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
);
64 * ktime_get_real - get the real (wall-) time in ktime_t format
66 * returns the time in ktime_t format
68 ktime_t
ktime_get_real(void)
74 return timespec_to_ktime(now
);
77 EXPORT_SYMBOL_GPL(ktime_get_real
);
82 * Note: If we want to add new timer bases, we have to skip the two
83 * clock ids captured by the cpu-timers. We do this by holding empty
84 * entries rather than doing math adjustment of the clock ids.
85 * This ensures that we capture erroneous accesses to these clock ids
86 * rather than moving them into the range of valid clock id's.
88 DEFINE_PER_CPU(struct hrtimer_cpu_base
, hrtimer_bases
) =
94 .index
= CLOCK_REALTIME
,
95 .get_time
= &ktime_get_real
,
96 .resolution
= KTIME_LOW_RES
,
99 .index
= CLOCK_MONOTONIC
,
100 .get_time
= &ktime_get
,
101 .resolution
= KTIME_LOW_RES
,
107 * ktime_get_ts - get the monotonic clock in timespec format
108 * @ts: pointer to timespec variable
110 * The function calculates the monotonic clock from the realtime
111 * clock and the wall_to_monotonic offset and stores the result
112 * in normalized timespec format in the variable pointed to by @ts.
114 void ktime_get_ts(struct timespec
*ts
)
116 struct timespec tomono
;
120 seq
= read_seqbegin(&xtime_lock
);
122 tomono
= wall_to_monotonic
;
124 } while (read_seqretry(&xtime_lock
, seq
));
126 set_normalized_timespec(ts
, ts
->tv_sec
+ tomono
.tv_sec
,
127 ts
->tv_nsec
+ tomono
.tv_nsec
);
129 EXPORT_SYMBOL_GPL(ktime_get_ts
);
132 * Get the coarse grained time at the softirq based on xtime and
135 static void hrtimer_get_softirq_time(struct hrtimer_cpu_base
*base
)
137 ktime_t xtim
, tomono
;
142 seq
= read_seqbegin(&xtime_lock
);
144 getnstimeofday(&xts
);
148 } while (read_seqretry(&xtime_lock
, seq
));
150 xtim
= timespec_to_ktime(xts
);
151 tomono
= timespec_to_ktime(wall_to_monotonic
);
152 base
->clock_base
[CLOCK_REALTIME
].softirq_time
= xtim
;
153 base
->clock_base
[CLOCK_MONOTONIC
].softirq_time
=
154 ktime_add(xtim
, tomono
);
158 * Helper function to check, whether the timer is running the callback
161 static inline int hrtimer_callback_running(struct hrtimer
*timer
)
163 return timer
->state
& HRTIMER_STATE_CALLBACK
;
167 * Functions and macros which are different for UP/SMP systems are kept in a
173 * We are using hashed locking: holding per_cpu(hrtimer_bases)[n].lock
174 * means that all timers which are tied to this base via timer->base are
175 * locked, and the base itself is locked too.
177 * So __run_timers/migrate_timers can safely modify all timers which could
178 * be found on the lists/queues.
180 * When the timer's base is locked, and the timer removed from list, it is
181 * possible to set timer->base = NULL and drop the lock: the timer remains
185 struct hrtimer_clock_base
*lock_hrtimer_base(const struct hrtimer
*timer
,
186 unsigned long *flags
)
188 struct hrtimer_clock_base
*base
;
192 if (likely(base
!= NULL
)) {
193 spin_lock_irqsave(&base
->cpu_base
->lock
, *flags
);
194 if (likely(base
== timer
->base
))
196 /* The timer has migrated to another CPU: */
197 spin_unlock_irqrestore(&base
->cpu_base
->lock
, *flags
);
204 * Switch the timer base to the current CPU when possible.
206 static inline struct hrtimer_clock_base
*
207 switch_hrtimer_base(struct hrtimer
*timer
, struct hrtimer_clock_base
*base
)
209 struct hrtimer_clock_base
*new_base
;
210 struct hrtimer_cpu_base
*new_cpu_base
;
212 new_cpu_base
= &__get_cpu_var(hrtimer_bases
);
213 new_base
= &new_cpu_base
->clock_base
[base
->index
];
215 if (base
!= new_base
) {
217 * We are trying to schedule the timer on the local CPU.
218 * However we can't change timer's base while it is running,
219 * so we keep it on the same CPU. No hassle vs. reprogramming
220 * the event source in the high resolution case. The softirq
221 * code will take care of this when the timer function has
222 * completed. There is no conflict as we hold the lock until
223 * the timer is enqueued.
225 if (unlikely(hrtimer_callback_running(timer
)))
228 /* See the comment in lock_timer_base() */
230 spin_unlock(&base
->cpu_base
->lock
);
231 spin_lock(&new_base
->cpu_base
->lock
);
232 timer
->base
= new_base
;
237 #else /* CONFIG_SMP */
239 static inline struct hrtimer_clock_base
*
240 lock_hrtimer_base(const struct hrtimer
*timer
, unsigned long *flags
)
242 struct hrtimer_clock_base
*base
= timer
->base
;
244 spin_lock_irqsave(&base
->cpu_base
->lock
, *flags
);
249 # define switch_hrtimer_base(t, b) (b)
251 #endif /* !CONFIG_SMP */
254 * Functions for the union type storage format of ktime_t which are
255 * too large for inlining:
257 #if BITS_PER_LONG < 64
258 # ifndef CONFIG_KTIME_SCALAR
260 * ktime_add_ns - Add a scalar nanoseconds value to a ktime_t variable
262 * @nsec: the scalar nsec value to add
264 * Returns the sum of kt and nsec in ktime_t format
266 ktime_t
ktime_add_ns(const ktime_t kt
, u64 nsec
)
270 if (likely(nsec
< NSEC_PER_SEC
)) {
273 unsigned long rem
= do_div(nsec
, NSEC_PER_SEC
);
275 tmp
= ktime_set((long)nsec
, rem
);
278 return ktime_add(kt
, tmp
);
280 # endif /* !CONFIG_KTIME_SCALAR */
283 * Divide a ktime value by a nanosecond value
285 unsigned long ktime_divns(const ktime_t kt
, s64 div
)
290 dclc
= dns
= ktime_to_ns(kt
);
292 /* Make sure the divisor is less than 2^32: */
298 do_div(dclc
, (unsigned long) div
);
300 return (unsigned long) dclc
;
302 #endif /* BITS_PER_LONG >= 64 */
304 /* High resolution timer related functions */
305 #ifdef CONFIG_HIGH_RES_TIMERS
308 * High resolution timer enabled ?
310 static int hrtimer_hres_enabled __read_mostly
= 1;
313 * Enable / Disable high resolution mode
315 static int __init
setup_hrtimer_hres(char *str
)
317 if (!strcmp(str
, "off"))
318 hrtimer_hres_enabled
= 0;
319 else if (!strcmp(str
, "on"))
320 hrtimer_hres_enabled
= 1;
326 __setup("highres=", setup_hrtimer_hres
);
329 * hrtimer_high_res_enabled - query, if the highres mode is enabled
331 static inline int hrtimer_is_hres_enabled(void)
333 return hrtimer_hres_enabled
;
337 * Is the high resolution mode active ?
339 static inline int hrtimer_hres_active(void)
341 return __get_cpu_var(hrtimer_bases
).hres_active
;
345 * Reprogram the event source with checking both queues for the
347 * Called with interrupts disabled and base->lock held
349 static void hrtimer_force_reprogram(struct hrtimer_cpu_base
*cpu_base
)
352 struct hrtimer_clock_base
*base
= cpu_base
->clock_base
;
355 cpu_base
->expires_next
.tv64
= KTIME_MAX
;
357 for (i
= 0; i
< HRTIMER_MAX_CLOCK_BASES
; i
++, base
++) {
358 struct hrtimer
*timer
;
362 timer
= rb_entry(base
->first
, struct hrtimer
, node
);
363 expires
= ktime_sub(timer
->expires
, base
->offset
);
364 if (expires
.tv64
< cpu_base
->expires_next
.tv64
)
365 cpu_base
->expires_next
= expires
;
368 if (cpu_base
->expires_next
.tv64
!= KTIME_MAX
)
369 tick_program_event(cpu_base
->expires_next
, 1);
373 * Shared reprogramming for clock_realtime and clock_monotonic
375 * When a timer is enqueued and expires earlier than the already enqueued
376 * timers, we have to check, whether it expires earlier than the timer for
377 * which the clock event device was armed.
379 * Called with interrupts disabled and base->cpu_base.lock held
381 static int hrtimer_reprogram(struct hrtimer
*timer
,
382 struct hrtimer_clock_base
*base
)
384 ktime_t
*expires_next
= &__get_cpu_var(hrtimer_bases
).expires_next
;
385 ktime_t expires
= ktime_sub(timer
->expires
, base
->offset
);
389 * When the callback is running, we do not reprogram the clock event
390 * device. The timer callback is either running on a different CPU or
391 * the callback is executed in the hrtimer_interupt context. The
392 * reprogramming is handled either by the softirq, which called the
393 * callback or at the end of the hrtimer_interrupt.
395 if (hrtimer_callback_running(timer
))
398 if (expires
.tv64
>= expires_next
->tv64
)
402 * Clockevents returns -ETIME, when the event was in the past.
404 res
= tick_program_event(expires
, 0);
405 if (!IS_ERR_VALUE(res
))
406 *expires_next
= expires
;
412 * Retrigger next event is called after clock was set
414 * Called with interrupts disabled via on_each_cpu()
416 static void retrigger_next_event(void *arg
)
418 struct hrtimer_cpu_base
*base
;
419 struct timespec realtime_offset
;
422 if (!hrtimer_hres_active())
426 seq
= read_seqbegin(&xtime_lock
);
427 set_normalized_timespec(&realtime_offset
,
428 -wall_to_monotonic
.tv_sec
,
429 -wall_to_monotonic
.tv_nsec
);
430 } while (read_seqretry(&xtime_lock
, seq
));
432 base
= &__get_cpu_var(hrtimer_bases
);
434 /* Adjust CLOCK_REALTIME offset */
435 spin_lock(&base
->lock
);
436 base
->clock_base
[CLOCK_REALTIME
].offset
=
437 timespec_to_ktime(realtime_offset
);
439 hrtimer_force_reprogram(base
);
440 spin_unlock(&base
->lock
);
444 * Clock realtime was set
446 * Change the offset of the realtime clock vs. the monotonic
449 * We might have to reprogram the high resolution timer interrupt. On
450 * SMP we call the architecture specific code to retrigger _all_ high
451 * resolution timer interrupts. On UP we just disable interrupts and
452 * call the high resolution interrupt code.
454 void clock_was_set(void)
456 /* Retrigger the CPU local events everywhere */
457 on_each_cpu(retrigger_next_event
, NULL
, 0, 1);
461 * Check, whether the timer is on the callback pending list
463 static inline int hrtimer_cb_pending(const struct hrtimer
*timer
)
465 return timer
->state
& HRTIMER_STATE_PENDING
;
469 * Remove a timer from the callback pending list
471 static inline void hrtimer_remove_cb_pending(struct hrtimer
*timer
)
473 list_del_init(&timer
->cb_entry
);
477 * Initialize the high resolution related parts of cpu_base
479 static inline void hrtimer_init_hres(struct hrtimer_cpu_base
*base
)
481 base
->expires_next
.tv64
= KTIME_MAX
;
482 base
->hres_active
= 0;
483 INIT_LIST_HEAD(&base
->cb_pending
);
487 * Initialize the high resolution related parts of a hrtimer
489 static inline void hrtimer_init_timer_hres(struct hrtimer
*timer
)
491 INIT_LIST_HEAD(&timer
->cb_entry
);
495 * When High resolution timers are active, try to reprogram. Note, that in case
496 * the state has HRTIMER_STATE_CALLBACK set, no reprogramming and no expiry
497 * check happens. The timer gets enqueued into the rbtree. The reprogramming
498 * and expiry check is done in the hrtimer_interrupt or in the softirq.
500 static inline int hrtimer_enqueue_reprogram(struct hrtimer
*timer
,
501 struct hrtimer_clock_base
*base
)
503 if (base
->cpu_base
->hres_active
&& hrtimer_reprogram(timer
, base
)) {
505 /* Timer is expired, act upon the callback mode */
506 switch(timer
->cb_mode
) {
507 case HRTIMER_CB_IRQSAFE_NO_RESTART
:
509 * We can call the callback from here. No restart
510 * happens, so no danger of recursion
512 BUG_ON(timer
->function(timer
) != HRTIMER_NORESTART
);
514 case HRTIMER_CB_IRQSAFE_NO_SOFTIRQ
:
516 * This is solely for the sched tick emulation with
517 * dynamic tick support to ensure that we do not
518 * restart the tick right on the edge and end up with
519 * the tick timer in the softirq ! The calling site
520 * takes care of this.
523 case HRTIMER_CB_IRQSAFE
:
524 case HRTIMER_CB_SOFTIRQ
:
526 * Move everything else into the softirq pending list !
528 list_add_tail(&timer
->cb_entry
,
529 &base
->cpu_base
->cb_pending
);
530 timer
->state
= HRTIMER_STATE_PENDING
;
531 raise_softirq(HRTIMER_SOFTIRQ
);
541 * Switch to high resolution mode
543 static int hrtimer_switch_to_hres(void)
545 struct hrtimer_cpu_base
*base
= &__get_cpu_var(hrtimer_bases
);
548 if (base
->hres_active
)
551 local_irq_save(flags
);
553 if (tick_init_highres()) {
554 local_irq_restore(flags
);
557 base
->hres_active
= 1;
558 base
->clock_base
[CLOCK_REALTIME
].resolution
= KTIME_HIGH_RES
;
559 base
->clock_base
[CLOCK_MONOTONIC
].resolution
= KTIME_HIGH_RES
;
561 tick_setup_sched_timer();
563 /* "Retrigger" the interrupt to get things going */
564 retrigger_next_event(NULL
);
565 local_irq_restore(flags
);
566 printk(KERN_INFO
"Switched to high resolution mode on CPU %d\n",
573 static inline int hrtimer_hres_active(void) { return 0; }
574 static inline int hrtimer_is_hres_enabled(void) { return 0; }
575 static inline int hrtimer_switch_to_hres(void) { return 0; }
576 static inline void hrtimer_force_reprogram(struct hrtimer_cpu_base
*base
) { }
577 static inline int hrtimer_enqueue_reprogram(struct hrtimer
*timer
,
578 struct hrtimer_clock_base
*base
)
582 static inline int hrtimer_cb_pending(struct hrtimer
*timer
) { return 0; }
583 static inline void hrtimer_remove_cb_pending(struct hrtimer
*timer
) { }
584 static inline void hrtimer_init_hres(struct hrtimer_cpu_base
*base
) { }
585 static inline void hrtimer_init_timer_hres(struct hrtimer
*timer
) { }
587 #endif /* CONFIG_HIGH_RES_TIMERS */
589 #ifdef CONFIG_TIMER_STATS
590 void __timer_stats_hrtimer_set_start_info(struct hrtimer
*timer
, void *addr
)
592 if (timer
->start_site
)
595 timer
->start_site
= addr
;
596 memcpy(timer
->start_comm
, current
->comm
, TASK_COMM_LEN
);
597 timer
->start_pid
= current
->pid
;
602 * Counterpart to lock_timer_base above:
605 void unlock_hrtimer_base(const struct hrtimer
*timer
, unsigned long *flags
)
607 spin_unlock_irqrestore(&timer
->base
->cpu_base
->lock
, *flags
);
611 * hrtimer_forward - forward the timer expiry
612 * @timer: hrtimer to forward
613 * @now: forward past this time
614 * @interval: the interval to forward
616 * Forward the timer expiry so it will expire in the future.
617 * Returns the number of overruns.
620 hrtimer_forward(struct hrtimer
*timer
, ktime_t now
, ktime_t interval
)
622 unsigned long orun
= 1;
625 delta
= ktime_sub(now
, timer
->expires
);
630 if (interval
.tv64
< timer
->base
->resolution
.tv64
)
631 interval
.tv64
= timer
->base
->resolution
.tv64
;
633 if (unlikely(delta
.tv64
>= interval
.tv64
)) {
634 s64 incr
= ktime_to_ns(interval
);
636 orun
= ktime_divns(delta
, incr
);
637 timer
->expires
= ktime_add_ns(timer
->expires
, incr
* orun
);
638 if (timer
->expires
.tv64
> now
.tv64
)
641 * This (and the ktime_add() below) is the
642 * correction for exact:
646 timer
->expires
= ktime_add(timer
->expires
, interval
);
648 * Make sure, that the result did not wrap with a very large
651 if (timer
->expires
.tv64
< 0)
652 timer
->expires
= ktime_set(KTIME_SEC_MAX
, 0);
658 * enqueue_hrtimer - internal function to (re)start a timer
660 * The timer is inserted in expiry order. Insertion into the
661 * red black tree is O(log(n)). Must hold the base lock.
663 static void enqueue_hrtimer(struct hrtimer
*timer
,
664 struct hrtimer_clock_base
*base
, int reprogram
)
666 struct rb_node
**link
= &base
->active
.rb_node
;
667 struct rb_node
*parent
= NULL
;
668 struct hrtimer
*entry
;
671 * Find the right place in the rbtree:
675 entry
= rb_entry(parent
, struct hrtimer
, node
);
677 * We dont care about collisions. Nodes with
678 * the same expiry time stay together.
680 if (timer
->expires
.tv64
< entry
->expires
.tv64
)
681 link
= &(*link
)->rb_left
;
683 link
= &(*link
)->rb_right
;
687 * Insert the timer to the rbtree and check whether it
688 * replaces the first pending timer
690 if (!base
->first
|| timer
->expires
.tv64
<
691 rb_entry(base
->first
, struct hrtimer
, node
)->expires
.tv64
) {
693 * Reprogram the clock event device. When the timer is already
694 * expired hrtimer_enqueue_reprogram has either called the
695 * callback or added it to the pending list and raised the
698 * This is a NOP for !HIGHRES
700 if (reprogram
&& hrtimer_enqueue_reprogram(timer
, base
))
703 base
->first
= &timer
->node
;
706 rb_link_node(&timer
->node
, parent
, link
);
707 rb_insert_color(&timer
->node
, &base
->active
);
709 * HRTIMER_STATE_ENQUEUED is or'ed to the current state to preserve the
710 * state of a possibly running callback.
712 timer
->state
|= HRTIMER_STATE_ENQUEUED
;
716 * __remove_hrtimer - internal function to remove a timer
718 * Caller must hold the base lock.
720 * High resolution timer mode reprograms the clock event device when the
721 * timer is the one which expires next. The caller can disable this by setting
722 * reprogram to zero. This is useful, when the context does a reprogramming
723 * anyway (e.g. timer interrupt)
725 static void __remove_hrtimer(struct hrtimer
*timer
,
726 struct hrtimer_clock_base
*base
,
727 unsigned long newstate
, int reprogram
)
729 /* High res. callback list. NOP for !HIGHRES */
730 if (hrtimer_cb_pending(timer
))
731 hrtimer_remove_cb_pending(timer
);
734 * Remove the timer from the rbtree and replace the
735 * first entry pointer if necessary.
737 if (base
->first
== &timer
->node
) {
738 base
->first
= rb_next(&timer
->node
);
739 /* Reprogram the clock event device. if enabled */
740 if (reprogram
&& hrtimer_hres_active())
741 hrtimer_force_reprogram(base
->cpu_base
);
743 rb_erase(&timer
->node
, &base
->active
);
745 timer
->state
= newstate
;
749 * remove hrtimer, called with base lock held
752 remove_hrtimer(struct hrtimer
*timer
, struct hrtimer_clock_base
*base
)
754 if (hrtimer_is_queued(timer
)) {
758 * Remove the timer and force reprogramming when high
759 * resolution mode is active and the timer is on the current
760 * CPU. If we remove a timer on another CPU, reprogramming is
761 * skipped. The interrupt event on this CPU is fired and
762 * reprogramming happens in the interrupt handler. This is a
763 * rare case and less expensive than a smp call.
765 timer_stats_hrtimer_clear_start_info(timer
);
766 reprogram
= base
->cpu_base
== &__get_cpu_var(hrtimer_bases
);
767 __remove_hrtimer(timer
, base
, HRTIMER_STATE_INACTIVE
,
775 * hrtimer_start - (re)start an relative timer on the current CPU
776 * @timer: the timer to be added
778 * @mode: expiry mode: absolute (HRTIMER_ABS) or relative (HRTIMER_REL)
782 * 1 when the timer was active
785 hrtimer_start(struct hrtimer
*timer
, ktime_t tim
, const enum hrtimer_mode mode
)
787 struct hrtimer_clock_base
*base
, *new_base
;
791 base
= lock_hrtimer_base(timer
, &flags
);
793 /* Remove an active timer from the queue: */
794 ret
= remove_hrtimer(timer
, base
);
796 /* Switch the timer base, if necessary: */
797 new_base
= switch_hrtimer_base(timer
, base
);
799 if (mode
== HRTIMER_MODE_REL
) {
800 tim
= ktime_add(tim
, new_base
->get_time());
802 * CONFIG_TIME_LOW_RES is a temporary way for architectures
803 * to signal that they simply return xtime in
804 * do_gettimeoffset(). In this case we want to round up by
805 * resolution when starting a relative timer, to avoid short
806 * timeouts. This will go away with the GTOD framework.
808 #ifdef CONFIG_TIME_LOW_RES
809 tim
= ktime_add(tim
, base
->resolution
);
812 timer
->expires
= tim
;
814 timer_stats_hrtimer_set_start_info(timer
);
816 enqueue_hrtimer(timer
, new_base
, base
== new_base
);
818 unlock_hrtimer_base(timer
, &flags
);
822 EXPORT_SYMBOL_GPL(hrtimer_start
);
825 * hrtimer_try_to_cancel - try to deactivate a timer
826 * @timer: hrtimer to stop
829 * 0 when the timer was not active
830 * 1 when the timer was active
831 * -1 when the timer is currently excuting the callback function and
834 int hrtimer_try_to_cancel(struct hrtimer
*timer
)
836 struct hrtimer_clock_base
*base
;
840 base
= lock_hrtimer_base(timer
, &flags
);
842 if (!hrtimer_callback_running(timer
))
843 ret
= remove_hrtimer(timer
, base
);
845 unlock_hrtimer_base(timer
, &flags
);
850 EXPORT_SYMBOL_GPL(hrtimer_try_to_cancel
);
853 * hrtimer_cancel - cancel a timer and wait for the handler to finish.
854 * @timer: the timer to be cancelled
857 * 0 when the timer was not active
858 * 1 when the timer was active
860 int hrtimer_cancel(struct hrtimer
*timer
)
863 int ret
= hrtimer_try_to_cancel(timer
);
870 EXPORT_SYMBOL_GPL(hrtimer_cancel
);
873 * hrtimer_get_remaining - get remaining time for the timer
874 * @timer: the timer to read
876 ktime_t
hrtimer_get_remaining(const struct hrtimer
*timer
)
878 struct hrtimer_clock_base
*base
;
882 base
= lock_hrtimer_base(timer
, &flags
);
883 rem
= ktime_sub(timer
->expires
, base
->get_time());
884 unlock_hrtimer_base(timer
, &flags
);
888 EXPORT_SYMBOL_GPL(hrtimer_get_remaining
);
890 #if defined(CONFIG_NO_IDLE_HZ) || defined(CONFIG_NO_HZ)
892 * hrtimer_get_next_event - get the time until next expiry event
894 * Returns the delta to the next expiry event or KTIME_MAX if no timer
897 ktime_t
hrtimer_get_next_event(void)
899 struct hrtimer_cpu_base
*cpu_base
= &__get_cpu_var(hrtimer_bases
);
900 struct hrtimer_clock_base
*base
= cpu_base
->clock_base
;
901 ktime_t delta
, mindelta
= { .tv64
= KTIME_MAX
};
905 spin_lock_irqsave(&cpu_base
->lock
, flags
);
907 if (!hrtimer_hres_active()) {
908 for (i
= 0; i
< HRTIMER_MAX_CLOCK_BASES
; i
++, base
++) {
909 struct hrtimer
*timer
;
914 timer
= rb_entry(base
->first
, struct hrtimer
, node
);
915 delta
.tv64
= timer
->expires
.tv64
;
916 delta
= ktime_sub(delta
, base
->get_time());
917 if (delta
.tv64
< mindelta
.tv64
)
918 mindelta
.tv64
= delta
.tv64
;
922 spin_unlock_irqrestore(&cpu_base
->lock
, flags
);
924 if (mindelta
.tv64
< 0)
931 * hrtimer_init - initialize a timer to the given clock
932 * @timer: the timer to be initialized
933 * @clock_id: the clock to be used
934 * @mode: timer mode abs/rel
936 void hrtimer_init(struct hrtimer
*timer
, clockid_t clock_id
,
937 enum hrtimer_mode mode
)
939 struct hrtimer_cpu_base
*cpu_base
;
941 memset(timer
, 0, sizeof(struct hrtimer
));
943 cpu_base
= &__raw_get_cpu_var(hrtimer_bases
);
945 if (clock_id
== CLOCK_REALTIME
&& mode
!= HRTIMER_MODE_ABS
)
946 clock_id
= CLOCK_MONOTONIC
;
948 timer
->base
= &cpu_base
->clock_base
[clock_id
];
949 hrtimer_init_timer_hres(timer
);
951 #ifdef CONFIG_TIMER_STATS
952 timer
->start_site
= NULL
;
953 timer
->start_pid
= -1;
954 memset(timer
->start_comm
, 0, TASK_COMM_LEN
);
957 EXPORT_SYMBOL_GPL(hrtimer_init
);
960 * hrtimer_get_res - get the timer resolution for a clock
961 * @which_clock: which clock to query
962 * @tp: pointer to timespec variable to store the resolution
964 * Store the resolution of the clock selected by @which_clock in the
965 * variable pointed to by @tp.
967 int hrtimer_get_res(const clockid_t which_clock
, struct timespec
*tp
)
969 struct hrtimer_cpu_base
*cpu_base
;
971 cpu_base
= &__raw_get_cpu_var(hrtimer_bases
);
972 *tp
= ktime_to_timespec(cpu_base
->clock_base
[which_clock
].resolution
);
976 EXPORT_SYMBOL_GPL(hrtimer_get_res
);
978 #ifdef CONFIG_HIGH_RES_TIMERS
981 * High resolution timer interrupt
982 * Called with interrupts disabled
984 void hrtimer_interrupt(struct clock_event_device
*dev
)
986 struct hrtimer_cpu_base
*cpu_base
= &__get_cpu_var(hrtimer_bases
);
987 struct hrtimer_clock_base
*base
;
988 ktime_t expires_next
, now
;
991 BUG_ON(!cpu_base
->hres_active
);
992 cpu_base
->nr_events
++;
993 dev
->next_event
.tv64
= KTIME_MAX
;
998 expires_next
.tv64
= KTIME_MAX
;
1000 base
= cpu_base
->clock_base
;
1002 for (i
= 0; i
< HRTIMER_MAX_CLOCK_BASES
; i
++) {
1004 struct rb_node
*node
;
1006 spin_lock(&cpu_base
->lock
);
1008 basenow
= ktime_add(now
, base
->offset
);
1010 while ((node
= base
->first
)) {
1011 struct hrtimer
*timer
;
1013 timer
= rb_entry(node
, struct hrtimer
, node
);
1015 if (basenow
.tv64
< timer
->expires
.tv64
) {
1018 expires
= ktime_sub(timer
->expires
,
1020 if (expires
.tv64
< expires_next
.tv64
)
1021 expires_next
= expires
;
1025 /* Move softirq callbacks to the pending list */
1026 if (timer
->cb_mode
== HRTIMER_CB_SOFTIRQ
) {
1027 __remove_hrtimer(timer
, base
,
1028 HRTIMER_STATE_PENDING
, 0);
1029 list_add_tail(&timer
->cb_entry
,
1030 &base
->cpu_base
->cb_pending
);
1035 __remove_hrtimer(timer
, base
,
1036 HRTIMER_STATE_CALLBACK
, 0);
1037 timer_stats_account_hrtimer(timer
);
1040 * Note: We clear the CALLBACK bit after
1041 * enqueue_hrtimer to avoid reprogramming of
1042 * the event hardware. This happens at the end
1043 * of this function anyway.
1045 if (timer
->function(timer
) != HRTIMER_NORESTART
) {
1046 BUG_ON(timer
->state
!= HRTIMER_STATE_CALLBACK
);
1047 enqueue_hrtimer(timer
, base
, 0);
1049 timer
->state
&= ~HRTIMER_STATE_CALLBACK
;
1051 spin_unlock(&cpu_base
->lock
);
1055 cpu_base
->expires_next
= expires_next
;
1057 /* Reprogramming necessary ? */
1058 if (expires_next
.tv64
!= KTIME_MAX
) {
1059 if (tick_program_event(expires_next
, 0))
1063 /* Raise softirq ? */
1065 raise_softirq(HRTIMER_SOFTIRQ
);
1068 static void run_hrtimer_softirq(struct softirq_action
*h
)
1070 struct hrtimer_cpu_base
*cpu_base
= &__get_cpu_var(hrtimer_bases
);
1072 spin_lock_irq(&cpu_base
->lock
);
1074 while (!list_empty(&cpu_base
->cb_pending
)) {
1075 enum hrtimer_restart (*fn
)(struct hrtimer
*);
1076 struct hrtimer
*timer
;
1079 timer
= list_entry(cpu_base
->cb_pending
.next
,
1080 struct hrtimer
, cb_entry
);
1082 timer_stats_account_hrtimer(timer
);
1084 fn
= timer
->function
;
1085 __remove_hrtimer(timer
, timer
->base
, HRTIMER_STATE_CALLBACK
, 0);
1086 spin_unlock_irq(&cpu_base
->lock
);
1088 restart
= fn(timer
);
1090 spin_lock_irq(&cpu_base
->lock
);
1092 timer
->state
&= ~HRTIMER_STATE_CALLBACK
;
1093 if (restart
== HRTIMER_RESTART
) {
1094 BUG_ON(hrtimer_active(timer
));
1096 * Enqueue the timer, allow reprogramming of the event
1099 enqueue_hrtimer(timer
, timer
->base
, 1);
1100 } else if (hrtimer_active(timer
)) {
1102 * If the timer was rearmed on another CPU, reprogram
1105 if (timer
->base
->first
== &timer
->node
)
1106 hrtimer_reprogram(timer
, timer
->base
);
1109 spin_unlock_irq(&cpu_base
->lock
);
1112 #endif /* CONFIG_HIGH_RES_TIMERS */
1115 * Expire the per base hrtimer-queue:
1117 static inline void run_hrtimer_queue(struct hrtimer_cpu_base
*cpu_base
,
1120 struct rb_node
*node
;
1121 struct hrtimer_clock_base
*base
= &cpu_base
->clock_base
[index
];
1126 if (base
->get_softirq_time
)
1127 base
->softirq_time
= base
->get_softirq_time();
1129 spin_lock_irq(&cpu_base
->lock
);
1131 while ((node
= base
->first
)) {
1132 struct hrtimer
*timer
;
1133 enum hrtimer_restart (*fn
)(struct hrtimer
*);
1136 timer
= rb_entry(node
, struct hrtimer
, node
);
1137 if (base
->softirq_time
.tv64
<= timer
->expires
.tv64
)
1140 #ifdef CONFIG_HIGH_RES_TIMERS
1141 WARN_ON_ONCE(timer
->cb_mode
== HRTIMER_CB_IRQSAFE_NO_SOFTIRQ
);
1143 timer_stats_account_hrtimer(timer
);
1145 fn
= timer
->function
;
1146 __remove_hrtimer(timer
, base
, HRTIMER_STATE_CALLBACK
, 0);
1147 spin_unlock_irq(&cpu_base
->lock
);
1149 restart
= fn(timer
);
1151 spin_lock_irq(&cpu_base
->lock
);
1153 timer
->state
&= ~HRTIMER_STATE_CALLBACK
;
1154 if (restart
!= HRTIMER_NORESTART
) {
1155 BUG_ON(hrtimer_active(timer
));
1156 enqueue_hrtimer(timer
, base
, 0);
1159 spin_unlock_irq(&cpu_base
->lock
);
1163 * Called from timer softirq every jiffy, expire hrtimers:
1165 * For HRT its the fall back code to run the softirq in the timer
1166 * softirq context in case the hrtimer initialization failed or has
1167 * not been done yet.
1169 void hrtimer_run_queues(void)
1171 struct hrtimer_cpu_base
*cpu_base
= &__get_cpu_var(hrtimer_bases
);
1174 if (hrtimer_hres_active())
1178 * This _is_ ugly: We have to check in the softirq context,
1179 * whether we can switch to highres and / or nohz mode. The
1180 * clocksource switch happens in the timer interrupt with
1181 * xtime_lock held. Notification from there only sets the
1182 * check bit in the tick_oneshot code, otherwise we might
1183 * deadlock vs. xtime_lock.
1185 if (tick_check_oneshot_change(!hrtimer_is_hres_enabled()))
1186 if (hrtimer_switch_to_hres())
1189 hrtimer_get_softirq_time(cpu_base
);
1191 for (i
= 0; i
< HRTIMER_MAX_CLOCK_BASES
; i
++)
1192 run_hrtimer_queue(cpu_base
, i
);
1196 * Sleep related functions:
1198 static enum hrtimer_restart
hrtimer_wakeup(struct hrtimer
*timer
)
1200 struct hrtimer_sleeper
*t
=
1201 container_of(timer
, struct hrtimer_sleeper
, timer
);
1202 struct task_struct
*task
= t
->task
;
1206 wake_up_process(task
);
1208 return HRTIMER_NORESTART
;
1211 void hrtimer_init_sleeper(struct hrtimer_sleeper
*sl
, struct task_struct
*task
)
1213 sl
->timer
.function
= hrtimer_wakeup
;
1215 #ifdef CONFIG_HIGH_RES_TIMERS
1216 sl
->timer
.cb_mode
= HRTIMER_CB_IRQSAFE_NO_RESTART
;
1220 static int __sched
do_nanosleep(struct hrtimer_sleeper
*t
, enum hrtimer_mode mode
)
1222 hrtimer_init_sleeper(t
, current
);
1225 set_current_state(TASK_INTERRUPTIBLE
);
1226 hrtimer_start(&t
->timer
, t
->timer
.expires
, mode
);
1228 if (likely(t
->task
))
1231 hrtimer_cancel(&t
->timer
);
1232 mode
= HRTIMER_MODE_ABS
;
1234 } while (t
->task
&& !signal_pending(current
));
1236 return t
->task
== NULL
;
1239 long __sched
hrtimer_nanosleep_restart(struct restart_block
*restart
)
1241 struct hrtimer_sleeper t
;
1242 struct timespec __user
*rmtp
;
1246 restart
->fn
= do_no_restart_syscall
;
1248 hrtimer_init(&t
.timer
, restart
->arg0
, HRTIMER_MODE_ABS
);
1249 t
.timer
.expires
.tv64
= ((u64
)restart
->arg3
<< 32) | (u64
) restart
->arg2
;
1251 if (do_nanosleep(&t
, HRTIMER_MODE_ABS
))
1254 rmtp
= (struct timespec __user
*) restart
->arg1
;
1256 time
= ktime_sub(t
.timer
.expires
, t
.timer
.base
->get_time());
1259 tu
= ktime_to_timespec(time
);
1260 if (copy_to_user(rmtp
, &tu
, sizeof(tu
)))
1264 restart
->fn
= hrtimer_nanosleep_restart
;
1266 /* The other values in restart are already filled in */
1267 return -ERESTART_RESTARTBLOCK
;
1270 long hrtimer_nanosleep(struct timespec
*rqtp
, struct timespec __user
*rmtp
,
1271 const enum hrtimer_mode mode
, const clockid_t clockid
)
1273 struct restart_block
*restart
;
1274 struct hrtimer_sleeper t
;
1278 hrtimer_init(&t
.timer
, clockid
, mode
);
1279 t
.timer
.expires
= timespec_to_ktime(*rqtp
);
1280 if (do_nanosleep(&t
, mode
))
1283 /* Absolute timers do not update the rmtp value and restart: */
1284 if (mode
== HRTIMER_MODE_ABS
)
1285 return -ERESTARTNOHAND
;
1288 rem
= ktime_sub(t
.timer
.expires
, t
.timer
.base
->get_time());
1291 tu
= ktime_to_timespec(rem
);
1292 if (copy_to_user(rmtp
, &tu
, sizeof(tu
)))
1296 restart
= ¤t_thread_info()->restart_block
;
1297 restart
->fn
= hrtimer_nanosleep_restart
;
1298 restart
->arg0
= (unsigned long) t
.timer
.base
->index
;
1299 restart
->arg1
= (unsigned long) rmtp
;
1300 restart
->arg2
= t
.timer
.expires
.tv64
& 0xFFFFFFFF;
1301 restart
->arg3
= t
.timer
.expires
.tv64
>> 32;
1303 return -ERESTART_RESTARTBLOCK
;
1307 sys_nanosleep(struct timespec __user
*rqtp
, struct timespec __user
*rmtp
)
1311 if (copy_from_user(&tu
, rqtp
, sizeof(tu
)))
1314 if (!timespec_valid(&tu
))
1317 return hrtimer_nanosleep(&tu
, rmtp
, HRTIMER_MODE_REL
, CLOCK_MONOTONIC
);
1321 * Functions related to boot-time initialization:
1323 static void __devinit
init_hrtimers_cpu(int cpu
)
1325 struct hrtimer_cpu_base
*cpu_base
= &per_cpu(hrtimer_bases
, cpu
);
1328 spin_lock_init(&cpu_base
->lock
);
1329 lockdep_set_class(&cpu_base
->lock
, &cpu_base
->lock_key
);
1331 for (i
= 0; i
< HRTIMER_MAX_CLOCK_BASES
; i
++)
1332 cpu_base
->clock_base
[i
].cpu_base
= cpu_base
;
1334 hrtimer_init_hres(cpu_base
);
1337 #ifdef CONFIG_HOTPLUG_CPU
1339 static void migrate_hrtimer_list(struct hrtimer_clock_base
*old_base
,
1340 struct hrtimer_clock_base
*new_base
)
1342 struct hrtimer
*timer
;
1343 struct rb_node
*node
;
1345 while ((node
= rb_first(&old_base
->active
))) {
1346 timer
= rb_entry(node
, struct hrtimer
, node
);
1347 BUG_ON(hrtimer_callback_running(timer
));
1348 __remove_hrtimer(timer
, old_base
, HRTIMER_STATE_INACTIVE
, 0);
1349 timer
->base
= new_base
;
1351 * Enqueue the timer. Allow reprogramming of the event device
1353 enqueue_hrtimer(timer
, new_base
, 1);
1357 static void migrate_hrtimers(int cpu
)
1359 struct hrtimer_cpu_base
*old_base
, *new_base
;
1362 BUG_ON(cpu_online(cpu
));
1363 old_base
= &per_cpu(hrtimer_bases
, cpu
);
1364 new_base
= &get_cpu_var(hrtimer_bases
);
1366 tick_cancel_sched_timer(cpu
);
1368 local_irq_disable();
1369 double_spin_lock(&new_base
->lock
, &old_base
->lock
,
1370 smp_processor_id() < cpu
);
1372 for (i
= 0; i
< HRTIMER_MAX_CLOCK_BASES
; i
++) {
1373 migrate_hrtimer_list(&old_base
->clock_base
[i
],
1374 &new_base
->clock_base
[i
]);
1377 double_spin_unlock(&new_base
->lock
, &old_base
->lock
,
1378 smp_processor_id() < cpu
);
1380 put_cpu_var(hrtimer_bases
);
1382 #endif /* CONFIG_HOTPLUG_CPU */
1384 static int __cpuinit
hrtimer_cpu_notify(struct notifier_block
*self
,
1385 unsigned long action
, void *hcpu
)
1387 long cpu
= (long)hcpu
;
1391 case CPU_UP_PREPARE
:
1392 init_hrtimers_cpu(cpu
);
1395 #ifdef CONFIG_HOTPLUG_CPU
1397 clockevents_notify(CLOCK_EVT_NOTIFY_CPU_DEAD
, &cpu
);
1398 migrate_hrtimers(cpu
);
1409 static struct notifier_block __cpuinitdata hrtimers_nb
= {
1410 .notifier_call
= hrtimer_cpu_notify
,
1413 void __init
hrtimers_init(void)
1415 hrtimer_cpu_notify(&hrtimers_nb
, (unsigned long)CPU_UP_PREPARE
,
1416 (void *)(long)smp_processor_id());
1417 register_cpu_notifier(&hrtimers_nb
);
1418 #ifdef CONFIG_HIGH_RES_TIMERS
1419 open_softirq(HRTIMER_SOFTIRQ
, run_hrtimer_softirq
, NULL
);