_obj_state state)
386 struct hrtimer *timer = addr;
389 case ODEBUG_STATE_ACTIVE:
390 hrtimer_cancel(timer);
391 debug_object_free(timer, &hrtimer_debug_descr);
398 static struct debug_obj_descr hrtimer_debug_descr = {
400 .fixup_init = hrtimer_fixup_init,
401 .fixup_activate = hrtimer_fixup_activate,
402 .fixup_free = hrtimer_fixup_free,
405 static inline void debug_hrtimer_init(struct hrtimer *timer)
407 debug_object_init(timer, &hrtimer_debug_descr);
410 static inline void debug_hrtimer_activate(struct hrtimer *timer)
412 debug_object_activate(timer, &hrtimer_debug_descr);
415 static inline void debug_hrtimer_deactivate(struct hrtimer *timer)
417 debug_object_deactivate(timer, &hrtimer_debug_descr);
420 static inline void debug_hrtimer_free(struct hrtimer *timer)
422 debug_object_free(timer, &hrtimer_debug_descr);
425 static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
426 enum hrtimer_mode mode);
428 void hrtimer_init_on_stack(struct hrtimer *timer, clockid_t clock_id,
429 enum hrtimer_mode mode)
431 debug_object_init_on_stack(timer, &hrtimer_debug_descr);
432 __hrtimer_init(timer, clock_id, mode);
435 void destroy_hrtimer_on_stack(struct hrtimer *timer)
437 debug_object_free(timer, &hrtimer_debug_descr);
441 static inline void debug_hrtimer_init(struct hrtimer *timer) { }
442 static inline void debug_hrtimer_activate(struct hrtimer *timer) { }
443 static inline void debug_hrtimer_deactivate(struct hrtimer *timer) { }
447 debug_init(struct hrtimer *timer, clockid_t clockid,
448 enum hrtimer_mode mode)
450 debug_hrtimer_init(timer);
451 trace_hrtimer_init(timer, clockid, mode);
454 static inline void debug_activate(struct hrtimer *timer)
456 debug_hrtimer_activate(timer);
457 trace_hrtimer_start(timer);
460 static inline void debug_deactivate(struct hrtimer *timer)
462 debug_hrtimer_deactivate(timer);
463 trace_hrtimer_cancel(timer);
466 /* High resolution timer related functions */
467 #ifdef CONFIG_HIGH_RES_TIMERS
470 * High resolution timer enabled ?
472 static int hrtimer_hres_enabled __read_mostly = 1;
475 * Enable / Disable high resolution mode
477 static int __init setup_hrtimer_hres(char *str)
479 if (!strcmp(str, "off"))
480 hrtimer_hres_enabled = 0;
481 else if (!strcmp(str, "on"))
482 hrtimer_hres_enabled = 1;
488 __setup("highres=", setup_hrtimer_hres);
491 * hrtimer_high_res_enabled - query, if the highres mode is enabled
493 static inline int hrtimer_is_hres_enabled(void)
495 return hrtimer_hres_enabled;
499 * Is the high resolution mode active ?
501 static inline int hrtimer_hres_active(void)
503 return __get_cpu_var(hrtimer_bases).hres_active;
507 * Reprogram the event source with checking both queues for the
509 * Called with interrupts disabled and base->lock held
511 static void hrtimer_force_reprogram(struct hrtimer_cpu_base *cpu_base)
514 struct hrtimer_clock_base *base = cpu_base->clock_base;
517 cpu_base->expires_next.tv64 = KTIME_MAX;
519 for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++, base++) {
520 struct hrtimer *timer;
524 timer = rb_entry(base->first, struct hrtimer, node);
525 expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
527 * clock_was_set() has changed base->offset so the
528 * result might be negative. Fix it up to prevent a
529 * false positive in clockevents_program_event()
531 if (expires.tv64 < 0)
533 if (expires.tv64 < cpu_base->expires_next.tv64)
534 cpu_base->expires_next = expires;
537 if (cpu_base->expires_next.tv64 != KTIME_MAX)
538 tick_program_event(cpu_base->expires_next, 1);
542 * Shared reprogramming for clock_realtime and clock_monotonic
544 * When a timer is enqueued and expires earlier than the already enqueued
545 * timers, we have to check, whether it expires earlier than the timer for
546 * which the clock event device was armed.
548 * Called with interrupts disabled and base->cpu_base.lock held
550 static int hrtimer_reprogram(struct hrtimer *timer,
551 struct hrtimer_clock_base *base)
553 ktime_t *expires_next = &__get_cpu_var(hrtimer_bases).expires_next;
554 ktime_t expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
557 WARN_ON_ONCE(hrtimer_get_expires_tv64(timer) < 0);
560 * When the callback is running, we do not reprogram the clock event
561 * device. The timer callback is either running on a different CPU or
562 * the callback is executed in the hrtimer_interrupt context. The
563 * reprogramming is handled either by the softirq, which called the
564 * callback or at the end of the hrtimer_interrupt.
566 if (hrtimer_callback_running(timer))
570 * CLOCK_REALTIME timer might be requested with an absolute
571 * expiry time which is less than base->offset. Nothing wrong
572 * about that, just avoid to call into the tick code, which
573 * has now objections against negative expiry values.
575 if (expires.tv64 < 0)
578 if (expires.tv64 >= expires_next->tv64)
582 * Clockevents returns -ETIME, when the event was in the past.
584 res = tick_program_event(expires, 0);
585 if (!IS_ERR_VALUE(res))
586 *expires_next = expires;
592 * Retrigger next event is called after clock was set
594 * Called with interrupts disabled via on_each_cpu()
596 static void retrigger_next_event(void *arg)
598 struct hrtimer_cpu_base *base;
599 struct timespec realtime_offset;
602 if (!hrtimer_hres_active())
606 seq = read_seqbegin(&xtime_lock);
607 set_normalized_timespec(&realtime_offset,
608 -wall_to_monotonic.tv_sec,
609 -wall_to_monotonic.tv_nsec);
610 } while (read_seqretry(&xtime_lock, seq));
612 base = &__get_cpu_var(hrtimer_bases);
614 /* Adjust CLOCK_REALTIME offset */
615 spin_lock(&base->lock);
616 base->clock_base[CLOCK_REALTIME].offset =
617 timespec_to_ktime(realtime_offset);
619 hrtimer_force_reprogram(base);
620 spin_unlock(&base->lock);
624 * Clock realtime was set
626 * Change the offset of the realtime clock vs. the monotonic
629 * We might have to reprogram the high resolution timer interrupt. On
630 * SMP we call the architecture specific code to retrigger _all_ high
631 * resolution timer interrupts. On UP we just disable interrupts and
632 * call the high resolution interrupt code.
634 void clock_was_set(void)
636 /* Retrigger the CPU local events everywhere */
637 on_each_cpu(retrigger_next_event, NULL, 1);
641 * During resume we might have to reprogram the high resolution timer
642 * interrupt (on the local CPU):
644 void hres_timers_resume(void)
646 WARN_ONCE(!irqs_disabled(),
647 KERN_INFO "hres_timers_resume() called with IRQs enabled!");
649 retrigger_next_event(NULL);
653 * Initialize the high resolution related parts of cpu_base
655 static inline void hrtimer_init_hres(struct hrtimer_cpu_base *base)
657 base->expires_next.tv64 = KTIME_MAX;
658 base->hres_active = 0;
662 * Initialize the high resolution related parts of a hrtimer
664 static inline void hrtimer_init_timer_hres(struct hrtimer *timer)
670 * When High resolution timers are active, try to reprogram. Note, that in case
671 * the state has HRTIMER_STATE_CALLBACK set, no reprogramming and no expiry
672 * check happens. The timer gets enqueued into the rbtree. The reprogramming
673 * and expiry check is done in the hrtimer_interrupt or in the softirq.
675 static inline int hrtimer_enqueue_reprogram(struct hrtimer *timer,
676 struct hrtimer_clock_base *base,
679 if (base->cpu_base->hres_active && hrtimer_reprogram(timer, base)) {
681 spin_unlock(&base->cpu_base->lock);
682 raise_softirq_irqoff(HRTIMER_SOFTIRQ);
683 spin_lock(&base->cpu_base->lock);
685 __raise_softirq_irqoff(HRTIMER_SOFTIRQ);
694 * Switch to high resolution mode
696 static int hrtimer_switch_to_hres(void)
698 int cpu = smp_processor_id();
699 struct hrtimer_cpu_base *base = &per_cpu(hrtimer_bases, cpu);
702 if (base->hres_active)
705 local_irq_save(flags);
707 if (tick_init_highres()) {
708 local_irq_restore(flags);
709 printk(KERN_WARNING "Could not switch to high resolution "
710 "mode on CPU %d\n", cpu);
713 base->hres_active = 1;
714 base->clock_base[CLOCK_REALTIME].resolution = KTIME_HIGH_RES;
715 base->clock_base[CLOCK_MONOTONIC].resolution = KTIME_HIGH_RES;
717 tick_setup_sched_timer();
719 /* "Retrigger" the interrupt to get things going */
720 retrigger_next_event(NULL);
721 local_irq_restore(flags);
722 printk(KERN_DEBUG "Switched to high resolution mode on CPU %d\n",
729 static inline int hrtimer_hres_active(void) { return 0; }
730 static inline int hrtimer_is_hres_enabled(void) { return 0; }
731 static inline int hrtimer_switch_to_hres(void) { return 0; }
732 static inline void hrtimer_force_reprogram(struct hrtimer_cpu_base *base) { }
733 static inline int hrtimer_enqueue_reprogram(struct hrtimer *timer,
734 struct hrtimer_clock_base *base,
739 static inline void hrtimer_init_hres(struct hrtimer_cpu_base *base) { }
740 static inline void hrtimer_init_timer_hres(struct hrtimer *timer) { }
742 #endif /* CONFIG_HIGH_RES_TIMERS */
744 #ifdef CONFIG_TIMER_STATS
745 void __timer_stats_hrtimer_set_start_info(struct hrtimer *timer, void *addr)
747 if (timer->start_site)
750 timer->start_site = addr;
751 memcpy(timer->start_comm, current->comm, TASK_COMM_LEN);
752 timer->start_pid = current->pid;
757 * Counterpart to lock_hrtimer_base above:
760 void unlock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
762 spin_unlock_irqrestore(&timer->base->cpu_base->lock, *flags);
766 * hrtimer_forward - forward the timer expiry
767 * @timer: hrtimer to forward
768 * @now: forward past this time
769 * @interval: the interval to forward
771 * Forward the timer expiry so it will expire in the future.
772 * Returns the number of overruns.
774 u64 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval)
779 delta = ktime_sub(now, hrtimer_get_expires(timer));
784 if (interval.tv64 < timer->base->resolution.tv64)
785 interval.tv64 = timer->base->resolution.tv64;
787 if (unlikely(delta.tv64 >= interval.tv64)) {
788 s64 incr = ktime_to_ns(interval);
790 orun = ktime_divns(delta, incr);
791 hrtimer_add_expires_ns(timer, incr * orun);
792 if (hrtimer_get_expires_tv64(timer) > now.tv64)
795 * This (and the ktime_add() below) is the
796 * correction for exact:
800 hrtimer_add_expires(timer, interval);
804 EXPORT_SYMBOL_GPL(hrtimer_forward);
807 * enqueue_hrtimer - internal function to (re)start a timer
809 * The timer is inserted in expiry order. Insertion into the
810 * red black tree is O(log(n)). Must hold the base lock.
812 * Returns 1 when the new timer is the leftmost timer in the tree.
814 static int enqueue_hrtimer(struct hrtimer *timer,
815 struct hrtimer_clock_base *base)
817 struct rb_node **link = &base->active.rb_node;
818 struct rb_node *parent = NULL;
819 struct hrtimer *entry;
822 debug_activate(timer);
825 * Find the right place in the rbtree:
829 entry = rb_entry(parent, struct hrtimer, node);
831 * We dont care about collisions. Nodes with
832 * the same expiry time stay together.
834 if (hrtimer_get_expires_tv64(timer) <
835 hrtimer_get_expires_tv64(entry)) {
836 link = &(*link)->rb_left;
838 link = &(*link)->rb_right;
844 * Insert the timer to the rbtree and check whether it
845 * replaces the first pending timer
848 base->first = &timer->node;
850 rb_link_node(&timer->node, parent, link);
851 rb_insert_color(&timer->node, &base->active);
853 * HRTIMER_STATE_ENQUEUED is or'ed to the current state to preserve the
854 * state of a possibly running callback.
856 timer->state |= HRTIMER_STATE_ENQUEUED;
862 * __remove_hrtimer - internal function to remove a timer
864 * Caller must hold the base lock.
866 * High resolution timer mode reprograms the clock event device when the
867 * timer is the one which expires next. The caller can disable this by setting
868 * reprogram to zero. This is useful, when the context does a reprogramming
869 * anyway (e.g. timer interrupt)
871 static void __remove_hrtimer(struct hrtimer *timer,
872 struct hrtimer_clock_base *base,
873 unsigned long newstate, int reprogram)
875 if (timer->state & HRTIMER_STATE_ENQUEUED) {
877 * Remove the timer from the rbtree and replace the
878 * first entry pointer if necessary.
880 if (base->first == &timer->node) {
881 base->first = rb_next(&timer->node);
882 /* Reprogram the clock event device. if enabled */
883 if (reprogram && hrtimer_hres_active())
884 hrtimer_force_reprogram(base->cpu_base);
886 rb_erase(&timer->node, &base->active);
888 timer->state = newstate;
892 * remove hrtimer, called with base lock held
895 remove_hrtimer(struct hrtimer *timer, struct hrtimer_clock_base *base)
897 if (hrtimer_is_queued(timer)) {
901 * Remove the timer and force reprogramming when high
902 * resolution mode is active and the timer is on the current
903 * CPU. If we remove a timer on another CPU, reprogramming is
904 * skipped. The interrupt event on this CPU is fired and
905 * reprogramming happens in the interrupt handler. This is a
906 * rare case and less expensive than a smp call.
908 debug_deactivate(timer);
909 timer_stats_hrtimer_clear_start_info(timer);
910 reprogram = base->cpu_base == &__get_cpu_var(hrtimer_bases);
911 __remove_hrtimer(timer, base, HRTIMER_STATE_INACTIVE,
918 int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
919 unsigned long delta_ns, const enum hrtimer_mode mode,
922 struct hrtimer_clock_base *base, *new_base;
926 base = lock_hrtimer_base(timer, &flags);
928 /* Remove an active timer from the queue: */
929 ret = remove_hrtimer(timer, base);
931 /* Switch the timer base, if necessary: */
932 new_base = switch_hrtimer_base(timer, base, mode & HRTIMER_MODE_PINNED);
934 if (mode & HRTIMER_MODE_REL) {
935 tim = ktime_add_safe(tim, new_base->get_time());
937 * CONFIG_TIME_LOW_RES is a temporary way for architectures
938 * to signal that they simply return xtime in
939 * do_gettimeoffset(). In this case we want to round up by
940 * resolution when starting a relative timer, to avoid short
941 * timeouts. This will go away with the GTOD framework.
943 #ifdef CONFIG_TIME_LOW_RES
944 tim = ktime_add_safe(tim, base->resolution);
948 hrtimer_set_expires_range_ns(timer, tim, delta_ns);
950 timer_stats_hrtimer_set_start_info(timer);
952 leftmost = enqueue_hrtimer(timer, new_base);
955 * Only allow reprogramming if the new base is on this CPU.
956 * (it might still be on another CPU if the timer was pending)
958 * XXX send_remote_softirq() ?
960 if (leftmost && new_base->cpu_base == &__get_cpu_var(hrtimer_bases))
961 hrtimer_enqueue_reprogram(timer, new_base, wakeup);
963 unlock_hrtimer_base(timer, &flags);
969 * hrtimer_start_range_ns - (re)start an hrtimer on the current CPU
970 * @timer: the timer to be added
972 * @delta_ns: "slack" range for the timer
973 * @mode: expiry mode: absolute (HRTIMER_ABS) or relative (HRTIMER_REL)
977 * 1 when the timer was active
979 int hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
980 unsigned long delta_ns, const enum hrtimer_mode mode)
982 return __hrtimer_start_range_ns(timer, tim, delta_ns, mode, 1);
984 EXPORT_SYMBOL_GPL(hrtimer_start_range_ns);
987 * hrtimer_start - (re)start an hrtimer on the current CPU
988 * @timer: the timer to be added
990 * @mode: expiry mode: absolute (HRTIMER_ABS) or relative (HRTIMER_REL)
994 * 1 when the timer was active
997 hrtimer_start(struct hrtimer *timer, ktime_t tim, const enum hrtimer_mode mode)
999 return __hrtimer_start_range_ns(timer, tim, 0, mode, 1);
1001 EXPORT_SYMBOL_GPL(hrtimer_start);
1005 * hrtimer_try_to_cancel - try to deactivate a timer
1006 * @timer: hrtimer to stop
1009 * 0 when the timer was not active
1010 * 1 when the timer was active
1011 * -1 when the timer is currently excuting the callback function and
1014 int hrtimer_try_to_cancel(struct hrtimer *timer)
1016 struct hrtimer_clock_base *base;
1017 unsigned long flags;
1020 base = lock_hrtimer_base(timer, &flags);
1022 if (!hrtimer_callback_running(timer))
1023 ret = remove_hrtimer(timer, base);
1025 unlock_hrtimer_base(timer, &flags);
1030 EXPORT_SYMBOL_GPL(hrtimer_try_to_cancel);
1033 * hrtimer_cancel - cancel a timer and wait for the handler to finish.
1034 * @timer: the timer to be cancelled
1037 * 0 when the timer was not active
1038 * 1 when the timer was active
1040 int hrtimer_cancel(struct hrtimer *timer)
1043 int ret = hrtimer_try_to_cancel(timer);
1050 EXPORT_SYMBOL_GPL(hrtimer_cancel);
1053 * hrtimer_get_remaining - get remaining time for the timer
1054 * @timer: the timer to read
1056 ktime_t hrtimer_get_remaining(const struct hrtimer *timer)
1058 struct hrtimer_clock_base *base;
1059 unsigned long flags;
1062 base = lock_hrtimer_base(timer, &flags);
1063 rem = hrtimer_expires_remaining(timer);
1064 unlock_hrtimer_base(timer, &flags);
1068 EXPORT_SYMBOL_GPL(hrtimer_get_remaining);
1072 * hrtimer_get_next_event - get the time until next expiry event
1074 * Returns the delta to the next expiry event or KTIME_MAX if no timer
1077 ktime_t hrtimer_get_next_event(void)
1079 struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);
1080 struct hrtimer_clock_base *base = cpu_base->clock_base;
1081 ktime_t delta, mindelta = { .tv64 = KTIME_MAX };
1082 unsigned long flags;
1085 spin_lock_irqsave(&cpu_base->lock, flags);
1087 if (!hrtimer_hres_active()) {
1088 for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++, base++) {
1089 struct hrtimer *timer;
1094 timer = rb_entry(base->first, struct hrtimer, node);
1095 delta.tv64 = hrtimer_get_expires_tv64(timer);
1096 delta = ktime_sub(delta, base->get_time());
1097 if (delta.tv64 < mindelta.tv64)
1098 mindelta.tv64 = delta.tv64;
1102 spin_unlock_irqrestore(&cpu_base->lock, flags);
1104 if (mindelta.tv64 < 0)
1110 static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
1111 enum hrtimer_mode mode)
1113 struct hrtimer_cpu_base *cpu_base;
1115 memset(timer, 0, sizeof(struct hrtimer));
1117 cpu_base = &__raw_get_cpu_var(hrtimer_bases);
1119 if (clock_id == CLOCK_REALTIME && mode != HRTIMER_MODE_ABS)
1120 clock_id = CLOCK_MONOTONIC;
1122 timer->base = &cpu_base->clock_base[clock_id];
1123 hrtimer_init_timer_hres(timer);
1125 #ifdef CONFIG_TIMER_STATS
1126 timer->start_site = NULL;
1127 timer->start_pid = -1;
1128 memset(timer->start_comm, 0, TASK_COMM_LEN);
1133 * hrtimer_init - initialize a timer to the given clock
1134 * @timer: the timer to be initialized
1135 * @clock_id: the clock to be used
1136 * @mode: timer mode abs/rel
1138 void hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
1139 enum hrtimer_mode mode)
1141 debug_init(timer, clock_id, mode);
1142 __hrtimer_init(timer, clock_id, mode);
1144 EXPORT_SYMBOL_GPL(hrtimer_init);
1147 * hrtimer_get_res - get the timer resolution for a clock
1148 * @which_clock: which clock to query
1149 * @tp: pointer to timespec variable to store the resolution
1151 * Store the resolution of the clock selected by @which_clock in the
1152 * variable pointed to by @tp.
1154 int hrtimer_get_res(const clockid_t which_clock, struct timespec *tp)
1156 struct hrtimer_cpu_base *cpu_base;
1158 cpu_base = &__raw_get_cpu_var(hrtimer_bases);
1159 *tp = ktime_to_timespec(cpu_base->clock_base[which_clock].resolution);
1163 EXPORT_SYMBOL_GPL(hrtimer_get_res);
1165 static void __run_hrtimer(struct hrtimer *timer, ktime_t *now)
1167 struct hrtimer_clock_base *base = timer->base;
1168 struct hrtimer_cpu_base *cpu_base = base->cpu_base;
1169 enum hrtimer_restart (*fn)(struct hrtimer *);
1172 WARN_ON(!irqs_disabled());
1174 debug_deactivate(timer);
1175 __remove_hrtimer(timer, base, HRTIMER_STATE_CALLBACK, 0);
1176 timer_stats_account_hrtimer(timer);
1177 fn = timer->function;
1180 * Because we run timers from hardirq context, there is no chance
1181 * they get migrated to another cpu, therefore its safe to unlock
1184 spin_unlock(&cpu_base->lock);
1185 trace_hrtimer_expire_entry(timer, now);
1186 restart = fn(timer);
1187 trace_hrtimer_expire_exit(timer);
1188 spin_lock(&cpu_base->lock);
1191 * Note: We clear the CALLBACK bit after enqueue_hrtimer and
1192 * we do not reprogramm the event hardware. Happens either in
1193 * hrtimer_start_range_ns() or in hrtimer_interrupt()
1195 if (restart != HRTIMER_NORESTART) {
1196 BUG_ON(timer->state != HRTIMER_STATE_CALLBACK);
1197 enqueue_hrtimer(timer, base);
1199 timer->state &= ~HRTIMER_STATE_CALLBACK;
1202 #ifdef CONFIG_HIGH_RES_TIMERS
1204 static int force_clock_reprogram;
1207 * After 5 iteration's attempts, we consider that hrtimer_interrupt()
1208 * is hanging, which could happen with something that slows the interrupt
1209 * such as the tracing. Then we force the clock reprogramming for each future
1210 * hrtimer interrupts to avoid infinite loops and use the min_delta_ns
1211 * threshold that we will overwrite.
1212 * The next tick event will be scheduled to 3 times we currently spend on
1213 * hrtimer_interrupt(). This gives a good compromise, the cpus will spend
1214 * 1/4 of their time to process the hrtimer interrupts. This is enough to
1215 * let it running without serious starvation.
1219 hrtimer_interrupt_hanging(struct clock_event_device *dev,
1222 force_clock_reprogram = 1;
1223 dev->min_delta_ns = (unsigned long)try_time.tv64 * 3;
1224 printk(KERN_WARNING "hrtimer: interrupt too slow, "
1225 "forcing clock min delta to %lu ns\n", dev->min_delta_ns);
1228 * High resolution timer interrupt
1229 * Called with interrupts disabled
1231 void hrtimer_interrupt(struct clock_event_device *dev)
1233 struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);
1234 struct hrtimer_clock_base *base;
1235 ktime_t expires_next, now;
1239 BUG_ON(!cpu_base->hres_active);
1240 cpu_base->nr_events++;
1241 dev->next_event.tv64 = KTIME_MAX;
1244 /* 5 retries is enough to notice a hang */
1245 if (!(++nr_retries % 5))
1246 hrtimer_interrupt_hanging(dev, ktime_sub(ktime_get(), now));
1250 expires_next.tv64 = KTIME_MAX;
1252 spin_lock(&cpu_base->lock);
1254 * We set expires_next to KTIME_MAX here with cpu_base->lock
1255 * held to prevent that a timer is enqueued in our queue via
1256 * the migration code. This does not affect enqueueing of
1257 * timers which run their callback and need to be requeued on
1260 cpu_base->expires_next.tv64 = KTIME_MAX;
1262 base = cpu_base->clock_base;
1264 for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
1266 struct rb_node *node;
1268 basenow = ktime_add(now, base->offset);
1270 while ((node = base->first)) {
1271 struct hrtimer *timer;
1273 timer = rb_entry(node, struct hrtimer, node);
1276 * The immediate goal for using the softexpires is
1277 * minimizing wakeups, not running timers at the
1278 * earliest interrupt after their soft expiration.
1279 * This allows us to avoid using a Priority Search
1280 * Tree, which can answer a stabbing querry for
1281 * overlapping intervals and instead use the simple
1282 * BST we already have.
1283 * We don't add extra wakeups by delaying timers that
1284 * are right-of a not yet expired timer, because that
1285 * timer will have to trigger a wakeup anyway.
1288 if (basenow.tv64 < hrtimer_get_softexpires_tv64(timer)) {
1291 expires = ktime_sub(hrtimer_get_expires(timer),
1293 if (expires.tv64 < expires_next.tv64)
1294 expires_next = expires;
1298 __run_hrtimer(timer, &basenow);
1304 * Store the new expiry value so the migration code can verify
1307 cpu_base->expires_next = expires_next;
1308 spin_unlock(&cpu_base->lock);
1310 /* Reprogramming necessary ? */
1311 if (expires_next.tv64 != KTIME_MAX) {
1312 if (tick_program_event(expires_next, force_clock_reprogram))
1318 * local version of hrtimer_peek_ahead_timers() called with interrupts
1321 static void __hrtimer_peek_ahead_timers(void)
1323 struct tick_device *td;
1325 if (!hrtimer_hres_active())
1328 td = &__get_cpu_var(tick_cpu_device);
1329 if (td && td->evtdev)
1330 hrtimer_interrupt(td->evtdev);
1334 * hrtimer_peek_ahead_timers -- run soft-expired timers now
1336 * hrtimer_peek_ahead_timers will peek at the timer queue of
1337 * the current cpu and check if there are any timers for which
1338 * the soft expires time has passed. If any such timers exist,
1339 * they are run immediately and then removed from the timer queue.
1342 void hrtimer_peek_ahead_timers(void)
1344 unsigned long flags;
1346 local_irq_save(flags);
1347 __hrtimer_peek_ahead_timers();
1348 local_irq_restore(flags);
1351 static void run_hrtimer_softirq(struct softirq_action *h)
1353 hrtimer_peek_ahead_timers();
1356 #else /* CONFIG_HIGH_RES_TIMERS */
1358 static inline void __hrtimer_peek_ahead_timers(void) { }
1360 #endif /* !CONFIG_HIGH_RES_TIMERS */
1363 * Called from timer softirq every jiffy, expire hrtimers:
1365 * For HRT its the fall back code to run the softirq in the timer
1366 * softirq context in case the hrtimer initialization failed or has
1367 * not been done yet.
1369 void hrtimer_run_pending(void)
1371 if (hrtimer_hres_active())
1375 * This _is_ ugly: We have to check in the softirq context,
1376 * whether we can switch to highres and / or nohz mode. The
1377 * clocksource switch happens in the timer interrupt with
1378 * xtime_lock held. Notification from there only sets the
1379 * check bit in the tick_oneshot code, otherwise we might
1380 * deadlock vs. xtime_lock.
1382 if (tick_check_oneshot_change(!hrtimer_is_hres_enabled()))
1383 hrtimer_switch_to_hres();
1387 * Called from hardirq context every jiffy
1389 void hrtimer_run_queues(void)
1391 struct rb_node *node;
1392 struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);
1393 struct hrtimer_clock_base *base;
1394 int index, gettime = 1;
1396 if (hrtimer_hres_active())
1399 for (index = 0; index < HRTIMER_MAX_CLOCK_BASES; index++) {
1400 base = &cpu_base->clock_base[index];
1406 hrtimer_get_softirq_time(cpu_base);
1410 spin_lock(&cpu_base->lock);
1412 while ((node = base->first)) {
1413 struct hrtimer *timer;
1415 timer = rb_entry(node, struct hrtimer, node);
1416 if (base->softirq_time.tv64 <=
1417 hrtimer_get_expires_tv64(timer))
1420 __run_hrtimer(timer, &base->softirq_time);
1422 spin_unlock(&cpu_base->lock);
1427 * Sleep related functions:
1429 static enum hrtimer_restart hrtimer_wakeup(struct hrtimer *timer)
1431 struct hrtimer_sleeper *t =
1432 container_of(timer, struct hrtimer_sleeper, timer);
1433 struct task_struct *task = t->task;
1437 wake_up_process(task);
1439 return HRTIMER_NORESTART;
1442 void hrtimer_init_sleeper(struct hrtimer_sleeper *sl, struct task_struct *task)
1444 sl->timer.function = hrtimer_wakeup;
1448 static int __sched do_nanosleep(struct hrtimer_sleeper *t, enum hrtimer_mode mode)
1450 hrtimer_init_sleeper(t, current);
1453 set_current_state(TASK_INTERRUPTIBLE);
1454 hrtimer_start_expires(&t->timer, mode);
1455 if (!hrtimer_active(&t->timer))
1458 if (likely(t->task))
1461 hrtimer_cancel(&t->timer);
1462 mode = HRTIMER_MODE_ABS;
1464 } while (t->task && !signal_pending(current));
1466 __set_current_state(TASK_RUNNING);
1468 return t->task == NULL;
1471 static int update_rmtp(struct hrtimer *timer, struct timespec __user *rmtp)
1473 struct timespec rmt;
1476 rem = hrtimer_expires_remaining(timer);
1479 rmt = ktime_to_timespec(rem);
1481 if (copy_to_user(rmtp, &rmt, sizeof(*rmtp)))
1487 long __sched hrtimer_nanosleep_restart(struct restart_block *restart)
1489 struct hrtimer_sleeper t;
1490 struct timespec __user *rmtp;
1493 hrtimer_init_on_stack(&t.timer, restart->nanosleep.index,
1495 hrtimer_set_expires_tv64(&t.timer, restart->nanosleep.expires);
1497 if (do_nanosleep(&t, HRTIMER_MODE_ABS))
1500 rmtp = restart->nanosleep.rmtp;
1502 ret = update_rmtp(&t.timer, rmtp);
1507 /* The other values in restart are already filled in */
1508 ret = -ERESTART_RESTARTBLOCK;
1510 destroy_hrtimer_on_stack(&t.timer);
1514 long hrtimer_nanosleep(struct timespec *rqtp, struct timespec __user *rmtp,
1515 const enum hrtimer_mode mode, const clockid_t clockid)
1517 struct restart_block *restart;
1518 struct hrtimer_sleeper t;
1520 unsigned long slack;
1522 slack = current->timer_slack_ns;
1523 if (rt_task(current))
1526 hrtimer_init_on_stack(&t.timer, clockid, mode);
1527 hrtimer_set_expires_range_ns(&t.timer, timespec_to_ktime(*rqtp), slack);
1528 if (do_nanosleep(&t, mode))
1531 /* Absolute timers do not update the rmtp value and restart: */
1532 if (mode == HRTIMER_MODE_ABS) {
1533 ret = -ERESTARTNOHAND;
1538 ret = update_rmtp(&t.timer, rmtp);
1543 restart = ¤t_thread_info()->restart_block;
1544 restart->fn = hrtimer_nanosleep_restart;
1545 restart->nanosleep.index = t.timer.base->index;
1546 restart->nanosleep.rmtp = rmtp;
1547 restart->nanosleep.expires = hrtimer_get_expires_tv64(&t.timer);
1549 ret = -ERESTART_RESTARTBLOCK;
1551 destroy_hrtimer_on_stack(&t.timer);
1555 SYSCALL_DEFINE2(nanosleep, struct timespec __user *, rqtp,
1556 struct timespec __user *, rmtp)
1560 if (copy_from_user(&tu, rqtp, sizeof(tu)))
1563 if (!timespec_valid(&tu))
1566 return hrtimer_nanosleep(&tu, rmtp, HRTIMER_MODE_REL, CLOCK_MONOTONIC);
1570 * Functions related to boot-time initialization:
1572 static void __cpuinit init_hrtimers_cpu(int cpu)
1574 struct hrtimer_cpu_base *cpu_base = &per_cpu(hrtimer_bases, cpu);
1577 spin_lock_init(&cpu_base->lock);
1579 for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++)
1580 cpu_base->clock_base[i].cpu_base = cpu_base;
1582 hrtimer_init_hres(cpu_base);
1585 #ifdef CONFIG_HOTPLUG_CPU
1587 static void migrate_hrtimer_list(struct hrtimer_clock_base *old_base,
1588 struct hrtimer_clock_base *new_base)
1590 struct hrtimer *timer;
1591 struct rb_node *node;
1593 while ((node = rb_first(&old_base->active))) {
1594 timer = rb_entry(node, struct hrtimer, node);
1595 BUG_ON(hrtimer_callback_running(timer));
1596 debug_deactivate(timer);
1599 * Mark it as STATE_MIGRATE not INACTIVE otherwise the
1600 * timer could be seen as !active and just vanish away
1601 * under us on another CPU
1603 __remove_hrtimer(timer, old_base, HRTIMER_STATE_MIGRATE, 0);
1604 timer->base = new_base;
1606 * Enqueue the timers on the new cpu. This does not
1607 * reprogram the event device in case the timer
1608 * expires before the earliest on this CPU, but we run
1609 * hrtimer_interrupt after we migrated everything to
1610 * sort out already expired timers and reprogram the
1613 enqueue_hrtimer(timer, new_base);
1615 /* Clear the migration state bit */
1616 timer->state &= ~HRTIMER_STATE_MIGRATE;
1620 static void migrate_hrtimers(int scpu)
1622 struct hrtimer_cpu_base *old_base, *new_base;
1625 BUG_ON(cpu_online(scpu));
1626 tick_cancel_sched_timer(scpu);
1628 local_irq_disable();
1629 old_base = &per_cpu(hrtimer_bases, scpu);
1630 new_base = &__get_cpu_var(hrtimer_bases);
1632 * The caller is globally serialized and nobody else
1633 * takes two locks at once, deadlock is not possible.
1635 spin_lock(&new_base->lock);
1636 spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING);
1638 for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
1639 migrate_hrtimer_list(&old_base->clock_base[i],
1640 &new_base->clock_base[i]);
1643 spin_unlock(&old_base->lock);
1644 spin_unlock(&new_base->lock);
1646 /* Check, if we got expired work to do */
1647 __hrtimer_peek_ahead_timers();
1651 #endif /* CONFIG_HOTPLUG_CPU */
1653 static int __cpuinit hrtimer_cpu_notify(struct notifier_block *self,
1654 unsigned long action, void *hcpu)
1656 int scpu = (long)hcpu;
1660 case CPU_UP_PREPARE:
1661 case CPU_UP_PREPARE_FROZEN:
1662 init_hrtimers_cpu(scpu);
1665 #ifdef CONFIG_HOTPLUG_CPU
1667 case CPU_DYING_FROZEN:
1668 clockevents_notify(CLOCK_EVT_NOTIFY_CPU_DYING, &scpu);
1671 case CPU_DEAD_FROZEN:
1673 clockevents_notify(CLOCK_EVT_NOTIFY_CPU_DEAD, &scpu);
1674 migrate_hrtimers(scpu);
1686 static struct notifier_block __cpuinitdata hrtimers_nb = {
1687 .notifier_call = hrtimer_cpu_notify,
1690 void __init hrtimers_init(void)
1692 hrtimer_cpu_notify(&hrtimers_nb, (unsigned long)CPU_UP_PREPARE,
1693 (void *)(long)smp_processor_id());
1694 register_cpu_notifier(&hrtimers_nb);
1695 #ifdef CONFIG_HIGH_RES_TIMERS
1696 open_softirq(HRTIMER_SOFTIRQ, run_hrtimer_softirq);
1701 * schedule_hrtimeout_range - sleep until timeout
1702 * @expires: timeout value (ktime_t)
1703 * @delta: slack in expires timeout (ktime_t)
1704 * @mode: timer mode, HRTIMER_MODE_ABS or HRTIMER_MODE_REL
1706 * Make the current task sleep until the given expiry time has
1707 * elapsed. The routine will return immediately unless
1708 * the current task state has been set (see set_current_state()).
1710 * The @delta argument gives the kernel the freedom to schedule the
1711 * actual wakeup to a time that is both power and performance friendly.
1712 * The kernel give the normal best effort behavior for "@expires+@delta",
1713 * but may decide to fire the timer earlier, but no earlier than @expires.
1715 * You can set the task state as follows -
1717 * %TASK_UNINTERRUPTIBLE - at least @timeout time is guaranteed to
1718 * pass before the routine returns.
1720 * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
1721 * delivered to the current task.
1723 * The current task state is guaranteed to be TASK_RUNNING when this
1726 * Returns 0 when the timer has expired otherwise -EINTR
1728 int __sched schedule_hrtimeout_range(ktime_t *expires, unsigned long delta,
1729 const enum hrtimer_mode mode)
1731 struct hrtimer_sleeper t;
1734 * Optimize when a zero timeout value is given. It does not
1735 * matter whether this is an absolute or a relative time.
1737 if (expires && !expires->tv64) {
1738 __set_current_state(TASK_RUNNING);
1743 * A NULL parameter means "inifinte"
1747 __set_current_state(TASK_RUNNING);
1751 hrtimer_init_on_stack(&t.timer, CLOCK_MONOTONIC, mode);
1752 hrtimer_set_expires_range_ns(&t.timer, *expires, delta);
1754 hrtimer_init_sleeper(&t, current);
1756 hrtimer_start_expires(&t.timer, mode);
1757 if (!hrtimer_active(&t.timer))
1763 hrtimer_cancel(&t.timer);
1764 destroy_hrtimer_on_stack(&t.timer);
1766 __set_current_state(TASK_RUNNING);
1768 return !t.task ? 0 : -EINTR;
1770 EXPORT_SYMBOL_GPL(schedule_hrtimeout_range);
1773 * schedule_hrtimeout - sleep until timeout
1774 * @expires: timeout value (ktime_t)
1775 * @mode: timer mode, HRTIMER_MODE_ABS or HRTIMER_MODE_REL
1777 * Make the current task sleep until the given expiry time has
1778 * elapsed. The routine will return immediately unless
1779 * the current task state has been set (see set_current_state()).
1781 * You can set the task state as follows -
1783 * %TASK_UNINTERRUPTIBLE - at least @timeout time is guaranteed to
1784 * pass before the routine returns.
1786 * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
1787 * delivered to the current task.
1789 * The current task state is guaranteed to be TASK_RUNNING when this
1792 * Returns 0 when the timer has expired otherwise -EINTR
1794 int __sched schedule_hrtimeout(ktime_t *expires,
1795 const enum hrtimer_mode mode)
1797 return schedule_hrtimeout_range(expires, 0, mode);
1799 EXPORT_SYMBOL_GPL(schedule_hrtimeout);