4 * Kernel internal timers, basic process system calls
6 * Copyright (C) 1991, 1992 Linus Torvalds
8 * 1997-01-28 Modified by Finn Arne Gangstad to make timers scale better.
10 * 1997-09-10 Updated NTP code according to technical memorandum Jan '96
11 * "A Kernel Model for Precision Timekeeping" by Dave Mills
12 * 1998-12-24 Fixed a xtime SMP race (we need the xtime_lock rw spinlock to
13 * serialize accesses to xtime/lost_ticks).
14 * Copyright (C) 1998 Andrea Arcangeli
15 * 1999-03-10 Improved NTP compatibility by Ulrich Windl
16 * 2002-05-31 Move sys_sysinfo here and make its locking sane, Robert Love
17 * 2000-10-05 Implemented scalable SMP per-CPU timer handling.
18 * Copyright (C) 2000, 2001, 2002 Ingo Molnar
19 * Designed by David S. Miller, Alexey Kuznetsov and Ingo Molnar
22 #include <linux/kernel_stat.h>
23 #include <linux/module.h>
24 #include <linux/interrupt.h>
25 #include <linux/percpu.h>
26 #include <linux/init.h>
28 #include <linux/swap.h>
29 #include <linux/pid_namespace.h>
30 #include <linux/notifier.h>
31 #include <linux/thread_info.h>
32 #include <linux/time.h>
33 #include <linux/jiffies.h>
34 #include <linux/posix-timers.h>
35 #include <linux/cpu.h>
36 #include <linux/syscalls.h>
37 #include <linux/delay.h>
38 #include <linux/tick.h>
39 #include <linux/kallsyms.h>
41 #include <asm/uaccess.h>
42 #include <asm/unistd.h>
43 #include <asm/div64.h>
44 #include <asm/timex.h>
47 u64 jiffies_64 __cacheline_aligned_in_smp
= INITIAL_JIFFIES
;
49 EXPORT_SYMBOL(jiffies_64
);
52 * per-CPU timer vector definitions:
54 #define TVN_BITS (CONFIG_BASE_SMALL ? 4 : 6)
55 #define TVR_BITS (CONFIG_BASE_SMALL ? 6 : 8)
56 #define TVN_SIZE (1 << TVN_BITS)
57 #define TVR_SIZE (1 << TVR_BITS)
58 #define TVN_MASK (TVN_SIZE - 1)
59 #define TVR_MASK (TVR_SIZE - 1)
62 struct list_head vec
[TVN_SIZE
];
66 struct list_head vec
[TVR_SIZE
];
71 struct timer_list
*running_timer
;
72 unsigned long timer_jiffies
;
78 } ____cacheline_aligned
;
80 struct tvec_base boot_tvec_bases
;
81 EXPORT_SYMBOL(boot_tvec_bases
);
82 static DEFINE_PER_CPU(struct tvec_base
*, tvec_bases
) = &boot_tvec_bases
;
85 * Note that all tvec_bases are 2 byte aligned and lower bit of
86 * base in timer_list is guaranteed to be zero. Use the LSB for
87 * the new flag to indicate whether the timer is deferrable
89 #define TBASE_DEFERRABLE_FLAG (0x1)
91 /* Functions below help us manage 'deferrable' flag */
92 static inline unsigned int tbase_get_deferrable(struct tvec_base
*base
)
94 return ((unsigned int)(unsigned long)base
& TBASE_DEFERRABLE_FLAG
);
97 static inline struct tvec_base
*tbase_get_base(struct tvec_base
*base
)
99 return ((struct tvec_base
*)((unsigned long)base
& ~TBASE_DEFERRABLE_FLAG
));
102 static inline void timer_set_deferrable(struct timer_list
*timer
)
104 timer
->base
= ((struct tvec_base
*)((unsigned long)(timer
->base
) |
105 TBASE_DEFERRABLE_FLAG
));
109 timer_set_base(struct timer_list
*timer
, struct tvec_base
*new_base
)
111 timer
->base
= (struct tvec_base
*)((unsigned long)(new_base
) |
112 tbase_get_deferrable(timer
->base
));
115 static unsigned long round_jiffies_common(unsigned long j
, int cpu
,
119 unsigned long original
= j
;
122 * We don't want all cpus firing their timers at once hitting the
123 * same lock or cachelines, so we skew each extra cpu with an extra
124 * 3 jiffies. This 3 jiffies came originally from the mm/ code which
126 * The skew is done by adding 3*cpunr, then round, then subtract this
127 * extra offset again.
134 * If the target jiffie is just after a whole second (which can happen
135 * due to delays of the timer irq, long irq off times etc etc) then
136 * we should round down to the whole second, not up. Use 1/4th second
137 * as cutoff for this rounding as an extreme upper bound for this.
138 * But never round down if @force_up is set.
140 if (rem
< HZ
/4 && !force_up
) /* round down */
145 /* now that we have rounded, subtract the extra skew again */
148 if (j
<= jiffies
) /* rounding ate our timeout entirely; */
154 * __round_jiffies - function to round jiffies to a full second
155 * @j: the time in (absolute) jiffies that should be rounded
156 * @cpu: the processor number on which the timeout will happen
158 * __round_jiffies() rounds an absolute time in the future (in jiffies)
159 * up or down to (approximately) full seconds. This is useful for timers
160 * for which the exact time they fire does not matter too much, as long as
161 * they fire approximately every X seconds.
163 * By rounding these timers to whole seconds, all such timers will fire
164 * at the same time, rather than at various times spread out. The goal
165 * of this is to have the CPU wake up less, which saves power.
167 * The exact rounding is skewed for each processor to avoid all
168 * processors firing at the exact same time, which could lead
169 * to lock contention or spurious cache line bouncing.
171 * The return value is the rounded version of the @j parameter.
173 unsigned long __round_jiffies(unsigned long j
, int cpu
)
175 return round_jiffies_common(j
, cpu
, false);
177 EXPORT_SYMBOL_GPL(__round_jiffies
);
180 * __round_jiffies_relative - function to round jiffies to a full second
181 * @j: the time in (relative) jiffies that should be rounded
182 * @cpu: the processor number on which the timeout will happen
184 * __round_jiffies_relative() rounds a time delta in the future (in jiffies)
185 * up or down to (approximately) full seconds. This is useful for timers
186 * for which the exact time they fire does not matter too much, as long as
187 * they fire approximately every X seconds.
189 * By rounding these timers to whole seconds, all such timers will fire
190 * at the same time, rather than at various times spread out. The goal
191 * of this is to have the CPU wake up less, which saves power.
193 * The exact rounding is skewed for each processor to avoid all
194 * processors firing at the exact same time, which could lead
195 * to lock contention or spurious cache line bouncing.
197 * The return value is the rounded version of the @j parameter.
199 unsigned long __round_jiffies_relative(unsigned long j
, int cpu
)
201 unsigned long j0
= jiffies
;
203 /* Use j0 because jiffies might change while we run */
204 return round_jiffies_common(j
+ j0
, cpu
, false) - j0
;
206 EXPORT_SYMBOL_GPL(__round_jiffies_relative
);
209 * round_jiffies - function to round jiffies to a full second
210 * @j: the time in (absolute) jiffies that should be rounded
212 * round_jiffies() rounds an absolute time in the future (in jiffies)
213 * up or down to (approximately) full seconds. This is useful for timers
214 * for which the exact time they fire does not matter too much, as long as
215 * they fire approximately every X seconds.
217 * By rounding these timers to whole seconds, all such timers will fire
218 * at the same time, rather than at various times spread out. The goal
219 * of this is to have the CPU wake up less, which saves power.
221 * The return value is the rounded version of the @j parameter.
223 unsigned long round_jiffies(unsigned long j
)
225 return round_jiffies_common(j
, raw_smp_processor_id(), false);
227 EXPORT_SYMBOL_GPL(round_jiffies
);
230 * round_jiffies_relative - function to round jiffies to a full second
231 * @j: the time in (relative) jiffies that should be rounded
233 * round_jiffies_relative() rounds a time delta in the future (in jiffies)
234 * up or down to (approximately) full seconds. This is useful for timers
235 * for which the exact time they fire does not matter too much, as long as
236 * they fire approximately every X seconds.
238 * By rounding these timers to whole seconds, all such timers will fire
239 * at the same time, rather than at various times spread out. The goal
240 * of this is to have the CPU wake up less, which saves power.
242 * The return value is the rounded version of the @j parameter.
244 unsigned long round_jiffies_relative(unsigned long j
)
246 return __round_jiffies_relative(j
, raw_smp_processor_id());
248 EXPORT_SYMBOL_GPL(round_jiffies_relative
);
251 * __round_jiffies_up - function to round jiffies up to a full second
252 * @j: the time in (absolute) jiffies that should be rounded
253 * @cpu: the processor number on which the timeout will happen
255 * This is the same as __round_jiffies() except that it will never
256 * round down. This is useful for timeouts for which the exact time
257 * of firing does not matter too much, as long as they don't fire too
260 unsigned long __round_jiffies_up(unsigned long j
, int cpu
)
262 return round_jiffies_common(j
, cpu
, true);
264 EXPORT_SYMBOL_GPL(__round_jiffies_up
);
267 * __round_jiffies_up_relative - function to round jiffies up to a full second
268 * @j: the time in (relative) jiffies that should be rounded
269 * @cpu: the processor number on which the timeout will happen
271 * This is the same as __round_jiffies_relative() except that it will never
272 * round down. This is useful for timeouts for which the exact time
273 * of firing does not matter too much, as long as they don't fire too
276 unsigned long __round_jiffies_up_relative(unsigned long j
, int cpu
)
278 unsigned long j0
= jiffies
;
280 /* Use j0 because jiffies might change while we run */
281 return round_jiffies_common(j
+ j0
, cpu
, true) - j0
;
283 EXPORT_SYMBOL_GPL(__round_jiffies_up_relative
);
286 * round_jiffies_up - function to round jiffies up to a full second
287 * @j: the time in (absolute) jiffies that should be rounded
289 * This is the same as round_jiffies() except that it will never
290 * round down. This is useful for timeouts for which the exact time
291 * of firing does not matter too much, as long as they don't fire too
294 unsigned long round_jiffies_up(unsigned long j
)
296 return round_jiffies_common(j
, raw_smp_processor_id(), true);
298 EXPORT_SYMBOL_GPL(round_jiffies_up
);
301 * round_jiffies_up_relative - function to round jiffies up to a full second
302 * @j: the time in (relative) jiffies that should be rounded
304 * This is the same as round_jiffies_relative() except that it will never
305 * round down. This is useful for timeouts for which the exact time
306 * of firing does not matter too much, as long as they don't fire too
309 unsigned long round_jiffies_up_relative(unsigned long j
)
311 return __round_jiffies_up_relative(j
, raw_smp_processor_id());
313 EXPORT_SYMBOL_GPL(round_jiffies_up_relative
);
316 static inline void set_running_timer(struct tvec_base
*base
,
317 struct timer_list
*timer
)
320 base
->running_timer
= timer
;
324 static void internal_add_timer(struct tvec_base
*base
, struct timer_list
*timer
)
326 unsigned long expires
= timer
->expires
;
327 unsigned long idx
= expires
- base
->timer_jiffies
;
328 struct list_head
*vec
;
330 if (idx
< TVR_SIZE
) {
331 int i
= expires
& TVR_MASK
;
332 vec
= base
->tv1
.vec
+ i
;
333 } else if (idx
< 1 << (TVR_BITS
+ TVN_BITS
)) {
334 int i
= (expires
>> TVR_BITS
) & TVN_MASK
;
335 vec
= base
->tv2
.vec
+ i
;
336 } else if (idx
< 1 << (TVR_BITS
+ 2 * TVN_BITS
)) {
337 int i
= (expires
>> (TVR_BITS
+ TVN_BITS
)) & TVN_MASK
;
338 vec
= base
->tv3
.vec
+ i
;
339 } else if (idx
< 1 << (TVR_BITS
+ 3 * TVN_BITS
)) {
340 int i
= (expires
>> (TVR_BITS
+ 2 * TVN_BITS
)) & TVN_MASK
;
341 vec
= base
->tv4
.vec
+ i
;
342 } else if ((signed long) idx
< 0) {
344 * Can happen if you add a timer with expires == jiffies,
345 * or you set a timer to go off in the past
347 vec
= base
->tv1
.vec
+ (base
->timer_jiffies
& TVR_MASK
);
350 /* If the timeout is larger than 0xffffffff on 64-bit
351 * architectures then we use the maximum timeout:
353 if (idx
> 0xffffffffUL
) {
355 expires
= idx
+ base
->timer_jiffies
;
357 i
= (expires
>> (TVR_BITS
+ 3 * TVN_BITS
)) & TVN_MASK
;
358 vec
= base
->tv5
.vec
+ i
;
363 list_add_tail(&timer
->entry
, vec
);
366 #ifdef CONFIG_TIMER_STATS
367 void __timer_stats_timer_set_start_info(struct timer_list
*timer
, void *addr
)
369 if (timer
->start_site
)
372 timer
->start_site
= addr
;
373 memcpy(timer
->start_comm
, current
->comm
, TASK_COMM_LEN
);
374 timer
->start_pid
= current
->pid
;
377 static void timer_stats_account_timer(struct timer_list
*timer
)
379 unsigned int flag
= 0;
381 if (unlikely(tbase_get_deferrable(timer
->base
)))
382 flag
|= TIMER_STATS_FLAG_DEFERRABLE
;
384 timer_stats_update_stats(timer
, timer
->start_pid
, timer
->start_site
,
385 timer
->function
, timer
->start_comm
, flag
);
389 static void timer_stats_account_timer(struct timer_list
*timer
) {}
392 #ifdef CONFIG_DEBUG_OBJECTS_TIMERS
394 static struct debug_obj_descr timer_debug_descr
;
397 * fixup_init is called when:
398 * - an active object is initialized
400 static int timer_fixup_init(void *addr
, enum debug_obj_state state
)
402 struct timer_list
*timer
= addr
;
405 case ODEBUG_STATE_ACTIVE
:
406 del_timer_sync(timer
);
407 debug_object_init(timer
, &timer_debug_descr
);
415 * fixup_activate is called when:
416 * - an active object is activated
417 * - an unknown object is activated (might be a statically initialized object)
419 static int timer_fixup_activate(void *addr
, enum debug_obj_state state
)
421 struct timer_list
*timer
= addr
;
425 case ODEBUG_STATE_NOTAVAILABLE
:
427 * This is not really a fixup. The timer was
428 * statically initialized. We just make sure that it
429 * is tracked in the object tracker.
431 if (timer
->entry
.next
== NULL
&&
432 timer
->entry
.prev
== TIMER_ENTRY_STATIC
) {
433 debug_object_init(timer
, &timer_debug_descr
);
434 debug_object_activate(timer
, &timer_debug_descr
);
441 case ODEBUG_STATE_ACTIVE
:
450 * fixup_free is called when:
451 * - an active object is freed
453 static int timer_fixup_free(void *addr
, enum debug_obj_state state
)
455 struct timer_list
*timer
= addr
;
458 case ODEBUG_STATE_ACTIVE
:
459 del_timer_sync(timer
);
460 debug_object_free(timer
, &timer_debug_descr
);
467 static struct debug_obj_descr timer_debug_descr
= {
468 .name
= "timer_list",
469 .fixup_init
= timer_fixup_init
,
470 .fixup_activate
= timer_fixup_activate
,
471 .fixup_free
= timer_fixup_free
,
474 static inline void debug_timer_init(struct timer_list
*timer
)
476 debug_object_init(timer
, &timer_debug_descr
);
479 static inline void debug_timer_activate(struct timer_list
*timer
)
481 debug_object_activate(timer
, &timer_debug_descr
);
484 static inline void debug_timer_deactivate(struct timer_list
*timer
)
486 debug_object_deactivate(timer
, &timer_debug_descr
);
489 static inline void debug_timer_free(struct timer_list
*timer
)
491 debug_object_free(timer
, &timer_debug_descr
);
494 static void __init_timer(struct timer_list
*timer
,
496 struct lock_class_key
*key
);
498 void init_timer_on_stack_key(struct timer_list
*timer
,
500 struct lock_class_key
*key
)
502 debug_object_init_on_stack(timer
, &timer_debug_descr
);
503 __init_timer(timer
, name
, key
);
505 EXPORT_SYMBOL_GPL(init_timer_on_stack_key
);
507 void destroy_timer_on_stack(struct timer_list
*timer
)
509 debug_object_free(timer
, &timer_debug_descr
);
511 EXPORT_SYMBOL_GPL(destroy_timer_on_stack
);
514 static inline void debug_timer_init(struct timer_list
*timer
) { }
515 static inline void debug_timer_activate(struct timer_list
*timer
) { }
516 static inline void debug_timer_deactivate(struct timer_list
*timer
) { }
519 static void __init_timer(struct timer_list
*timer
,
521 struct lock_class_key
*key
)
523 timer
->entry
.next
= NULL
;
524 timer
->base
= __raw_get_cpu_var(tvec_bases
);
525 #ifdef CONFIG_TIMER_STATS
526 timer
->start_site
= NULL
;
527 timer
->start_pid
= -1;
528 memset(timer
->start_comm
, 0, TASK_COMM_LEN
);
530 lockdep_init_map(&timer
->lockdep_map
, name
, key
, 0);
534 * init_timer - initialize a timer.
535 * @timer: the timer to be initialized
537 * init_timer() must be done to a timer prior calling *any* of the
538 * other timer functions.
540 void init_timer_key(struct timer_list
*timer
,
542 struct lock_class_key
*key
)
544 debug_timer_init(timer
);
545 __init_timer(timer
, name
, key
);
547 EXPORT_SYMBOL(init_timer_key
);
549 void init_timer_deferrable_key(struct timer_list
*timer
,
551 struct lock_class_key
*key
)
553 init_timer_key(timer
, name
, key
);
554 timer_set_deferrable(timer
);
556 EXPORT_SYMBOL(init_timer_deferrable_key
);
558 static inline void detach_timer(struct timer_list
*timer
,
561 struct list_head
*entry
= &timer
->entry
;
563 debug_timer_deactivate(timer
);
565 __list_del(entry
->prev
, entry
->next
);
568 entry
->prev
= LIST_POISON2
;
572 * We are using hashed locking: holding per_cpu(tvec_bases).lock
573 * means that all timers which are tied to this base via timer->base are
574 * locked, and the base itself is locked too.
576 * So __run_timers/migrate_timers can safely modify all timers which could
577 * be found on ->tvX lists.
579 * When the timer's base is locked, and the timer removed from list, it is
580 * possible to set timer->base = NULL and drop the lock: the timer remains
583 static struct tvec_base
*lock_timer_base(struct timer_list
*timer
,
584 unsigned long *flags
)
585 __acquires(timer
->base
->lock
)
587 struct tvec_base
*base
;
590 struct tvec_base
*prelock_base
= timer
->base
;
591 base
= tbase_get_base(prelock_base
);
592 if (likely(base
!= NULL
)) {
593 spin_lock_irqsave(&base
->lock
, *flags
);
594 if (likely(prelock_base
== timer
->base
))
596 /* The timer has migrated to another CPU */
597 spin_unlock_irqrestore(&base
->lock
, *flags
);
604 __mod_timer(struct timer_list
*timer
, unsigned long expires
, bool pending_only
)
606 struct tvec_base
*base
, *new_base
;
612 timer_stats_timer_set_start_info(timer
);
613 BUG_ON(!timer
->function
);
615 base
= lock_timer_base(timer
, &flags
);
617 if (timer_pending(timer
)) {
618 detach_timer(timer
, 0);
625 debug_timer_activate(timer
);
627 new_base
= __get_cpu_var(tvec_bases
);
629 if (base
!= new_base
) {
631 * We are trying to schedule the timer on the local CPU.
632 * However we can't change timer's base while it is running,
633 * otherwise del_timer_sync() can't detect that the timer's
634 * handler yet has not finished. This also guarantees that
635 * the timer is serialized wrt itself.
637 if (likely(base
->running_timer
!= timer
)) {
638 /* See the comment in lock_timer_base() */
639 timer_set_base(timer
, NULL
);
640 spin_unlock(&base
->lock
);
642 spin_lock(&base
->lock
);
643 timer_set_base(timer
, base
);
647 timer
->expires
= expires
;
648 internal_add_timer(base
, timer
);
651 spin_unlock_irqrestore(&base
->lock
, flags
);
657 * mod_timer_pending - modify a pending timer's timeout
658 * @timer: the pending timer to be modified
659 * @expires: new timeout in jiffies
661 * mod_timer_pending() is the same for pending timers as mod_timer(),
662 * but will not re-activate and modify already deleted timers.
664 * It is useful for unserialized use of timers.
666 int mod_timer_pending(struct timer_list
*timer
, unsigned long expires
)
668 return __mod_timer(timer
, expires
, true);
670 EXPORT_SYMBOL(mod_timer_pending
);
673 * mod_timer - modify a timer's timeout
674 * @timer: the timer to be modified
675 * @expires: new timeout in jiffies
677 * mod_timer() is a more efficient way to update the expire field of an
678 * active timer (if the timer is inactive it will be activated)
680 * mod_timer(timer, expires) is equivalent to:
682 * del_timer(timer); timer->expires = expires; add_timer(timer);
684 * Note that if there are multiple unserialized concurrent users of the
685 * same timer, then mod_timer() is the only safe way to modify the timeout,
686 * since add_timer() cannot modify an already running timer.
688 * The function returns whether it has modified a pending timer or not.
689 * (ie. mod_timer() of an inactive timer returns 0, mod_timer() of an
690 * active timer returns 1.)
692 int mod_timer(struct timer_list
*timer
, unsigned long expires
)
695 * This is a common optimization triggered by the
696 * networking code - if the timer is re-modified
697 * to be the same thing then just return:
699 if (timer
->expires
== expires
&& timer_pending(timer
))
702 return __mod_timer(timer
, expires
, false);
704 EXPORT_SYMBOL(mod_timer
);
707 * add_timer - start a timer
708 * @timer: the timer to be added
710 * The kernel will do a ->function(->data) callback from the
711 * timer interrupt at the ->expires point in the future. The
712 * current time is 'jiffies'.
714 * The timer's ->expires, ->function (and if the handler uses it, ->data)
715 * fields must be set prior calling this function.
717 * Timers with an ->expires field in the past will be executed in the next
720 void add_timer(struct timer_list
*timer
)
722 BUG_ON(timer_pending(timer
));
723 mod_timer(timer
, timer
->expires
);
725 EXPORT_SYMBOL(add_timer
);
728 * add_timer_on - start a timer on a particular CPU
729 * @timer: the timer to be added
730 * @cpu: the CPU to start it on
732 * This is not very scalable on SMP. Double adds are not possible.
734 void add_timer_on(struct timer_list
*timer
, int cpu
)
736 struct tvec_base
*base
= per_cpu(tvec_bases
, cpu
);
739 timer_stats_timer_set_start_info(timer
);
740 BUG_ON(timer_pending(timer
) || !timer
->function
);
741 spin_lock_irqsave(&base
->lock
, flags
);
742 timer_set_base(timer
, base
);
743 debug_timer_activate(timer
);
744 internal_add_timer(base
, timer
);
746 * Check whether the other CPU is idle and needs to be
747 * triggered to reevaluate the timer wheel when nohz is
748 * active. We are protected against the other CPU fiddling
749 * with the timer by holding the timer base lock. This also
750 * makes sure that a CPU on the way to idle can not evaluate
753 wake_up_idle_cpu(cpu
);
754 spin_unlock_irqrestore(&base
->lock
, flags
);
758 * del_timer - deactive a timer.
759 * @timer: the timer to be deactivated
761 * del_timer() deactivates a timer - this works on both active and inactive
764 * The function returns whether it has deactivated a pending timer or not.
765 * (ie. del_timer() of an inactive timer returns 0, del_timer() of an
766 * active timer returns 1.)
768 int del_timer(struct timer_list
*timer
)
770 struct tvec_base
*base
;
774 timer_stats_timer_clear_start_info(timer
);
775 if (timer_pending(timer
)) {
776 base
= lock_timer_base(timer
, &flags
);
777 if (timer_pending(timer
)) {
778 detach_timer(timer
, 1);
781 spin_unlock_irqrestore(&base
->lock
, flags
);
786 EXPORT_SYMBOL(del_timer
);
790 * try_to_del_timer_sync - Try to deactivate a timer
791 * @timer: timer do del
793 * This function tries to deactivate a timer. Upon successful (ret >= 0)
794 * exit the timer is not queued and the handler is not running on any CPU.
796 * It must not be called from interrupt contexts.
798 int try_to_del_timer_sync(struct timer_list
*timer
)
800 struct tvec_base
*base
;
804 base
= lock_timer_base(timer
, &flags
);
806 if (base
->running_timer
== timer
)
810 if (timer_pending(timer
)) {
811 detach_timer(timer
, 1);
815 spin_unlock_irqrestore(&base
->lock
, flags
);
819 EXPORT_SYMBOL(try_to_del_timer_sync
);
822 * del_timer_sync - deactivate a timer and wait for the handler to finish.
823 * @timer: the timer to be deactivated
825 * This function only differs from del_timer() on SMP: besides deactivating
826 * the timer it also makes sure the handler has finished executing on other
829 * Synchronization rules: Callers must prevent restarting of the timer,
830 * otherwise this function is meaningless. It must not be called from
831 * interrupt contexts. The caller must not hold locks which would prevent
832 * completion of the timer's handler. The timer's handler must not call
833 * add_timer_on(). Upon exit the timer is not queued and the handler is
834 * not running on any CPU.
836 * The function returns whether it has deactivated a pending timer or not.
838 int del_timer_sync(struct timer_list
*timer
)
840 #ifdef CONFIG_LOCKDEP
843 local_irq_save(flags
);
844 lock_map_acquire(&timer
->lockdep_map
);
845 lock_map_release(&timer
->lockdep_map
);
846 local_irq_restore(flags
);
850 int ret
= try_to_del_timer_sync(timer
);
856 EXPORT_SYMBOL(del_timer_sync
);
859 static int cascade(struct tvec_base
*base
, struct tvec
*tv
, int index
)
861 /* cascade all the timers from tv up one level */
862 struct timer_list
*timer
, *tmp
;
863 struct list_head tv_list
;
865 list_replace_init(tv
->vec
+ index
, &tv_list
);
868 * We are removing _all_ timers from the list, so we
869 * don't have to detach them individually.
871 list_for_each_entry_safe(timer
, tmp
, &tv_list
, entry
) {
872 BUG_ON(tbase_get_base(timer
->base
) != base
);
873 internal_add_timer(base
, timer
);
879 #define INDEX(N) ((base->timer_jiffies >> (TVR_BITS + (N) * TVN_BITS)) & TVN_MASK)
882 * __run_timers - run all expired timers (if any) on this CPU.
883 * @base: the timer vector to be processed.
885 * This function cascades all vectors and executes all expired timer
888 static inline void __run_timers(struct tvec_base
*base
)
890 struct timer_list
*timer
;
892 spin_lock_irq(&base
->lock
);
893 while (time_after_eq(jiffies
, base
->timer_jiffies
)) {
894 struct list_head work_list
;
895 struct list_head
*head
= &work_list
;
896 int index
= base
->timer_jiffies
& TVR_MASK
;
902 (!cascade(base
, &base
->tv2
, INDEX(0))) &&
903 (!cascade(base
, &base
->tv3
, INDEX(1))) &&
904 !cascade(base
, &base
->tv4
, INDEX(2)))
905 cascade(base
, &base
->tv5
, INDEX(3));
906 ++base
->timer_jiffies
;
907 list_replace_init(base
->tv1
.vec
+ index
, &work_list
);
908 while (!list_empty(head
)) {
909 void (*fn
)(unsigned long);
912 timer
= list_first_entry(head
, struct timer_list
,entry
);
913 fn
= timer
->function
;
916 timer_stats_account_timer(timer
);
918 set_running_timer(base
, timer
);
919 detach_timer(timer
, 1);
921 spin_unlock_irq(&base
->lock
);
923 int preempt_count
= preempt_count();
925 #ifdef CONFIG_LOCKDEP
927 * It is permissible to free the timer from
928 * inside the function that is called from
929 * it, this we need to take into account for
930 * lockdep too. To avoid bogus "held lock
931 * freed" warnings as well as problems when
932 * looking into timer->lockdep_map, make a
933 * copy and use that here.
935 struct lockdep_map lockdep_map
=
939 * Couple the lock chain with the lock chain at
940 * del_timer_sync() by acquiring the lock_map
941 * around the fn() call here and in
944 lock_map_acquire(&lockdep_map
);
948 lock_map_release(&lockdep_map
);
950 if (preempt_count
!= preempt_count()) {
951 printk(KERN_ERR
"huh, entered %p "
952 "with preempt_count %08x, exited"
959 spin_lock_irq(&base
->lock
);
962 set_running_timer(base
, NULL
);
963 spin_unlock_irq(&base
->lock
);
968 * Find out when the next timer event is due to happen. This
969 * is used on S/390 to stop all activity when a cpus is idle.
970 * This functions needs to be called disabled.
972 static unsigned long __next_timer_interrupt(struct tvec_base
*base
)
974 unsigned long timer_jiffies
= base
->timer_jiffies
;
975 unsigned long expires
= timer_jiffies
+ NEXT_TIMER_MAX_DELTA
;
976 int index
, slot
, array
, found
= 0;
977 struct timer_list
*nte
;
978 struct tvec
*varray
[4];
980 /* Look for timer events in tv1. */
981 index
= slot
= timer_jiffies
& TVR_MASK
;
983 list_for_each_entry(nte
, base
->tv1
.vec
+ slot
, entry
) {
984 if (tbase_get_deferrable(nte
->base
))
988 expires
= nte
->expires
;
989 /* Look at the cascade bucket(s)? */
990 if (!index
|| slot
< index
)
994 slot
= (slot
+ 1) & TVR_MASK
;
995 } while (slot
!= index
);
998 /* Calculate the next cascade event */
1000 timer_jiffies
+= TVR_SIZE
- index
;
1001 timer_jiffies
>>= TVR_BITS
;
1003 /* Check tv2-tv5. */
1004 varray
[0] = &base
->tv2
;
1005 varray
[1] = &base
->tv3
;
1006 varray
[2] = &base
->tv4
;
1007 varray
[3] = &base
->tv5
;
1009 for (array
= 0; array
< 4; array
++) {
1010 struct tvec
*varp
= varray
[array
];
1012 index
= slot
= timer_jiffies
& TVN_MASK
;
1014 list_for_each_entry(nte
, varp
->vec
+ slot
, entry
) {
1016 if (time_before(nte
->expires
, expires
))
1017 expires
= nte
->expires
;
1020 * Do we still search for the first timer or are
1021 * we looking up the cascade buckets ?
1024 /* Look at the cascade bucket(s)? */
1025 if (!index
|| slot
< index
)
1029 slot
= (slot
+ 1) & TVN_MASK
;
1030 } while (slot
!= index
);
1033 timer_jiffies
+= TVN_SIZE
- index
;
1034 timer_jiffies
>>= TVN_BITS
;
1040 * Check, if the next hrtimer event is before the next timer wheel
1043 static unsigned long cmp_next_hrtimer_event(unsigned long now
,
1044 unsigned long expires
)
1046 ktime_t hr_delta
= hrtimer_get_next_event();
1047 struct timespec tsdelta
;
1048 unsigned long delta
;
1050 if (hr_delta
.tv64
== KTIME_MAX
)
1054 * Expired timer available, let it expire in the next tick
1056 if (hr_delta
.tv64
<= 0)
1059 tsdelta
= ktime_to_timespec(hr_delta
);
1060 delta
= timespec_to_jiffies(&tsdelta
);
1063 * Limit the delta to the max value, which is checked in
1064 * tick_nohz_stop_sched_tick():
1066 if (delta
> NEXT_TIMER_MAX_DELTA
)
1067 delta
= NEXT_TIMER_MAX_DELTA
;
1070 * Take rounding errors in to account and make sure, that it
1071 * expires in the next tick. Otherwise we go into an endless
1072 * ping pong due to tick_nohz_stop_sched_tick() retriggering
1078 if (time_before(now
, expires
))
1084 * get_next_timer_interrupt - return the jiffy of the next pending timer
1085 * @now: current time (in jiffies)
1087 unsigned long get_next_timer_interrupt(unsigned long now
)
1089 struct tvec_base
*base
= __get_cpu_var(tvec_bases
);
1090 unsigned long expires
;
1092 spin_lock(&base
->lock
);
1093 expires
= __next_timer_interrupt(base
);
1094 spin_unlock(&base
->lock
);
1096 if (time_before_eq(expires
, now
))
1099 return cmp_next_hrtimer_event(now
, expires
);
1104 * Called from the timer interrupt handler to charge one tick to the current
1105 * process. user_tick is 1 if the tick is user time, 0 for system.
1107 void update_process_times(int user_tick
)
1109 struct task_struct
*p
= current
;
1110 int cpu
= smp_processor_id();
1112 /* Note: this timer irq context must be accounted for as well. */
1113 account_process_tick(p
, user_tick
);
1115 if (rcu_pending(cpu
))
1116 rcu_check_callbacks(cpu
, user_tick
);
1119 run_posix_cpu_timers(p
);
1123 * Nr of active tasks - counted in fixed-point numbers
1125 static unsigned long count_active_tasks(void)
1127 return nr_active() * FIXED_1
;
1131 * Hmm.. Changed this, as the GNU make sources (load.c) seems to
1132 * imply that avenrun[] is the standard name for this kind of thing.
1133 * Nothing else seems to be standardized: the fractional size etc
1134 * all seem to differ on different machines.
1136 * Requires xtime_lock to access.
1138 unsigned long avenrun
[3];
1140 EXPORT_SYMBOL(avenrun
);
1143 * calc_load - given tick count, update the avenrun load estimates.
1144 * This is called while holding a write_lock on xtime_lock.
1146 static inline void calc_load(unsigned long ticks
)
1148 unsigned long active_tasks
; /* fixed-point */
1149 static int count
= LOAD_FREQ
;
1152 if (unlikely(count
< 0)) {
1153 active_tasks
= count_active_tasks();
1155 CALC_LOAD(avenrun
[0], EXP_1
, active_tasks
);
1156 CALC_LOAD(avenrun
[1], EXP_5
, active_tasks
);
1157 CALC_LOAD(avenrun
[2], EXP_15
, active_tasks
);
1159 } while (count
< 0);
1164 * This function runs timers and the timer-tq in bottom half context.
1166 static void run_timer_softirq(struct softirq_action
*h
)
1168 struct tvec_base
*base
= __get_cpu_var(tvec_bases
);
1170 hrtimer_run_pending();
1172 if (time_after_eq(jiffies
, base
->timer_jiffies
))
1177 * Called by the local, per-CPU timer interrupt on SMP.
1179 void run_local_timers(void)
1181 hrtimer_run_queues();
1182 raise_softirq(TIMER_SOFTIRQ
);
1187 * Called by the timer interrupt. xtime_lock must already be taken
1190 static inline void update_times(unsigned long ticks
)
1197 * The 64-bit jiffies value is not atomic - you MUST NOT read it
1198 * without sampling the sequence number in xtime_lock.
1199 * jiffies is defined in the linker script...
1202 void do_timer(unsigned long ticks
)
1204 jiffies_64
+= ticks
;
1205 update_times(ticks
);
1208 #ifdef __ARCH_WANT_SYS_ALARM
1211 * For backwards compatibility? This can be done in libc so Alpha
1212 * and all newer ports shouldn't need it.
1214 SYSCALL_DEFINE1(alarm
, unsigned int, seconds
)
1216 return alarm_setitimer(seconds
);
1224 * The Alpha uses getxpid, getxuid, and getxgid instead. Maybe this
1225 * should be moved into arch/i386 instead?
1229 * sys_getpid - return the thread group id of the current process
1231 * Note, despite the name, this returns the tgid not the pid. The tgid and
1232 * the pid are identical unless CLONE_THREAD was specified on clone() in
1233 * which case the tgid is the same in all threads of the same group.
1235 * This is SMP safe as current->tgid does not change.
1237 SYSCALL_DEFINE0(getpid
)
1239 return task_tgid_vnr(current
);
1243 * Accessing ->real_parent is not SMP-safe, it could
1244 * change from under us. However, we can use a stale
1245 * value of ->real_parent under rcu_read_lock(), see
1246 * release_task()->call_rcu(delayed_put_task_struct).
1248 SYSCALL_DEFINE0(getppid
)
1253 pid
= task_tgid_vnr(current
->real_parent
);
1259 SYSCALL_DEFINE0(getuid
)
1261 /* Only we change this so SMP safe */
1262 return current_uid();
1265 SYSCALL_DEFINE0(geteuid
)
1267 /* Only we change this so SMP safe */
1268 return current_euid();
1271 SYSCALL_DEFINE0(getgid
)
1273 /* Only we change this so SMP safe */
1274 return current_gid();
1277 SYSCALL_DEFINE0(getegid
)
1279 /* Only we change this so SMP safe */
1280 return current_egid();
1285 static void process_timeout(unsigned long __data
)
1287 wake_up_process((struct task_struct
*)__data
);
1291 * schedule_timeout - sleep until timeout
1292 * @timeout: timeout value in jiffies
1294 * Make the current task sleep until @timeout jiffies have
1295 * elapsed. The routine will return immediately unless
1296 * the current task state has been set (see set_current_state()).
1298 * You can set the task state as follows -
1300 * %TASK_UNINTERRUPTIBLE - at least @timeout jiffies are guaranteed to
1301 * pass before the routine returns. The routine will return 0
1303 * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
1304 * delivered to the current task. In this case the remaining time
1305 * in jiffies will be returned, or 0 if the timer expired in time
1307 * The current task state is guaranteed to be TASK_RUNNING when this
1310 * Specifying a @timeout value of %MAX_SCHEDULE_TIMEOUT will schedule
1311 * the CPU away without a bound on the timeout. In this case the return
1312 * value will be %MAX_SCHEDULE_TIMEOUT.
1314 * In all cases the return value is guaranteed to be non-negative.
1316 signed long __sched
schedule_timeout(signed long timeout
)
1318 struct timer_list timer
;
1319 unsigned long expire
;
1323 case MAX_SCHEDULE_TIMEOUT
:
1325 * These two special cases are useful to be comfortable
1326 * in the caller. Nothing more. We could take
1327 * MAX_SCHEDULE_TIMEOUT from one of the negative value
1328 * but I' d like to return a valid offset (>=0) to allow
1329 * the caller to do everything it want with the retval.
1335 * Another bit of PARANOID. Note that the retval will be
1336 * 0 since no piece of kernel is supposed to do a check
1337 * for a negative retval of schedule_timeout() (since it
1338 * should never happens anyway). You just have the printk()
1339 * that will tell you if something is gone wrong and where.
1342 printk(KERN_ERR
"schedule_timeout: wrong timeout "
1343 "value %lx\n", timeout
);
1345 current
->state
= TASK_RUNNING
;
1350 expire
= timeout
+ jiffies
;
1352 setup_timer_on_stack(&timer
, process_timeout
, (unsigned long)current
);
1353 __mod_timer(&timer
, expire
, false);
1355 del_singleshot_timer_sync(&timer
);
1357 /* Remove the timer from the object tracker */
1358 destroy_timer_on_stack(&timer
);
1360 timeout
= expire
- jiffies
;
1363 return timeout
< 0 ? 0 : timeout
;
1365 EXPORT_SYMBOL(schedule_timeout
);
1368 * We can use __set_current_state() here because schedule_timeout() calls
1369 * schedule() unconditionally.
1371 signed long __sched
schedule_timeout_interruptible(signed long timeout
)
1373 __set_current_state(TASK_INTERRUPTIBLE
);
1374 return schedule_timeout(timeout
);
1376 EXPORT_SYMBOL(schedule_timeout_interruptible
);
1378 signed long __sched
schedule_timeout_killable(signed long timeout
)
1380 __set_current_state(TASK_KILLABLE
);
1381 return schedule_timeout(timeout
);
1383 EXPORT_SYMBOL(schedule_timeout_killable
);
1385 signed long __sched
schedule_timeout_uninterruptible(signed long timeout
)
1387 __set_current_state(TASK_UNINTERRUPTIBLE
);
1388 return schedule_timeout(timeout
);
1390 EXPORT_SYMBOL(schedule_timeout_uninterruptible
);
1392 /* Thread ID - the internal kernel "pid" */
1393 SYSCALL_DEFINE0(gettid
)
1395 return task_pid_vnr(current
);
1399 * do_sysinfo - fill in sysinfo struct
1400 * @info: pointer to buffer to fill
1402 int do_sysinfo(struct sysinfo
*info
)
1404 unsigned long mem_total
, sav_total
;
1405 unsigned int mem_unit
, bitcount
;
1408 memset(info
, 0, sizeof(struct sysinfo
));
1412 seq
= read_seqbegin(&xtime_lock
);
1415 * This is annoying. The below is the same thing
1416 * posix_get_clock_monotonic() does, but it wants to
1417 * take the lock which we want to cover the loads stuff
1421 getnstimeofday(&tp
);
1422 tp
.tv_sec
+= wall_to_monotonic
.tv_sec
;
1423 tp
.tv_nsec
+= wall_to_monotonic
.tv_nsec
;
1424 monotonic_to_bootbased(&tp
);
1425 if (tp
.tv_nsec
- NSEC_PER_SEC
>= 0) {
1426 tp
.tv_nsec
= tp
.tv_nsec
- NSEC_PER_SEC
;
1429 info
->uptime
= tp
.tv_sec
+ (tp
.tv_nsec
? 1 : 0);
1431 info
->loads
[0] = avenrun
[0] << (SI_LOAD_SHIFT
- FSHIFT
);
1432 info
->loads
[1] = avenrun
[1] << (SI_LOAD_SHIFT
- FSHIFT
);
1433 info
->loads
[2] = avenrun
[2] << (SI_LOAD_SHIFT
- FSHIFT
);
1435 info
->procs
= nr_threads
;
1436 } while (read_seqretry(&xtime_lock
, seq
));
1442 * If the sum of all the available memory (i.e. ram + swap)
1443 * is less than can be stored in a 32 bit unsigned long then
1444 * we can be binary compatible with 2.2.x kernels. If not,
1445 * well, in that case 2.2.x was broken anyways...
1447 * -Erik Andersen <andersee@debian.org>
1450 mem_total
= info
->totalram
+ info
->totalswap
;
1451 if (mem_total
< info
->totalram
|| mem_total
< info
->totalswap
)
1454 mem_unit
= info
->mem_unit
;
1455 while (mem_unit
> 1) {
1458 sav_total
= mem_total
;
1460 if (mem_total
< sav_total
)
1465 * If mem_total did not overflow, multiply all memory values by
1466 * info->mem_unit and set it to 1. This leaves things compatible
1467 * with 2.2.x, and also retains compatibility with earlier 2.4.x
1472 info
->totalram
<<= bitcount
;
1473 info
->freeram
<<= bitcount
;
1474 info
->sharedram
<<= bitcount
;
1475 info
->bufferram
<<= bitcount
;
1476 info
->totalswap
<<= bitcount
;
1477 info
->freeswap
<<= bitcount
;
1478 info
->totalhigh
<<= bitcount
;
1479 info
->freehigh
<<= bitcount
;
1485 SYSCALL_DEFINE1(sysinfo
, struct sysinfo __user
*, info
)
1491 if (copy_to_user(info
, &val
, sizeof(struct sysinfo
)))
1497 static int __cpuinit
init_timers_cpu(int cpu
)
1500 struct tvec_base
*base
;
1501 static char __cpuinitdata tvec_base_done
[NR_CPUS
];
1503 if (!tvec_base_done
[cpu
]) {
1504 static char boot_done
;
1508 * The APs use this path later in boot
1510 base
= kmalloc_node(sizeof(*base
),
1511 GFP_KERNEL
| __GFP_ZERO
,
1516 /* Make sure that tvec_base is 2 byte aligned */
1517 if (tbase_get_deferrable(base
)) {
1522 per_cpu(tvec_bases
, cpu
) = base
;
1525 * This is for the boot CPU - we use compile-time
1526 * static initialisation because per-cpu memory isn't
1527 * ready yet and because the memory allocators are not
1528 * initialised either.
1531 base
= &boot_tvec_bases
;
1533 tvec_base_done
[cpu
] = 1;
1535 base
= per_cpu(tvec_bases
, cpu
);
1538 spin_lock_init(&base
->lock
);
1540 for (j
= 0; j
< TVN_SIZE
; j
++) {
1541 INIT_LIST_HEAD(base
->tv5
.vec
+ j
);
1542 INIT_LIST_HEAD(base
->tv4
.vec
+ j
);
1543 INIT_LIST_HEAD(base
->tv3
.vec
+ j
);
1544 INIT_LIST_HEAD(base
->tv2
.vec
+ j
);
1546 for (j
= 0; j
< TVR_SIZE
; j
++)
1547 INIT_LIST_HEAD(base
->tv1
.vec
+ j
);
1549 base
->timer_jiffies
= jiffies
;
1553 #ifdef CONFIG_HOTPLUG_CPU
1554 static void migrate_timer_list(struct tvec_base
*new_base
, struct list_head
*head
)
1556 struct timer_list
*timer
;
1558 while (!list_empty(head
)) {
1559 timer
= list_first_entry(head
, struct timer_list
, entry
);
1560 detach_timer(timer
, 0);
1561 timer_set_base(timer
, new_base
);
1562 internal_add_timer(new_base
, timer
);
1566 static void __cpuinit
migrate_timers(int cpu
)
1568 struct tvec_base
*old_base
;
1569 struct tvec_base
*new_base
;
1572 BUG_ON(cpu_online(cpu
));
1573 old_base
= per_cpu(tvec_bases
, cpu
);
1574 new_base
= get_cpu_var(tvec_bases
);
1576 * The caller is globally serialized and nobody else
1577 * takes two locks at once, deadlock is not possible.
1579 spin_lock_irq(&new_base
->lock
);
1580 spin_lock_nested(&old_base
->lock
, SINGLE_DEPTH_NESTING
);
1582 BUG_ON(old_base
->running_timer
);
1584 for (i
= 0; i
< TVR_SIZE
; i
++)
1585 migrate_timer_list(new_base
, old_base
->tv1
.vec
+ i
);
1586 for (i
= 0; i
< TVN_SIZE
; i
++) {
1587 migrate_timer_list(new_base
, old_base
->tv2
.vec
+ i
);
1588 migrate_timer_list(new_base
, old_base
->tv3
.vec
+ i
);
1589 migrate_timer_list(new_base
, old_base
->tv4
.vec
+ i
);
1590 migrate_timer_list(new_base
, old_base
->tv5
.vec
+ i
);
1593 spin_unlock(&old_base
->lock
);
1594 spin_unlock_irq(&new_base
->lock
);
1595 put_cpu_var(tvec_bases
);
1597 #endif /* CONFIG_HOTPLUG_CPU */
1599 static int __cpuinit
timer_cpu_notify(struct notifier_block
*self
,
1600 unsigned long action
, void *hcpu
)
1602 long cpu
= (long)hcpu
;
1604 case CPU_UP_PREPARE
:
1605 case CPU_UP_PREPARE_FROZEN
:
1606 if (init_timers_cpu(cpu
) < 0)
1609 #ifdef CONFIG_HOTPLUG_CPU
1611 case CPU_DEAD_FROZEN
:
1612 migrate_timers(cpu
);
1621 static struct notifier_block __cpuinitdata timers_nb
= {
1622 .notifier_call
= timer_cpu_notify
,
1626 void __init
init_timers(void)
1628 int err
= timer_cpu_notify(&timers_nb
, (unsigned long)CPU_UP_PREPARE
,
1629 (void *)(long)smp_processor_id());
1633 BUG_ON(err
== NOTIFY_BAD
);
1634 register_cpu_notifier(&timers_nb
);
1635 open_softirq(TIMER_SOFTIRQ
, run_timer_softirq
);
1639 * msleep - sleep safely even with waitqueue interruptions
1640 * @msecs: Time in milliseconds to sleep for
1642 void msleep(unsigned int msecs
)
1644 unsigned long timeout
= msecs_to_jiffies(msecs
) + 1;
1647 timeout
= schedule_timeout_uninterruptible(timeout
);
1650 EXPORT_SYMBOL(msleep
);
1653 * msleep_interruptible - sleep waiting for signals
1654 * @msecs: Time in milliseconds to sleep for
1656 unsigned long msleep_interruptible(unsigned int msecs
)
1658 unsigned long timeout
= msecs_to_jiffies(msecs
) + 1;
1660 while (timeout
&& !signal_pending(current
))
1661 timeout
= schedule_timeout_interruptible(timeout
);
1662 return jiffies_to_msecs(timeout
);
1665 EXPORT_SYMBOL(msleep_interruptible
);