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/irq.h>
36 #include <linux/module.h>
37 #include <linux/percpu.h>
38 #include <linux/hrtimer.h>
39 #include <linux/notifier.h>
40 #include <linux/syscalls.h>
41 #include <linux/kallsyms.h>
42 #include <linux/interrupt.h>
43 #include <linux/tick.h>
44 #include <linux/seq_file.h>
45 #include <linux/err.h>
47 #include <asm/uaccess.h>
50 * ktime_get - get the monotonic time in ktime_t format
52 * returns the time in ktime_t format
54 ktime_t
ktime_get(void)
60 return timespec_to_ktime(now
);
62 EXPORT_SYMBOL_GPL(ktime_get
);
65 * ktime_get_real - get the real (wall-) time in ktime_t format
67 * returns the time in ktime_t format
69 ktime_t
ktime_get_real(void)
75 return timespec_to_ktime(now
);
78 EXPORT_SYMBOL_GPL(ktime_get_real
);
83 * Note: If we want to add new timer bases, we have to skip the two
84 * clock ids captured by the cpu-timers. We do this by holding empty
85 * entries rather than doing math adjustment of the clock ids.
86 * This ensures that we capture erroneous accesses to these clock ids
87 * rather than moving them into the range of valid clock id's.
89 DEFINE_PER_CPU(struct hrtimer_cpu_base
, hrtimer_bases
) =
95 .index
= CLOCK_REALTIME
,
96 .get_time
= &ktime_get_real
,
97 .resolution
= KTIME_LOW_RES
,
100 .index
= CLOCK_MONOTONIC
,
101 .get_time
= &ktime_get
,
102 .resolution
= KTIME_LOW_RES
,
108 * ktime_get_ts - get the monotonic clock in timespec format
109 * @ts: pointer to timespec variable
111 * The function calculates the monotonic clock from the realtime
112 * clock and the wall_to_monotonic offset and stores the result
113 * in normalized timespec format in the variable pointed to by @ts.
115 void ktime_get_ts(struct timespec
*ts
)
117 struct timespec tomono
;
121 seq
= read_seqbegin(&xtime_lock
);
123 tomono
= wall_to_monotonic
;
125 } while (read_seqretry(&xtime_lock
, seq
));
127 set_normalized_timespec(ts
, ts
->tv_sec
+ tomono
.tv_sec
,
128 ts
->tv_nsec
+ tomono
.tv_nsec
);
130 EXPORT_SYMBOL_GPL(ktime_get_ts
);
133 * Get the coarse grained time at the softirq based on xtime and
136 static void hrtimer_get_softirq_time(struct hrtimer_cpu_base
*base
)
138 ktime_t xtim
, tomono
;
139 struct timespec xts
, tom
;
143 seq
= read_seqbegin(&xtime_lock
);
144 xts
= current_kernel_time();
145 tom
= wall_to_monotonic
;
146 } while (read_seqretry(&xtime_lock
, seq
));
148 xtim
= timespec_to_ktime(xts
);
149 tomono
= timespec_to_ktime(tom
);
150 base
->clock_base
[CLOCK_REALTIME
].softirq_time
= xtim
;
151 base
->clock_base
[CLOCK_MONOTONIC
].softirq_time
=
152 ktime_add(xtim
, tomono
);
156 * Helper function to check, whether the timer is running the callback
159 static inline int hrtimer_callback_running(struct hrtimer
*timer
)
161 return timer
->state
& HRTIMER_STATE_CALLBACK
;
165 * Functions and macros which are different for UP/SMP systems are kept in a
171 * We are using hashed locking: holding per_cpu(hrtimer_bases)[n].lock
172 * means that all timers which are tied to this base via timer->base are
173 * locked, and the base itself is locked too.
175 * So __run_timers/migrate_timers can safely modify all timers which could
176 * be found on the lists/queues.
178 * When the timer's base is locked, and the timer removed from list, it is
179 * possible to set timer->base = NULL and drop the lock: the timer remains
183 struct hrtimer_clock_base
*lock_hrtimer_base(const struct hrtimer
*timer
,
184 unsigned long *flags
)
186 struct hrtimer_clock_base
*base
;
190 if (likely(base
!= NULL
)) {
191 spin_lock_irqsave(&base
->cpu_base
->lock
, *flags
);
192 if (likely(base
== timer
->base
))
194 /* The timer has migrated to another CPU: */
195 spin_unlock_irqrestore(&base
->cpu_base
->lock
, *flags
);
202 * Switch the timer base to the current CPU when possible.
204 static inline struct hrtimer_clock_base
*
205 switch_hrtimer_base(struct hrtimer
*timer
, struct hrtimer_clock_base
*base
)
207 struct hrtimer_clock_base
*new_base
;
208 struct hrtimer_cpu_base
*new_cpu_base
;
210 new_cpu_base
= &__get_cpu_var(hrtimer_bases
);
211 new_base
= &new_cpu_base
->clock_base
[base
->index
];
213 if (base
!= new_base
) {
215 * We are trying to schedule the timer on the local CPU.
216 * However we can't change timer's base while it is running,
217 * so we keep it on the same CPU. No hassle vs. reprogramming
218 * the event source in the high resolution case. The softirq
219 * code will take care of this when the timer function has
220 * completed. There is no conflict as we hold the lock until
221 * the timer is enqueued.
223 if (unlikely(hrtimer_callback_running(timer
)))
226 /* See the comment in lock_timer_base() */
228 spin_unlock(&base
->cpu_base
->lock
);
229 spin_lock(&new_base
->cpu_base
->lock
);
230 timer
->base
= new_base
;
235 #else /* CONFIG_SMP */
237 static inline struct hrtimer_clock_base
*
238 lock_hrtimer_base(const struct hrtimer
*timer
, unsigned long *flags
)
240 struct hrtimer_clock_base
*base
= timer
->base
;
242 spin_lock_irqsave(&base
->cpu_base
->lock
, *flags
);
247 # define switch_hrtimer_base(t, b) (b)
249 #endif /* !CONFIG_SMP */
252 * Functions for the union type storage format of ktime_t which are
253 * too large for inlining:
255 #if BITS_PER_LONG < 64
256 # ifndef CONFIG_KTIME_SCALAR
258 * ktime_add_ns - Add a scalar nanoseconds value to a ktime_t variable
260 * @nsec: the scalar nsec value to add
262 * Returns the sum of kt and nsec in ktime_t format
264 ktime_t
ktime_add_ns(const ktime_t kt
, u64 nsec
)
268 if (likely(nsec
< NSEC_PER_SEC
)) {
271 unsigned long rem
= do_div(nsec
, NSEC_PER_SEC
);
273 tmp
= ktime_set((long)nsec
, rem
);
276 return ktime_add(kt
, tmp
);
279 EXPORT_SYMBOL_GPL(ktime_add_ns
);
282 * ktime_sub_ns - Subtract a scalar nanoseconds value from a ktime_t variable
284 * @nsec: the scalar nsec value to subtract
286 * Returns the subtraction of @nsec from @kt in ktime_t format
288 ktime_t
ktime_sub_ns(const ktime_t kt
, u64 nsec
)
292 if (likely(nsec
< NSEC_PER_SEC
)) {
295 unsigned long rem
= do_div(nsec
, NSEC_PER_SEC
);
297 tmp
= ktime_set((long)nsec
, rem
);
300 return ktime_sub(kt
, tmp
);
303 EXPORT_SYMBOL_GPL(ktime_sub_ns
);
304 # endif /* !CONFIG_KTIME_SCALAR */
307 * Divide a ktime value by a nanosecond value
309 u64
ktime_divns(const ktime_t kt
, s64 div
)
314 dclc
= dns
= ktime_to_ns(kt
);
316 /* Make sure the divisor is less than 2^32: */
322 do_div(dclc
, (unsigned long) div
);
326 #endif /* BITS_PER_LONG >= 64 */
329 * Add two ktime values and do a safety check for overflow:
331 ktime_t
ktime_add_safe(const ktime_t lhs
, const ktime_t rhs
)
333 ktime_t res
= ktime_add(lhs
, rhs
);
336 * We use KTIME_SEC_MAX here, the maximum timeout which we can
337 * return to user space in a timespec:
339 if (res
.tv64
< 0 || res
.tv64
< lhs
.tv64
|| res
.tv64
< rhs
.tv64
)
340 res
= ktime_set(KTIME_SEC_MAX
, 0);
346 * Check, whether the timer is on the callback pending list
348 static inline int hrtimer_cb_pending(const struct hrtimer
*timer
)
350 return timer
->state
& HRTIMER_STATE_PENDING
;
354 * Remove a timer from the callback pending list
356 static inline void hrtimer_remove_cb_pending(struct hrtimer
*timer
)
358 list_del_init(&timer
->cb_entry
);
361 /* High resolution timer related functions */
362 #ifdef CONFIG_HIGH_RES_TIMERS
365 * High resolution timer enabled ?
367 static int hrtimer_hres_enabled __read_mostly
= 1;
370 * Enable / Disable high resolution mode
372 static int __init
setup_hrtimer_hres(char *str
)
374 if (!strcmp(str
, "off"))
375 hrtimer_hres_enabled
= 0;
376 else if (!strcmp(str
, "on"))
377 hrtimer_hres_enabled
= 1;
383 __setup("highres=", setup_hrtimer_hres
);
386 * hrtimer_high_res_enabled - query, if the highres mode is enabled
388 static inline int hrtimer_is_hres_enabled(void)
390 return hrtimer_hres_enabled
;
394 * Is the high resolution mode active ?
396 static inline int hrtimer_hres_active(void)
398 return __get_cpu_var(hrtimer_bases
).hres_active
;
402 * Reprogram the event source with checking both queues for the
404 * Called with interrupts disabled and base->lock held
406 static void hrtimer_force_reprogram(struct hrtimer_cpu_base
*cpu_base
)
409 struct hrtimer_clock_base
*base
= cpu_base
->clock_base
;
412 cpu_base
->expires_next
.tv64
= KTIME_MAX
;
414 for (i
= 0; i
< HRTIMER_MAX_CLOCK_BASES
; i
++, base
++) {
415 struct hrtimer
*timer
;
419 timer
= rb_entry(base
->first
, struct hrtimer
, node
);
420 expires
= ktime_sub(timer
->expires
, base
->offset
);
421 if (expires
.tv64
< cpu_base
->expires_next
.tv64
)
422 cpu_base
->expires_next
= expires
;
425 if (cpu_base
->expires_next
.tv64
!= KTIME_MAX
)
426 tick_program_event(cpu_base
->expires_next
, 1);
430 * Shared reprogramming for clock_realtime and clock_monotonic
432 * When a timer is enqueued and expires earlier than the already enqueued
433 * timers, we have to check, whether it expires earlier than the timer for
434 * which the clock event device was armed.
436 * Called with interrupts disabled and base->cpu_base.lock held
438 static int hrtimer_reprogram(struct hrtimer
*timer
,
439 struct hrtimer_clock_base
*base
)
441 ktime_t
*expires_next
= &__get_cpu_var(hrtimer_bases
).expires_next
;
442 ktime_t expires
= ktime_sub(timer
->expires
, base
->offset
);
446 * When the callback is running, we do not reprogram the clock event
447 * device. The timer callback is either running on a different CPU or
448 * the callback is executed in the hrtimer_interrupt context. The
449 * reprogramming is handled either by the softirq, which called the
450 * callback or at the end of the hrtimer_interrupt.
452 if (hrtimer_callback_running(timer
))
455 if (expires
.tv64
>= expires_next
->tv64
)
459 * Clockevents returns -ETIME, when the event was in the past.
461 res
= tick_program_event(expires
, 0);
462 if (!IS_ERR_VALUE(res
))
463 *expires_next
= expires
;
469 * Retrigger next event is called after clock was set
471 * Called with interrupts disabled via on_each_cpu()
473 static void retrigger_next_event(void *arg
)
475 struct hrtimer_cpu_base
*base
;
476 struct timespec realtime_offset
;
479 if (!hrtimer_hres_active())
483 seq
= read_seqbegin(&xtime_lock
);
484 set_normalized_timespec(&realtime_offset
,
485 -wall_to_monotonic
.tv_sec
,
486 -wall_to_monotonic
.tv_nsec
);
487 } while (read_seqretry(&xtime_lock
, seq
));
489 base
= &__get_cpu_var(hrtimer_bases
);
491 /* Adjust CLOCK_REALTIME offset */
492 spin_lock(&base
->lock
);
493 base
->clock_base
[CLOCK_REALTIME
].offset
=
494 timespec_to_ktime(realtime_offset
);
496 hrtimer_force_reprogram(base
);
497 spin_unlock(&base
->lock
);
501 * Clock realtime was set
503 * Change the offset of the realtime clock vs. the monotonic
506 * We might have to reprogram the high resolution timer interrupt. On
507 * SMP we call the architecture specific code to retrigger _all_ high
508 * resolution timer interrupts. On UP we just disable interrupts and
509 * call the high resolution interrupt code.
511 void clock_was_set(void)
513 /* Retrigger the CPU local events everywhere */
514 on_each_cpu(retrigger_next_event
, NULL
, 0, 1);
518 * During resume we might have to reprogram the high resolution timer
519 * interrupt (on the local CPU):
521 void hres_timers_resume(void)
523 WARN_ON_ONCE(num_online_cpus() > 1);
525 /* Retrigger the CPU local events: */
526 retrigger_next_event(NULL
);
530 * Initialize the high resolution related parts of cpu_base
532 static inline void hrtimer_init_hres(struct hrtimer_cpu_base
*base
)
534 base
->expires_next
.tv64
= KTIME_MAX
;
535 base
->hres_active
= 0;
539 * Initialize the high resolution related parts of a hrtimer
541 static inline void hrtimer_init_timer_hres(struct hrtimer
*timer
)
546 * When High resolution timers are active, try to reprogram. Note, that in case
547 * the state has HRTIMER_STATE_CALLBACK set, no reprogramming and no expiry
548 * check happens. The timer gets enqueued into the rbtree. The reprogramming
549 * and expiry check is done in the hrtimer_interrupt or in the softirq.
551 static inline int hrtimer_enqueue_reprogram(struct hrtimer
*timer
,
552 struct hrtimer_clock_base
*base
)
554 if (base
->cpu_base
->hres_active
&& hrtimer_reprogram(timer
, base
)) {
556 /* Timer is expired, act upon the callback mode */
557 switch(timer
->cb_mode
) {
558 case HRTIMER_CB_IRQSAFE_NO_RESTART
:
560 * We can call the callback from here. No restart
561 * happens, so no danger of recursion
563 BUG_ON(timer
->function(timer
) != HRTIMER_NORESTART
);
565 case HRTIMER_CB_IRQSAFE_NO_SOFTIRQ
:
567 * This is solely for the sched tick emulation with
568 * dynamic tick support to ensure that we do not
569 * restart the tick right on the edge and end up with
570 * the tick timer in the softirq ! The calling site
571 * takes care of this.
574 case HRTIMER_CB_IRQSAFE
:
575 case HRTIMER_CB_SOFTIRQ
:
577 * Move everything else into the softirq pending list !
579 list_add_tail(&timer
->cb_entry
,
580 &base
->cpu_base
->cb_pending
);
581 timer
->state
= HRTIMER_STATE_PENDING
;
582 raise_softirq(HRTIMER_SOFTIRQ
);
592 * Switch to high resolution mode
594 static int hrtimer_switch_to_hres(void)
596 int cpu
= smp_processor_id();
597 struct hrtimer_cpu_base
*base
= &per_cpu(hrtimer_bases
, cpu
);
600 if (base
->hres_active
)
603 local_irq_save(flags
);
605 if (tick_init_highres()) {
606 local_irq_restore(flags
);
607 printk(KERN_WARNING
"Could not switch to high resolution "
608 "mode on CPU %d\n", cpu
);
611 base
->hres_active
= 1;
612 base
->clock_base
[CLOCK_REALTIME
].resolution
= KTIME_HIGH_RES
;
613 base
->clock_base
[CLOCK_MONOTONIC
].resolution
= KTIME_HIGH_RES
;
615 tick_setup_sched_timer();
617 /* "Retrigger" the interrupt to get things going */
618 retrigger_next_event(NULL
);
619 local_irq_restore(flags
);
620 printk(KERN_DEBUG
"Switched to high resolution mode on CPU %d\n",
627 static inline int hrtimer_hres_active(void) { return 0; }
628 static inline int hrtimer_is_hres_enabled(void) { return 0; }
629 static inline int hrtimer_switch_to_hres(void) { return 0; }
630 static inline void hrtimer_force_reprogram(struct hrtimer_cpu_base
*base
) { }
631 static inline int hrtimer_enqueue_reprogram(struct hrtimer
*timer
,
632 struct hrtimer_clock_base
*base
)
636 static inline void hrtimer_init_hres(struct hrtimer_cpu_base
*base
) { }
637 static inline void hrtimer_init_timer_hres(struct hrtimer
*timer
) { }
638 static inline int hrtimer_reprogram(struct hrtimer
*timer
,
639 struct hrtimer_clock_base
*base
)
644 #endif /* CONFIG_HIGH_RES_TIMERS */
646 #ifdef CONFIG_TIMER_STATS
647 void __timer_stats_hrtimer_set_start_info(struct hrtimer
*timer
, void *addr
)
649 if (timer
->start_site
)
652 timer
->start_site
= addr
;
653 memcpy(timer
->start_comm
, current
->comm
, TASK_COMM_LEN
);
654 timer
->start_pid
= current
->pid
;
659 * Counterpart to lock_hrtimer_base above:
662 void unlock_hrtimer_base(const struct hrtimer
*timer
, unsigned long *flags
)
664 spin_unlock_irqrestore(&timer
->base
->cpu_base
->lock
, *flags
);
668 * hrtimer_forward - forward the timer expiry
669 * @timer: hrtimer to forward
670 * @now: forward past this time
671 * @interval: the interval to forward
673 * Forward the timer expiry so it will expire in the future.
674 * Returns the number of overruns.
676 u64
hrtimer_forward(struct hrtimer
*timer
, ktime_t now
, ktime_t interval
)
681 delta
= ktime_sub(now
, timer
->expires
);
686 if (interval
.tv64
< timer
->base
->resolution
.tv64
)
687 interval
.tv64
= timer
->base
->resolution
.tv64
;
689 if (unlikely(delta
.tv64
>= interval
.tv64
)) {
690 s64 incr
= ktime_to_ns(interval
);
692 orun
= ktime_divns(delta
, incr
);
693 timer
->expires
= ktime_add_ns(timer
->expires
, incr
* orun
);
694 if (timer
->expires
.tv64
> now
.tv64
)
697 * This (and the ktime_add() below) is the
698 * correction for exact:
702 timer
->expires
= ktime_add_safe(timer
->expires
, interval
);
706 EXPORT_SYMBOL_GPL(hrtimer_forward
);
709 * enqueue_hrtimer - internal function to (re)start a timer
711 * The timer is inserted in expiry order. Insertion into the
712 * red black tree is O(log(n)). Must hold the base lock.
714 static void enqueue_hrtimer(struct hrtimer
*timer
,
715 struct hrtimer_clock_base
*base
, int reprogram
)
717 struct rb_node
**link
= &base
->active
.rb_node
;
718 struct rb_node
*parent
= NULL
;
719 struct hrtimer
*entry
;
723 * Find the right place in the rbtree:
727 entry
= rb_entry(parent
, struct hrtimer
, node
);
729 * We dont care about collisions. Nodes with
730 * the same expiry time stay together.
732 if (timer
->expires
.tv64
< entry
->expires
.tv64
) {
733 link
= &(*link
)->rb_left
;
735 link
= &(*link
)->rb_right
;
741 * Insert the timer to the rbtree and check whether it
742 * replaces the first pending timer
746 * Reprogram the clock event device. When the timer is already
747 * expired hrtimer_enqueue_reprogram has either called the
748 * callback or added it to the pending list and raised the
751 * This is a NOP for !HIGHRES
753 if (reprogram
&& hrtimer_enqueue_reprogram(timer
, base
))
756 base
->first
= &timer
->node
;
759 rb_link_node(&timer
->node
, parent
, link
);
760 rb_insert_color(&timer
->node
, &base
->active
);
762 * HRTIMER_STATE_ENQUEUED is or'ed to the current state to preserve the
763 * state of a possibly running callback.
765 timer
->state
|= HRTIMER_STATE_ENQUEUED
;
769 * __remove_hrtimer - internal function to remove a timer
771 * Caller must hold the base lock.
773 * High resolution timer mode reprograms the clock event device when the
774 * timer is the one which expires next. The caller can disable this by setting
775 * reprogram to zero. This is useful, when the context does a reprogramming
776 * anyway (e.g. timer interrupt)
778 static void __remove_hrtimer(struct hrtimer
*timer
,
779 struct hrtimer_clock_base
*base
,
780 unsigned long newstate
, int reprogram
)
782 /* High res. callback list. NOP for !HIGHRES */
783 if (hrtimer_cb_pending(timer
))
784 hrtimer_remove_cb_pending(timer
);
787 * Remove the timer from the rbtree and replace the
788 * first entry pointer if necessary.
790 if (base
->first
== &timer
->node
) {
791 base
->first
= rb_next(&timer
->node
);
792 /* Reprogram the clock event device. if enabled */
793 if (reprogram
&& hrtimer_hres_active())
794 hrtimer_force_reprogram(base
->cpu_base
);
796 rb_erase(&timer
->node
, &base
->active
);
798 timer
->state
= newstate
;
802 * remove hrtimer, called with base lock held
805 remove_hrtimer(struct hrtimer
*timer
, struct hrtimer_clock_base
*base
)
807 if (hrtimer_is_queued(timer
)) {
811 * Remove the timer and force reprogramming when high
812 * resolution mode is active and the timer is on the current
813 * CPU. If we remove a timer on another CPU, reprogramming is
814 * skipped. The interrupt event on this CPU is fired and
815 * reprogramming happens in the interrupt handler. This is a
816 * rare case and less expensive than a smp call.
818 timer_stats_hrtimer_clear_start_info(timer
);
819 reprogram
= base
->cpu_base
== &__get_cpu_var(hrtimer_bases
);
820 __remove_hrtimer(timer
, base
, HRTIMER_STATE_INACTIVE
,
828 * hrtimer_start - (re)start an relative timer on the current CPU
829 * @timer: the timer to be added
831 * @mode: expiry mode: absolute (HRTIMER_ABS) or relative (HRTIMER_REL)
835 * 1 when the timer was active
838 hrtimer_start(struct hrtimer
*timer
, ktime_t tim
, const enum hrtimer_mode mode
)
840 struct hrtimer_clock_base
*base
, *new_base
;
844 base
= lock_hrtimer_base(timer
, &flags
);
846 /* Remove an active timer from the queue: */
847 ret
= remove_hrtimer(timer
, base
);
849 /* Switch the timer base, if necessary: */
850 new_base
= switch_hrtimer_base(timer
, base
);
852 if (mode
== HRTIMER_MODE_REL
) {
853 tim
= ktime_add_safe(tim
, new_base
->get_time());
855 * CONFIG_TIME_LOW_RES is a temporary way for architectures
856 * to signal that they simply return xtime in
857 * do_gettimeoffset(). In this case we want to round up by
858 * resolution when starting a relative timer, to avoid short
859 * timeouts. This will go away with the GTOD framework.
861 #ifdef CONFIG_TIME_LOW_RES
862 tim
= ktime_add_safe(tim
, base
->resolution
);
865 timer
->expires
= tim
;
867 timer_stats_hrtimer_set_start_info(timer
);
870 * Only allow reprogramming if the new base is on this CPU.
871 * (it might still be on another CPU if the timer was pending)
873 enqueue_hrtimer(timer
, new_base
,
874 new_base
->cpu_base
== &__get_cpu_var(hrtimer_bases
));
876 unlock_hrtimer_base(timer
, &flags
);
880 EXPORT_SYMBOL_GPL(hrtimer_start
);
883 * hrtimer_try_to_cancel - try to deactivate a timer
884 * @timer: hrtimer to stop
887 * 0 when the timer was not active
888 * 1 when the timer was active
889 * -1 when the timer is currently excuting the callback function and
892 int hrtimer_try_to_cancel(struct hrtimer
*timer
)
894 struct hrtimer_clock_base
*base
;
898 base
= lock_hrtimer_base(timer
, &flags
);
900 if (!hrtimer_callback_running(timer
))
901 ret
= remove_hrtimer(timer
, base
);
903 unlock_hrtimer_base(timer
, &flags
);
908 EXPORT_SYMBOL_GPL(hrtimer_try_to_cancel
);
911 * hrtimer_cancel - cancel a timer and wait for the handler to finish.
912 * @timer: the timer to be cancelled
915 * 0 when the timer was not active
916 * 1 when the timer was active
918 int hrtimer_cancel(struct hrtimer
*timer
)
921 int ret
= hrtimer_try_to_cancel(timer
);
928 EXPORT_SYMBOL_GPL(hrtimer_cancel
);
931 * hrtimer_get_remaining - get remaining time for the timer
932 * @timer: the timer to read
934 ktime_t
hrtimer_get_remaining(const struct hrtimer
*timer
)
936 struct hrtimer_clock_base
*base
;
940 base
= lock_hrtimer_base(timer
, &flags
);
941 rem
= ktime_sub(timer
->expires
, base
->get_time());
942 unlock_hrtimer_base(timer
, &flags
);
946 EXPORT_SYMBOL_GPL(hrtimer_get_remaining
);
948 #if defined(CONFIG_NO_IDLE_HZ) || defined(CONFIG_NO_HZ)
950 * hrtimer_get_next_event - get the time until next expiry event
952 * Returns the delta to the next expiry event or KTIME_MAX if no timer
955 ktime_t
hrtimer_get_next_event(void)
957 struct hrtimer_cpu_base
*cpu_base
= &__get_cpu_var(hrtimer_bases
);
958 struct hrtimer_clock_base
*base
= cpu_base
->clock_base
;
959 ktime_t delta
, mindelta
= { .tv64
= KTIME_MAX
};
963 spin_lock_irqsave(&cpu_base
->lock
, flags
);
965 if (!hrtimer_hres_active()) {
966 for (i
= 0; i
< HRTIMER_MAX_CLOCK_BASES
; i
++, base
++) {
967 struct hrtimer
*timer
;
972 timer
= rb_entry(base
->first
, struct hrtimer
, node
);
973 delta
.tv64
= timer
->expires
.tv64
;
974 delta
= ktime_sub(delta
, base
->get_time());
975 if (delta
.tv64
< mindelta
.tv64
)
976 mindelta
.tv64
= delta
.tv64
;
980 spin_unlock_irqrestore(&cpu_base
->lock
, flags
);
982 if (mindelta
.tv64
< 0)
989 * hrtimer_init - initialize a timer to the given clock
990 * @timer: the timer to be initialized
991 * @clock_id: the clock to be used
992 * @mode: timer mode abs/rel
994 void hrtimer_init(struct hrtimer
*timer
, clockid_t clock_id
,
995 enum hrtimer_mode mode
)
997 struct hrtimer_cpu_base
*cpu_base
;
999 memset(timer
, 0, sizeof(struct hrtimer
));
1001 cpu_base
= &__raw_get_cpu_var(hrtimer_bases
);
1003 if (clock_id
== CLOCK_REALTIME
&& mode
!= HRTIMER_MODE_ABS
)
1004 clock_id
= CLOCK_MONOTONIC
;
1006 timer
->base
= &cpu_base
->clock_base
[clock_id
];
1007 INIT_LIST_HEAD(&timer
->cb_entry
);
1008 hrtimer_init_timer_hres(timer
);
1010 #ifdef CONFIG_TIMER_STATS
1011 timer
->start_site
= NULL
;
1012 timer
->start_pid
= -1;
1013 memset(timer
->start_comm
, 0, TASK_COMM_LEN
);
1016 EXPORT_SYMBOL_GPL(hrtimer_init
);
1019 * hrtimer_get_res - get the timer resolution for a clock
1020 * @which_clock: which clock to query
1021 * @tp: pointer to timespec variable to store the resolution
1023 * Store the resolution of the clock selected by @which_clock in the
1024 * variable pointed to by @tp.
1026 int hrtimer_get_res(const clockid_t which_clock
, struct timespec
*tp
)
1028 struct hrtimer_cpu_base
*cpu_base
;
1030 cpu_base
= &__raw_get_cpu_var(hrtimer_bases
);
1031 *tp
= ktime_to_timespec(cpu_base
->clock_base
[which_clock
].resolution
);
1035 EXPORT_SYMBOL_GPL(hrtimer_get_res
);
1037 static void run_hrtimer_pending(struct hrtimer_cpu_base
*cpu_base
)
1039 spin_lock_irq(&cpu_base
->lock
);
1041 while (!list_empty(&cpu_base
->cb_pending
)) {
1042 enum hrtimer_restart (*fn
)(struct hrtimer
*);
1043 struct hrtimer
*timer
;
1046 timer
= list_entry(cpu_base
->cb_pending
.next
,
1047 struct hrtimer
, cb_entry
);
1049 timer_stats_account_hrtimer(timer
);
1051 fn
= timer
->function
;
1052 __remove_hrtimer(timer
, timer
->base
, HRTIMER_STATE_CALLBACK
, 0);
1053 spin_unlock_irq(&cpu_base
->lock
);
1055 restart
= fn(timer
);
1057 spin_lock_irq(&cpu_base
->lock
);
1059 timer
->state
&= ~HRTIMER_STATE_CALLBACK
;
1060 if (restart
== HRTIMER_RESTART
) {
1061 BUG_ON(hrtimer_active(timer
));
1063 * Enqueue the timer, allow reprogramming of the event
1066 enqueue_hrtimer(timer
, timer
->base
, 1);
1067 } else if (hrtimer_active(timer
)) {
1069 * If the timer was rearmed on another CPU, reprogram
1072 if (timer
->base
->first
== &timer
->node
)
1073 hrtimer_reprogram(timer
, timer
->base
);
1076 spin_unlock_irq(&cpu_base
->lock
);
1079 static void __run_hrtimer(struct hrtimer
*timer
)
1081 struct hrtimer_clock_base
*base
= timer
->base
;
1082 struct hrtimer_cpu_base
*cpu_base
= base
->cpu_base
;
1083 enum hrtimer_restart (*fn
)(struct hrtimer
*);
1086 __remove_hrtimer(timer
, base
, HRTIMER_STATE_CALLBACK
, 0);
1087 timer_stats_account_hrtimer(timer
);
1089 fn
= timer
->function
;
1090 if (timer
->cb_mode
== HRTIMER_CB_IRQSAFE_NO_SOFTIRQ
) {
1092 * Used for scheduler timers, avoid lock inversion with
1093 * rq->lock and tasklist_lock.
1095 * These timers are required to deal with enqueue expiry
1096 * themselves and are not allowed to migrate.
1098 spin_unlock(&cpu_base
->lock
);
1099 restart
= fn(timer
);
1100 spin_lock(&cpu_base
->lock
);
1102 restart
= fn(timer
);
1105 * Note: We clear the CALLBACK bit after enqueue_hrtimer to avoid
1106 * reprogramming of the event hardware. This happens at the end of this
1109 if (restart
!= HRTIMER_NORESTART
) {
1110 BUG_ON(timer
->state
!= HRTIMER_STATE_CALLBACK
);
1111 enqueue_hrtimer(timer
, base
, 0);
1113 timer
->state
&= ~HRTIMER_STATE_CALLBACK
;
1116 #ifdef CONFIG_HIGH_RES_TIMERS
1119 * High resolution timer interrupt
1120 * Called with interrupts disabled
1122 void hrtimer_interrupt(struct clock_event_device
*dev
)
1124 struct hrtimer_cpu_base
*cpu_base
= &__get_cpu_var(hrtimer_bases
);
1125 struct hrtimer_clock_base
*base
;
1126 ktime_t expires_next
, now
;
1129 BUG_ON(!cpu_base
->hres_active
);
1130 cpu_base
->nr_events
++;
1131 dev
->next_event
.tv64
= KTIME_MAX
;
1136 expires_next
.tv64
= KTIME_MAX
;
1138 base
= cpu_base
->clock_base
;
1140 for (i
= 0; i
< HRTIMER_MAX_CLOCK_BASES
; i
++) {
1142 struct rb_node
*node
;
1144 spin_lock(&cpu_base
->lock
);
1146 basenow
= ktime_add(now
, base
->offset
);
1148 while ((node
= base
->first
)) {
1149 struct hrtimer
*timer
;
1151 timer
= rb_entry(node
, struct hrtimer
, node
);
1153 if (basenow
.tv64
< timer
->expires
.tv64
) {
1156 expires
= ktime_sub(timer
->expires
,
1158 if (expires
.tv64
< expires_next
.tv64
)
1159 expires_next
= expires
;
1163 /* Move softirq callbacks to the pending list */
1164 if (timer
->cb_mode
== HRTIMER_CB_SOFTIRQ
) {
1165 __remove_hrtimer(timer
, base
,
1166 HRTIMER_STATE_PENDING
, 0);
1167 list_add_tail(&timer
->cb_entry
,
1168 &base
->cpu_base
->cb_pending
);
1173 __run_hrtimer(timer
);
1175 spin_unlock(&cpu_base
->lock
);
1179 cpu_base
->expires_next
= expires_next
;
1181 /* Reprogramming necessary ? */
1182 if (expires_next
.tv64
!= KTIME_MAX
) {
1183 if (tick_program_event(expires_next
, 0))
1187 /* Raise softirq ? */
1189 raise_softirq(HRTIMER_SOFTIRQ
);
1192 static void run_hrtimer_softirq(struct softirq_action
*h
)
1194 run_hrtimer_pending(&__get_cpu_var(hrtimer_bases
));
1197 #endif /* CONFIG_HIGH_RES_TIMERS */
1200 * Called from timer softirq every jiffy, expire hrtimers:
1202 * For HRT its the fall back code to run the softirq in the timer
1203 * softirq context in case the hrtimer initialization failed or has
1204 * not been done yet.
1206 void hrtimer_run_pending(void)
1208 struct hrtimer_cpu_base
*cpu_base
= &__get_cpu_var(hrtimer_bases
);
1210 if (hrtimer_hres_active())
1214 * This _is_ ugly: We have to check in the softirq context,
1215 * whether we can switch to highres and / or nohz mode. The
1216 * clocksource switch happens in the timer interrupt with
1217 * xtime_lock held. Notification from there only sets the
1218 * check bit in the tick_oneshot code, otherwise we might
1219 * deadlock vs. xtime_lock.
1221 if (tick_check_oneshot_change(!hrtimer_is_hres_enabled()))
1222 hrtimer_switch_to_hres();
1224 run_hrtimer_pending(cpu_base
);
1228 * Called from hardirq context every jiffy
1230 static inline void run_hrtimer_queue(struct hrtimer_cpu_base
*cpu_base
,
1233 struct rb_node
*node
;
1234 struct hrtimer_clock_base
*base
= &cpu_base
->clock_base
[index
];
1239 if (base
->get_softirq_time
)
1240 base
->softirq_time
= base
->get_softirq_time();
1242 spin_lock(&cpu_base
->lock
);
1244 while ((node
= base
->first
)) {
1245 struct hrtimer
*timer
;
1247 timer
= rb_entry(node
, struct hrtimer
, node
);
1248 if (base
->softirq_time
.tv64
<= timer
->expires
.tv64
)
1251 if (timer
->cb_mode
== HRTIMER_CB_SOFTIRQ
) {
1252 __remove_hrtimer(timer
, base
, HRTIMER_STATE_PENDING
, 0);
1253 list_add_tail(&timer
->cb_entry
,
1254 &base
->cpu_base
->cb_pending
);
1258 __run_hrtimer(timer
);
1260 spin_unlock(&cpu_base
->lock
);
1263 void hrtimer_run_queues(void)
1265 struct hrtimer_cpu_base
*cpu_base
= &__get_cpu_var(hrtimer_bases
);
1268 if (hrtimer_hres_active())
1271 hrtimer_get_softirq_time(cpu_base
);
1273 for (i
= 0; i
< HRTIMER_MAX_CLOCK_BASES
; i
++)
1274 run_hrtimer_queue(cpu_base
, i
);
1278 * Sleep related functions:
1280 static enum hrtimer_restart
hrtimer_wakeup(struct hrtimer
*timer
)
1282 struct hrtimer_sleeper
*t
=
1283 container_of(timer
, struct hrtimer_sleeper
, timer
);
1284 struct task_struct
*task
= t
->task
;
1288 wake_up_process(task
);
1290 return HRTIMER_NORESTART
;
1293 void hrtimer_init_sleeper(struct hrtimer_sleeper
*sl
, struct task_struct
*task
)
1295 sl
->timer
.function
= hrtimer_wakeup
;
1297 #ifdef CONFIG_HIGH_RES_TIMERS
1298 sl
->timer
.cb_mode
= HRTIMER_CB_IRQSAFE_NO_SOFTIRQ
;
1302 static int __sched
do_nanosleep(struct hrtimer_sleeper
*t
, enum hrtimer_mode mode
)
1304 hrtimer_init_sleeper(t
, current
);
1307 set_current_state(TASK_INTERRUPTIBLE
);
1308 hrtimer_start(&t
->timer
, t
->timer
.expires
, mode
);
1309 if (!hrtimer_active(&t
->timer
))
1312 if (likely(t
->task
))
1315 hrtimer_cancel(&t
->timer
);
1316 mode
= HRTIMER_MODE_ABS
;
1318 } while (t
->task
&& !signal_pending(current
));
1320 __set_current_state(TASK_RUNNING
);
1322 return t
->task
== NULL
;
1325 static int update_rmtp(struct hrtimer
*timer
, struct timespec __user
*rmtp
)
1327 struct timespec rmt
;
1330 rem
= ktime_sub(timer
->expires
, timer
->base
->get_time());
1333 rmt
= ktime_to_timespec(rem
);
1335 if (copy_to_user(rmtp
, &rmt
, sizeof(*rmtp
)))
1341 long __sched
hrtimer_nanosleep_restart(struct restart_block
*restart
)
1343 struct hrtimer_sleeper t
;
1344 struct timespec __user
*rmtp
;
1346 hrtimer_init(&t
.timer
, restart
->arg0
, HRTIMER_MODE_ABS
);
1347 t
.timer
.expires
.tv64
= ((u64
)restart
->arg3
<< 32) | (u64
) restart
->arg2
;
1349 if (do_nanosleep(&t
, HRTIMER_MODE_ABS
))
1352 rmtp
= (struct timespec __user
*)restart
->arg1
;
1354 int ret
= update_rmtp(&t
.timer
, rmtp
);
1359 /* The other values in restart are already filled in */
1360 return -ERESTART_RESTARTBLOCK
;
1363 long hrtimer_nanosleep(struct timespec
*rqtp
, struct timespec __user
*rmtp
,
1364 const enum hrtimer_mode mode
, const clockid_t clockid
)
1366 struct restart_block
*restart
;
1367 struct hrtimer_sleeper t
;
1369 hrtimer_init(&t
.timer
, clockid
, mode
);
1370 t
.timer
.expires
= timespec_to_ktime(*rqtp
);
1371 if (do_nanosleep(&t
, mode
))
1374 /* Absolute timers do not update the rmtp value and restart: */
1375 if (mode
== HRTIMER_MODE_ABS
)
1376 return -ERESTARTNOHAND
;
1379 int ret
= update_rmtp(&t
.timer
, rmtp
);
1384 restart
= ¤t_thread_info()->restart_block
;
1385 restart
->fn
= hrtimer_nanosleep_restart
;
1386 restart
->arg0
= (unsigned long) t
.timer
.base
->index
;
1387 restart
->arg1
= (unsigned long) rmtp
;
1388 restart
->arg2
= t
.timer
.expires
.tv64
& 0xFFFFFFFF;
1389 restart
->arg3
= t
.timer
.expires
.tv64
>> 32;
1391 return -ERESTART_RESTARTBLOCK
;
1395 sys_nanosleep(struct timespec __user
*rqtp
, struct timespec __user
*rmtp
)
1399 if (copy_from_user(&tu
, rqtp
, sizeof(tu
)))
1402 if (!timespec_valid(&tu
))
1405 return hrtimer_nanosleep(&tu
, rmtp
, HRTIMER_MODE_REL
, CLOCK_MONOTONIC
);
1409 * Functions related to boot-time initialization:
1411 static void __cpuinit
init_hrtimers_cpu(int cpu
)
1413 struct hrtimer_cpu_base
*cpu_base
= &per_cpu(hrtimer_bases
, cpu
);
1416 spin_lock_init(&cpu_base
->lock
);
1417 lockdep_set_class(&cpu_base
->lock
, &cpu_base
->lock_key
);
1419 for (i
= 0; i
< HRTIMER_MAX_CLOCK_BASES
; i
++)
1420 cpu_base
->clock_base
[i
].cpu_base
= cpu_base
;
1422 INIT_LIST_HEAD(&cpu_base
->cb_pending
);
1423 hrtimer_init_hres(cpu_base
);
1426 #ifdef CONFIG_HOTPLUG_CPU
1428 static void migrate_hrtimer_list(struct hrtimer_clock_base
*old_base
,
1429 struct hrtimer_clock_base
*new_base
)
1431 struct hrtimer
*timer
;
1432 struct rb_node
*node
;
1434 while ((node
= rb_first(&old_base
->active
))) {
1435 timer
= rb_entry(node
, struct hrtimer
, node
);
1436 BUG_ON(hrtimer_callback_running(timer
));
1437 __remove_hrtimer(timer
, old_base
, HRTIMER_STATE_INACTIVE
, 0);
1438 timer
->base
= new_base
;
1440 * Enqueue the timer. Allow reprogramming of the event device
1442 enqueue_hrtimer(timer
, new_base
, 1);
1446 static void migrate_hrtimers(int cpu
)
1448 struct hrtimer_cpu_base
*old_base
, *new_base
;
1451 BUG_ON(cpu_online(cpu
));
1452 old_base
= &per_cpu(hrtimer_bases
, cpu
);
1453 new_base
= &get_cpu_var(hrtimer_bases
);
1455 tick_cancel_sched_timer(cpu
);
1457 local_irq_disable();
1458 double_spin_lock(&new_base
->lock
, &old_base
->lock
,
1459 smp_processor_id() < cpu
);
1461 for (i
= 0; i
< HRTIMER_MAX_CLOCK_BASES
; i
++) {
1462 migrate_hrtimer_list(&old_base
->clock_base
[i
],
1463 &new_base
->clock_base
[i
]);
1466 double_spin_unlock(&new_base
->lock
, &old_base
->lock
,
1467 smp_processor_id() < cpu
);
1469 put_cpu_var(hrtimer_bases
);
1471 #endif /* CONFIG_HOTPLUG_CPU */
1473 static int __cpuinit
hrtimer_cpu_notify(struct notifier_block
*self
,
1474 unsigned long action
, void *hcpu
)
1476 unsigned int cpu
= (long)hcpu
;
1480 case CPU_UP_PREPARE
:
1481 case CPU_UP_PREPARE_FROZEN
:
1482 init_hrtimers_cpu(cpu
);
1485 #ifdef CONFIG_HOTPLUG_CPU
1487 case CPU_DEAD_FROZEN
:
1488 clockevents_notify(CLOCK_EVT_NOTIFY_CPU_DEAD
, &cpu
);
1489 migrate_hrtimers(cpu
);
1500 static struct notifier_block __cpuinitdata hrtimers_nb
= {
1501 .notifier_call
= hrtimer_cpu_notify
,
1504 void __init
hrtimers_init(void)
1506 hrtimer_cpu_notify(&hrtimers_nb
, (unsigned long)CPU_UP_PREPARE
,
1507 (void *)(long)smp_processor_id());
1508 register_cpu_notifier(&hrtimers_nb
);
1509 #ifdef CONFIG_HIGH_RES_TIMERS
1510 open_softirq(HRTIMER_SOFTIRQ
, run_hrtimer_softirq
, NULL
);