2 * Implement CPU time clocks for the POSIX clock interface.
5 #include <linux/sched.h>
6 #include <linux/posix-timers.h>
7 #include <linux/errno.h>
8 #include <linux/math64.h>
9 #include <asm/uaccess.h>
10 #include <linux/kernel_stat.h>
11 #include <trace/events/timer.h>
12 #include <linux/random.h>
13 #include <linux/tick.h>
14 #include <linux/workqueue.h>
17 * Called after updating RLIMIT_CPU to run cpu timer and update
18 * tsk->signal->cputime_expires expiration cache if necessary. Needs
19 * siglock protection since other code may update expiration cache as
22 void update_rlimit_cpu(struct task_struct
*task
, unsigned long rlim_new
)
24 cputime_t cputime
= secs_to_cputime(rlim_new
);
26 spin_lock_irq(&task
->sighand
->siglock
);
27 set_process_cpu_timer(task
, CPUCLOCK_PROF
, &cputime
, NULL
);
28 spin_unlock_irq(&task
->sighand
->siglock
);
31 static int check_clock(const clockid_t which_clock
)
34 struct task_struct
*p
;
35 const pid_t pid
= CPUCLOCK_PID(which_clock
);
37 if (CPUCLOCK_WHICH(which_clock
) >= CPUCLOCK_MAX
)
44 p
= find_task_by_vpid(pid
);
45 if (!p
|| !(CPUCLOCK_PERTHREAD(which_clock
) ?
46 same_thread_group(p
, current
) : has_group_leader_pid(p
))) {
54 static inline unsigned long long
55 timespec_to_sample(const clockid_t which_clock
, const struct timespec
*tp
)
57 unsigned long long ret
;
59 ret
= 0; /* high half always zero when .cpu used */
60 if (CPUCLOCK_WHICH(which_clock
) == CPUCLOCK_SCHED
) {
61 ret
= (unsigned long long)tp
->tv_sec
* NSEC_PER_SEC
+ tp
->tv_nsec
;
63 ret
= cputime_to_expires(timespec_to_cputime(tp
));
68 static void sample_to_timespec(const clockid_t which_clock
,
69 unsigned long long expires
,
72 if (CPUCLOCK_WHICH(which_clock
) == CPUCLOCK_SCHED
)
73 *tp
= ns_to_timespec(expires
);
75 cputime_to_timespec((__force cputime_t
)expires
, tp
);
79 * Update expiry time from increment, and increase overrun count,
80 * given the current clock sample.
82 static void bump_cpu_timer(struct k_itimer
*timer
,
83 unsigned long long now
)
86 unsigned long long delta
, incr
;
88 if (timer
->it
.cpu
.incr
== 0)
91 if (now
< timer
->it
.cpu
.expires
)
94 incr
= timer
->it
.cpu
.incr
;
95 delta
= now
+ incr
- timer
->it
.cpu
.expires
;
97 /* Don't use (incr*2 < delta), incr*2 might overflow. */
98 for (i
= 0; incr
< delta
- incr
; i
++)
101 for (; i
>= 0; incr
>>= 1, i
--) {
105 timer
->it
.cpu
.expires
+= incr
;
106 timer
->it_overrun
+= 1 << i
;
112 * task_cputime_zero - Check a task_cputime struct for all zero fields.
114 * @cputime: The struct to compare.
116 * Checks @cputime to see if all fields are zero. Returns true if all fields
117 * are zero, false if any field is nonzero.
119 static inline int task_cputime_zero(const struct task_cputime
*cputime
)
121 if (!cputime
->utime
&& !cputime
->stime
&& !cputime
->sum_exec_runtime
)
126 static inline unsigned long long prof_ticks(struct task_struct
*p
)
128 cputime_t utime
, stime
;
130 task_cputime(p
, &utime
, &stime
);
132 return cputime_to_expires(utime
+ stime
);
134 static inline unsigned long long virt_ticks(struct task_struct
*p
)
138 task_cputime(p
, &utime
, NULL
);
140 return cputime_to_expires(utime
);
144 posix_cpu_clock_getres(const clockid_t which_clock
, struct timespec
*tp
)
146 int error
= check_clock(which_clock
);
149 tp
->tv_nsec
= ((NSEC_PER_SEC
+ HZ
- 1) / HZ
);
150 if (CPUCLOCK_WHICH(which_clock
) == CPUCLOCK_SCHED
) {
152 * If sched_clock is using a cycle counter, we
153 * don't have any idea of its true resolution
154 * exported, but it is much more than 1s/HZ.
163 posix_cpu_clock_set(const clockid_t which_clock
, const struct timespec
*tp
)
166 * You can never reset a CPU clock, but we check for other errors
167 * in the call before failing with EPERM.
169 int error
= check_clock(which_clock
);
178 * Sample a per-thread clock for the given task.
180 static int cpu_clock_sample(const clockid_t which_clock
, struct task_struct
*p
,
181 unsigned long long *sample
)
183 switch (CPUCLOCK_WHICH(which_clock
)) {
187 *sample
= prof_ticks(p
);
190 *sample
= virt_ticks(p
);
193 *sample
= task_sched_runtime(p
);
199 static void update_gt_cputime(struct task_cputime
*a
, struct task_cputime
*b
)
201 if (b
->utime
> a
->utime
)
204 if (b
->stime
> a
->stime
)
207 if (b
->sum_exec_runtime
> a
->sum_exec_runtime
)
208 a
->sum_exec_runtime
= b
->sum_exec_runtime
;
211 void thread_group_cputimer(struct task_struct
*tsk
, struct task_cputime
*times
)
213 struct thread_group_cputimer
*cputimer
= &tsk
->signal
->cputimer
;
214 struct task_cputime sum
;
217 if (!cputimer
->running
) {
219 * The POSIX timer interface allows for absolute time expiry
220 * values through the TIMER_ABSTIME flag, therefore we have
221 * to synchronize the timer to the clock every time we start
224 thread_group_cputime(tsk
, &sum
);
225 raw_spin_lock_irqsave(&cputimer
->lock
, flags
);
226 cputimer
->running
= 1;
227 update_gt_cputime(&cputimer
->cputime
, &sum
);
229 raw_spin_lock_irqsave(&cputimer
->lock
, flags
);
230 *times
= cputimer
->cputime
;
231 raw_spin_unlock_irqrestore(&cputimer
->lock
, flags
);
235 * Sample a process (thread group) clock for the given group_leader task.
236 * Must be called with tasklist_lock held for reading.
238 static int cpu_clock_sample_group(const clockid_t which_clock
,
239 struct task_struct
*p
,
240 unsigned long long *sample
)
242 struct task_cputime cputime
;
244 switch (CPUCLOCK_WHICH(which_clock
)) {
248 thread_group_cputime(p
, &cputime
);
249 *sample
= cputime_to_expires(cputime
.utime
+ cputime
.stime
);
252 thread_group_cputime(p
, &cputime
);
253 *sample
= cputime_to_expires(cputime
.utime
);
256 thread_group_cputime(p
, &cputime
);
257 *sample
= cputime
.sum_exec_runtime
;
263 static int posix_cpu_clock_get_task(struct task_struct
*tsk
,
264 const clockid_t which_clock
,
268 unsigned long long rtn
;
270 if (CPUCLOCK_PERTHREAD(which_clock
)) {
271 if (same_thread_group(tsk
, current
))
272 err
= cpu_clock_sample(which_clock
, tsk
, &rtn
);
275 struct sighand_struct
*sighand
;
278 * while_each_thread() is not yet entirely RCU safe,
279 * keep locking the group while sampling process
282 sighand
= lock_task_sighand(tsk
, &flags
);
286 if (tsk
== current
|| thread_group_leader(tsk
))
287 err
= cpu_clock_sample_group(which_clock
, tsk
, &rtn
);
289 unlock_task_sighand(tsk
, &flags
);
293 sample_to_timespec(which_clock
, rtn
, tp
);
299 static int posix_cpu_clock_get(const clockid_t which_clock
, struct timespec
*tp
)
301 const pid_t pid
= CPUCLOCK_PID(which_clock
);
306 * Special case constant value for our own clocks.
307 * We don't have to do any lookup to find ourselves.
309 err
= posix_cpu_clock_get_task(current
, which_clock
, tp
);
312 * Find the given PID, and validate that the caller
313 * should be able to see it.
315 struct task_struct
*p
;
317 p
= find_task_by_vpid(pid
);
319 err
= posix_cpu_clock_get_task(p
, which_clock
, tp
);
328 * Validate the clockid_t for a new CPU-clock timer, and initialize the timer.
329 * This is called from sys_timer_create() and do_cpu_nanosleep() with the
330 * new timer already all-zeros initialized.
332 static int posix_cpu_timer_create(struct k_itimer
*new_timer
)
335 const pid_t pid
= CPUCLOCK_PID(new_timer
->it_clock
);
336 struct task_struct
*p
;
338 if (CPUCLOCK_WHICH(new_timer
->it_clock
) >= CPUCLOCK_MAX
)
341 INIT_LIST_HEAD(&new_timer
->it
.cpu
.entry
);
344 if (CPUCLOCK_PERTHREAD(new_timer
->it_clock
)) {
348 p
= find_task_by_vpid(pid
);
349 if (p
&& !same_thread_group(p
, current
))
354 p
= current
->group_leader
;
356 p
= find_task_by_vpid(pid
);
357 if (p
&& !has_group_leader_pid(p
))
361 new_timer
->it
.cpu
.task
= p
;
373 * Clean up a CPU-clock timer that is about to be destroyed.
374 * This is called from timer deletion with the timer already locked.
375 * If we return TIMER_RETRY, it's necessary to release the timer's lock
376 * and try again. (This happens when the timer is in the middle of firing.)
378 static int posix_cpu_timer_del(struct k_itimer
*timer
)
382 struct sighand_struct
*sighand
;
383 struct task_struct
*p
= timer
->it
.cpu
.task
;
385 WARN_ON_ONCE(p
== NULL
);
388 * Protect against sighand release/switch in exit/exec and process/
389 * thread timer list entry concurrent read/writes.
391 sighand
= lock_task_sighand(p
, &flags
);
392 if (unlikely(sighand
== NULL
)) {
394 * We raced with the reaping of the task.
395 * The deletion should have cleared us off the list.
397 BUG_ON(!list_empty(&timer
->it
.cpu
.entry
));
399 if (timer
->it
.cpu
.firing
)
402 list_del(&timer
->it
.cpu
.entry
);
404 unlock_task_sighand(p
, &flags
);
413 static void cleanup_timers_list(struct list_head
*head
)
415 struct cpu_timer_list
*timer
, *next
;
417 list_for_each_entry_safe(timer
, next
, head
, entry
)
418 list_del_init(&timer
->entry
);
422 * Clean out CPU timers still ticking when a thread exited. The task
423 * pointer is cleared, and the expiry time is replaced with the residual
424 * time for later timer_gettime calls to return.
425 * This must be called with the siglock held.
427 static void cleanup_timers(struct list_head
*head
)
429 cleanup_timers_list(head
);
430 cleanup_timers_list(++head
);
431 cleanup_timers_list(++head
);
435 * These are both called with the siglock held, when the current thread
436 * is being reaped. When the final (leader) thread in the group is reaped,
437 * posix_cpu_timers_exit_group will be called after posix_cpu_timers_exit.
439 void posix_cpu_timers_exit(struct task_struct
*tsk
)
441 add_device_randomness((const void*) &tsk
->se
.sum_exec_runtime
,
442 sizeof(unsigned long long));
443 cleanup_timers(tsk
->cpu_timers
);
446 void posix_cpu_timers_exit_group(struct task_struct
*tsk
)
448 cleanup_timers(tsk
->signal
->cpu_timers
);
451 static inline int expires_gt(cputime_t expires
, cputime_t new_exp
)
453 return expires
== 0 || expires
> new_exp
;
457 * Insert the timer on the appropriate list before any timers that
458 * expire later. This must be called with the tasklist_lock held
459 * for reading, interrupts disabled and p->sighand->siglock taken.
461 static void arm_timer(struct k_itimer
*timer
)
463 struct task_struct
*p
= timer
->it
.cpu
.task
;
464 struct list_head
*head
, *listpos
;
465 struct task_cputime
*cputime_expires
;
466 struct cpu_timer_list
*const nt
= &timer
->it
.cpu
;
467 struct cpu_timer_list
*next
;
469 if (CPUCLOCK_PERTHREAD(timer
->it_clock
)) {
470 head
= p
->cpu_timers
;
471 cputime_expires
= &p
->cputime_expires
;
473 head
= p
->signal
->cpu_timers
;
474 cputime_expires
= &p
->signal
->cputime_expires
;
476 head
+= CPUCLOCK_WHICH(timer
->it_clock
);
479 list_for_each_entry(next
, head
, entry
) {
480 if (nt
->expires
< next
->expires
)
482 listpos
= &next
->entry
;
484 list_add(&nt
->entry
, listpos
);
486 if (listpos
== head
) {
487 unsigned long long exp
= nt
->expires
;
490 * We are the new earliest-expiring POSIX 1.b timer, hence
491 * need to update expiration cache. Take into account that
492 * for process timers we share expiration cache with itimers
493 * and RLIMIT_CPU and for thread timers with RLIMIT_RTTIME.
496 switch (CPUCLOCK_WHICH(timer
->it_clock
)) {
498 if (expires_gt(cputime_expires
->prof_exp
, expires_to_cputime(exp
)))
499 cputime_expires
->prof_exp
= expires_to_cputime(exp
);
502 if (expires_gt(cputime_expires
->virt_exp
, expires_to_cputime(exp
)))
503 cputime_expires
->virt_exp
= expires_to_cputime(exp
);
506 if (cputime_expires
->sched_exp
== 0 ||
507 cputime_expires
->sched_exp
> exp
)
508 cputime_expires
->sched_exp
= exp
;
515 * The timer is locked, fire it and arrange for its reload.
517 static void cpu_timer_fire(struct k_itimer
*timer
)
519 if ((timer
->it_sigev_notify
& ~SIGEV_THREAD_ID
) == SIGEV_NONE
) {
521 * User don't want any signal.
523 timer
->it
.cpu
.expires
= 0;
524 } else if (unlikely(timer
->sigq
== NULL
)) {
526 * This a special case for clock_nanosleep,
527 * not a normal timer from sys_timer_create.
529 wake_up_process(timer
->it_process
);
530 timer
->it
.cpu
.expires
= 0;
531 } else if (timer
->it
.cpu
.incr
== 0) {
533 * One-shot timer. Clear it as soon as it's fired.
535 posix_timer_event(timer
, 0);
536 timer
->it
.cpu
.expires
= 0;
537 } else if (posix_timer_event(timer
, ++timer
->it_requeue_pending
)) {
539 * The signal did not get queued because the signal
540 * was ignored, so we won't get any callback to
541 * reload the timer. But we need to keep it
542 * ticking in case the signal is deliverable next time.
544 posix_cpu_timer_schedule(timer
);
549 * Sample a process (thread group) timer for the given group_leader task.
550 * Must be called with tasklist_lock held for reading.
552 static int cpu_timer_sample_group(const clockid_t which_clock
,
553 struct task_struct
*p
,
554 unsigned long long *sample
)
556 struct task_cputime cputime
;
558 thread_group_cputimer(p
, &cputime
);
559 switch (CPUCLOCK_WHICH(which_clock
)) {
563 *sample
= cputime_to_expires(cputime
.utime
+ cputime
.stime
);
566 *sample
= cputime_to_expires(cputime
.utime
);
569 *sample
= cputime
.sum_exec_runtime
+ task_delta_exec(p
);
575 #ifdef CONFIG_NO_HZ_FULL
576 static void nohz_kick_work_fn(struct work_struct
*work
)
578 tick_nohz_full_kick_all();
581 static DECLARE_WORK(nohz_kick_work
, nohz_kick_work_fn
);
584 * We need the IPIs to be sent from sane process context.
585 * The posix cpu timers are always set with irqs disabled.
587 static void posix_cpu_timer_kick_nohz(void)
589 if (context_tracking_is_enabled())
590 schedule_work(&nohz_kick_work
);
593 bool posix_cpu_timers_can_stop_tick(struct task_struct
*tsk
)
595 if (!task_cputime_zero(&tsk
->cputime_expires
))
598 if (tsk
->signal
->cputimer
.running
)
604 static inline void posix_cpu_timer_kick_nohz(void) { }
608 * Guts of sys_timer_settime for CPU timers.
609 * This is called with the timer locked and interrupts disabled.
610 * If we return TIMER_RETRY, it's necessary to release the timer's lock
611 * and try again. (This happens when the timer is in the middle of firing.)
613 static int posix_cpu_timer_set(struct k_itimer
*timer
, int flags
,
614 struct itimerspec
*new, struct itimerspec
*old
)
616 struct task_struct
*p
= timer
->it
.cpu
.task
;
617 unsigned long long old_expires
, new_expires
, old_incr
, val
;
620 WARN_ON_ONCE(p
== NULL
);
622 new_expires
= timespec_to_sample(timer
->it_clock
, &new->it_value
);
624 read_lock(&tasklist_lock
);
626 * We need the tasklist_lock to protect against reaping that
627 * clears p->sighand. If p has just been reaped, we can no
628 * longer get any information about it at all.
630 if (unlikely(p
->sighand
== NULL
)) {
631 read_unlock(&tasklist_lock
);
636 * Disarm any old timer after extracting its expiry time.
638 BUG_ON(!irqs_disabled());
641 old_incr
= timer
->it
.cpu
.incr
;
642 spin_lock(&p
->sighand
->siglock
);
643 old_expires
= timer
->it
.cpu
.expires
;
644 if (unlikely(timer
->it
.cpu
.firing
)) {
645 timer
->it
.cpu
.firing
= -1;
648 list_del_init(&timer
->it
.cpu
.entry
);
651 * We need to sample the current value to convert the new
652 * value from to relative and absolute, and to convert the
653 * old value from absolute to relative. To set a process
654 * timer, we need a sample to balance the thread expiry
655 * times (in arm_timer). With an absolute time, we must
656 * check if it's already passed. In short, we need a sample.
658 if (CPUCLOCK_PERTHREAD(timer
->it_clock
)) {
659 cpu_clock_sample(timer
->it_clock
, p
, &val
);
661 cpu_timer_sample_group(timer
->it_clock
, p
, &val
);
665 if (old_expires
== 0) {
666 old
->it_value
.tv_sec
= 0;
667 old
->it_value
.tv_nsec
= 0;
670 * Update the timer in case it has
671 * overrun already. If it has,
672 * we'll report it as having overrun
673 * and with the next reloaded timer
674 * already ticking, though we are
675 * swallowing that pending
676 * notification here to install the
679 bump_cpu_timer(timer
, val
);
680 if (val
< timer
->it
.cpu
.expires
) {
681 old_expires
= timer
->it
.cpu
.expires
- val
;
682 sample_to_timespec(timer
->it_clock
,
686 old
->it_value
.tv_nsec
= 1;
687 old
->it_value
.tv_sec
= 0;
694 * We are colliding with the timer actually firing.
695 * Punt after filling in the timer's old value, and
696 * disable this firing since we are already reporting
697 * it as an overrun (thanks to bump_cpu_timer above).
699 spin_unlock(&p
->sighand
->siglock
);
700 read_unlock(&tasklist_lock
);
704 if (new_expires
!= 0 && !(flags
& TIMER_ABSTIME
)) {
709 * Install the new expiry time (or zero).
710 * For a timer with no notification action, we don't actually
711 * arm the timer (we'll just fake it for timer_gettime).
713 timer
->it
.cpu
.expires
= new_expires
;
714 if (new_expires
!= 0 && val
< new_expires
) {
718 spin_unlock(&p
->sighand
->siglock
);
719 read_unlock(&tasklist_lock
);
722 * Install the new reload setting, and
723 * set up the signal and overrun bookkeeping.
725 timer
->it
.cpu
.incr
= timespec_to_sample(timer
->it_clock
,
729 * This acts as a modification timestamp for the timer,
730 * so any automatic reload attempt will punt on seeing
731 * that we have reset the timer manually.
733 timer
->it_requeue_pending
= (timer
->it_requeue_pending
+ 2) &
735 timer
->it_overrun_last
= 0;
736 timer
->it_overrun
= -1;
738 if (new_expires
!= 0 && !(val
< new_expires
)) {
740 * The designated time already passed, so we notify
741 * immediately, even if the thread never runs to
742 * accumulate more time on this clock.
744 cpu_timer_fire(timer
);
750 sample_to_timespec(timer
->it_clock
,
751 old_incr
, &old
->it_interval
);
754 posix_cpu_timer_kick_nohz();
758 static void posix_cpu_timer_get(struct k_itimer
*timer
, struct itimerspec
*itp
)
760 unsigned long long now
;
761 struct task_struct
*p
= timer
->it
.cpu
.task
;
763 WARN_ON_ONCE(p
== NULL
);
766 * Easy part: convert the reload time.
768 sample_to_timespec(timer
->it_clock
,
769 timer
->it
.cpu
.incr
, &itp
->it_interval
);
771 if (timer
->it
.cpu
.expires
== 0) { /* Timer not armed at all. */
772 itp
->it_value
.tv_sec
= itp
->it_value
.tv_nsec
= 0;
777 * Sample the clock to take the difference with the expiry time.
779 if (CPUCLOCK_PERTHREAD(timer
->it_clock
)) {
780 cpu_clock_sample(timer
->it_clock
, p
, &now
);
782 read_lock(&tasklist_lock
);
783 if (unlikely(p
->sighand
== NULL
)) {
785 * The process has been reaped.
786 * We can't even collect a sample any more.
787 * Call the timer disarmed, nothing else to do.
789 timer
->it
.cpu
.expires
= 0;
790 sample_to_timespec(timer
->it_clock
, timer
->it
.cpu
.expires
,
792 read_unlock(&tasklist_lock
);
794 cpu_timer_sample_group(timer
->it_clock
, p
, &now
);
796 read_unlock(&tasklist_lock
);
799 if (now
< timer
->it
.cpu
.expires
) {
800 sample_to_timespec(timer
->it_clock
,
801 timer
->it
.cpu
.expires
- now
,
805 * The timer should have expired already, but the firing
806 * hasn't taken place yet. Say it's just about to expire.
808 itp
->it_value
.tv_nsec
= 1;
809 itp
->it_value
.tv_sec
= 0;
813 static unsigned long long
814 check_timers_list(struct list_head
*timers
,
815 struct list_head
*firing
,
816 unsigned long long curr
)
820 while (!list_empty(timers
)) {
821 struct cpu_timer_list
*t
;
823 t
= list_first_entry(timers
, struct cpu_timer_list
, entry
);
825 if (!--maxfire
|| curr
< t
->expires
)
829 list_move_tail(&t
->entry
, firing
);
836 * Check for any per-thread CPU timers that have fired and move them off
837 * the tsk->cpu_timers[N] list onto the firing list. Here we update the
838 * tsk->it_*_expires values to reflect the remaining thread CPU timers.
840 static void check_thread_timers(struct task_struct
*tsk
,
841 struct list_head
*firing
)
843 struct list_head
*timers
= tsk
->cpu_timers
;
844 struct signal_struct
*const sig
= tsk
->signal
;
845 struct task_cputime
*tsk_expires
= &tsk
->cputime_expires
;
846 unsigned long long expires
;
849 expires
= check_timers_list(timers
, firing
, prof_ticks(tsk
));
850 tsk_expires
->prof_exp
= expires_to_cputime(expires
);
852 expires
= check_timers_list(++timers
, firing
, virt_ticks(tsk
));
853 tsk_expires
->virt_exp
= expires_to_cputime(expires
);
855 tsk_expires
->sched_exp
= check_timers_list(++timers
, firing
,
856 tsk
->se
.sum_exec_runtime
);
859 * Check for the special case thread timers.
861 soft
= ACCESS_ONCE(sig
->rlim
[RLIMIT_RTTIME
].rlim_cur
);
862 if (soft
!= RLIM_INFINITY
) {
864 ACCESS_ONCE(sig
->rlim
[RLIMIT_RTTIME
].rlim_max
);
866 if (hard
!= RLIM_INFINITY
&&
867 tsk
->rt
.timeout
> DIV_ROUND_UP(hard
, USEC_PER_SEC
/HZ
)) {
869 * At the hard limit, we just die.
870 * No need to calculate anything else now.
872 __group_send_sig_info(SIGKILL
, SEND_SIG_PRIV
, tsk
);
875 if (tsk
->rt
.timeout
> DIV_ROUND_UP(soft
, USEC_PER_SEC
/HZ
)) {
877 * At the soft limit, send a SIGXCPU every second.
880 soft
+= USEC_PER_SEC
;
881 sig
->rlim
[RLIMIT_RTTIME
].rlim_cur
= soft
;
884 "RT Watchdog Timeout: %s[%d]\n",
885 tsk
->comm
, task_pid_nr(tsk
));
886 __group_send_sig_info(SIGXCPU
, SEND_SIG_PRIV
, tsk
);
891 static void stop_process_timers(struct signal_struct
*sig
)
893 struct thread_group_cputimer
*cputimer
= &sig
->cputimer
;
896 raw_spin_lock_irqsave(&cputimer
->lock
, flags
);
897 cputimer
->running
= 0;
898 raw_spin_unlock_irqrestore(&cputimer
->lock
, flags
);
901 static u32 onecputick
;
903 static void check_cpu_itimer(struct task_struct
*tsk
, struct cpu_itimer
*it
,
904 unsigned long long *expires
,
905 unsigned long long cur_time
, int signo
)
910 if (cur_time
>= it
->expires
) {
912 it
->expires
+= it
->incr
;
913 it
->error
+= it
->incr_error
;
914 if (it
->error
>= onecputick
) {
915 it
->expires
-= cputime_one_jiffy
;
916 it
->error
-= onecputick
;
922 trace_itimer_expire(signo
== SIGPROF
?
923 ITIMER_PROF
: ITIMER_VIRTUAL
,
924 tsk
->signal
->leader_pid
, cur_time
);
925 __group_send_sig_info(signo
, SEND_SIG_PRIV
, tsk
);
928 if (it
->expires
&& (!*expires
|| it
->expires
< *expires
)) {
929 *expires
= it
->expires
;
934 * Check for any per-thread CPU timers that have fired and move them
935 * off the tsk->*_timers list onto the firing list. Per-thread timers
936 * have already been taken off.
938 static void check_process_timers(struct task_struct
*tsk
,
939 struct list_head
*firing
)
941 struct signal_struct
*const sig
= tsk
->signal
;
942 unsigned long long utime
, ptime
, virt_expires
, prof_expires
;
943 unsigned long long sum_sched_runtime
, sched_expires
;
944 struct list_head
*timers
= sig
->cpu_timers
;
945 struct task_cputime cputime
;
949 * Collect the current process totals.
951 thread_group_cputimer(tsk
, &cputime
);
952 utime
= cputime_to_expires(cputime
.utime
);
953 ptime
= utime
+ cputime_to_expires(cputime
.stime
);
954 sum_sched_runtime
= cputime
.sum_exec_runtime
;
956 prof_expires
= check_timers_list(timers
, firing
, ptime
);
957 virt_expires
= check_timers_list(++timers
, firing
, utime
);
958 sched_expires
= check_timers_list(++timers
, firing
, sum_sched_runtime
);
961 * Check for the special case process timers.
963 check_cpu_itimer(tsk
, &sig
->it
[CPUCLOCK_PROF
], &prof_expires
, ptime
,
965 check_cpu_itimer(tsk
, &sig
->it
[CPUCLOCK_VIRT
], &virt_expires
, utime
,
967 soft
= ACCESS_ONCE(sig
->rlim
[RLIMIT_CPU
].rlim_cur
);
968 if (soft
!= RLIM_INFINITY
) {
969 unsigned long psecs
= cputime_to_secs(ptime
);
971 ACCESS_ONCE(sig
->rlim
[RLIMIT_CPU
].rlim_max
);
975 * At the hard limit, we just die.
976 * No need to calculate anything else now.
978 __group_send_sig_info(SIGKILL
, SEND_SIG_PRIV
, tsk
);
983 * At the soft limit, send a SIGXCPU every second.
985 __group_send_sig_info(SIGXCPU
, SEND_SIG_PRIV
, tsk
);
988 sig
->rlim
[RLIMIT_CPU
].rlim_cur
= soft
;
991 x
= secs_to_cputime(soft
);
992 if (!prof_expires
|| x
< prof_expires
) {
997 sig
->cputime_expires
.prof_exp
= expires_to_cputime(prof_expires
);
998 sig
->cputime_expires
.virt_exp
= expires_to_cputime(virt_expires
);
999 sig
->cputime_expires
.sched_exp
= sched_expires
;
1000 if (task_cputime_zero(&sig
->cputime_expires
))
1001 stop_process_timers(sig
);
1005 * This is called from the signal code (via do_schedule_next_timer)
1006 * when the last timer signal was delivered and we have to reload the timer.
1008 void posix_cpu_timer_schedule(struct k_itimer
*timer
)
1010 struct task_struct
*p
= timer
->it
.cpu
.task
;
1011 unsigned long long now
;
1013 WARN_ON_ONCE(p
== NULL
);
1016 * Fetch the current sample and update the timer's expiry time.
1018 if (CPUCLOCK_PERTHREAD(timer
->it_clock
)) {
1019 cpu_clock_sample(timer
->it_clock
, p
, &now
);
1020 bump_cpu_timer(timer
, now
);
1021 if (unlikely(p
->exit_state
))
1024 read_lock(&tasklist_lock
); /* arm_timer needs it. */
1025 spin_lock(&p
->sighand
->siglock
);
1027 read_lock(&tasklist_lock
);
1028 if (unlikely(p
->sighand
== NULL
)) {
1030 * The process has been reaped.
1031 * We can't even collect a sample any more.
1033 timer
->it
.cpu
.expires
= 0;
1034 read_unlock(&tasklist_lock
);
1036 } else if (unlikely(p
->exit_state
) && thread_group_empty(p
)) {
1037 read_unlock(&tasklist_lock
);
1038 /* Optimizations: if the process is dying, no need to rearm */
1041 spin_lock(&p
->sighand
->siglock
);
1042 cpu_timer_sample_group(timer
->it_clock
, p
, &now
);
1043 bump_cpu_timer(timer
, now
);
1044 /* Leave the tasklist_lock locked for the call below. */
1048 * Now re-arm for the new expiry time.
1050 BUG_ON(!irqs_disabled());
1052 spin_unlock(&p
->sighand
->siglock
);
1053 read_unlock(&tasklist_lock
);
1055 /* Kick full dynticks CPUs in case they need to tick on the new timer */
1056 posix_cpu_timer_kick_nohz();
1059 timer
->it_overrun_last
= timer
->it_overrun
;
1060 timer
->it_overrun
= -1;
1061 ++timer
->it_requeue_pending
;
1065 * task_cputime_expired - Compare two task_cputime entities.
1067 * @sample: The task_cputime structure to be checked for expiration.
1068 * @expires: Expiration times, against which @sample will be checked.
1070 * Checks @sample against @expires to see if any field of @sample has expired.
1071 * Returns true if any field of the former is greater than the corresponding
1072 * field of the latter if the latter field is set. Otherwise returns false.
1074 static inline int task_cputime_expired(const struct task_cputime
*sample
,
1075 const struct task_cputime
*expires
)
1077 if (expires
->utime
&& sample
->utime
>= expires
->utime
)
1079 if (expires
->stime
&& sample
->utime
+ sample
->stime
>= expires
->stime
)
1081 if (expires
->sum_exec_runtime
!= 0 &&
1082 sample
->sum_exec_runtime
>= expires
->sum_exec_runtime
)
1088 * fastpath_timer_check - POSIX CPU timers fast path.
1090 * @tsk: The task (thread) being checked.
1092 * Check the task and thread group timers. If both are zero (there are no
1093 * timers set) return false. Otherwise snapshot the task and thread group
1094 * timers and compare them with the corresponding expiration times. Return
1095 * true if a timer has expired, else return false.
1097 static inline int fastpath_timer_check(struct task_struct
*tsk
)
1099 struct signal_struct
*sig
;
1100 cputime_t utime
, stime
;
1102 task_cputime(tsk
, &utime
, &stime
);
1104 if (!task_cputime_zero(&tsk
->cputime_expires
)) {
1105 struct task_cputime task_sample
= {
1108 .sum_exec_runtime
= tsk
->se
.sum_exec_runtime
1111 if (task_cputime_expired(&task_sample
, &tsk
->cputime_expires
))
1116 if (sig
->cputimer
.running
) {
1117 struct task_cputime group_sample
;
1119 raw_spin_lock(&sig
->cputimer
.lock
);
1120 group_sample
= sig
->cputimer
.cputime
;
1121 raw_spin_unlock(&sig
->cputimer
.lock
);
1123 if (task_cputime_expired(&group_sample
, &sig
->cputime_expires
))
1131 * This is called from the timer interrupt handler. The irq handler has
1132 * already updated our counts. We need to check if any timers fire now.
1133 * Interrupts are disabled.
1135 void run_posix_cpu_timers(struct task_struct
*tsk
)
1138 struct k_itimer
*timer
, *next
;
1139 unsigned long flags
;
1141 BUG_ON(!irqs_disabled());
1144 * The fast path checks that there are no expired thread or thread
1145 * group timers. If that's so, just return.
1147 if (!fastpath_timer_check(tsk
))
1150 if (!lock_task_sighand(tsk
, &flags
))
1153 * Here we take off tsk->signal->cpu_timers[N] and
1154 * tsk->cpu_timers[N] all the timers that are firing, and
1155 * put them on the firing list.
1157 check_thread_timers(tsk
, &firing
);
1159 * If there are any active process wide timers (POSIX 1.b, itimers,
1160 * RLIMIT_CPU) cputimer must be running.
1162 if (tsk
->signal
->cputimer
.running
)
1163 check_process_timers(tsk
, &firing
);
1166 * We must release these locks before taking any timer's lock.
1167 * There is a potential race with timer deletion here, as the
1168 * siglock now protects our private firing list. We have set
1169 * the firing flag in each timer, so that a deletion attempt
1170 * that gets the timer lock before we do will give it up and
1171 * spin until we've taken care of that timer below.
1173 unlock_task_sighand(tsk
, &flags
);
1176 * Now that all the timers on our list have the firing flag,
1177 * no one will touch their list entries but us. We'll take
1178 * each timer's lock before clearing its firing flag, so no
1179 * timer call will interfere.
1181 list_for_each_entry_safe(timer
, next
, &firing
, it
.cpu
.entry
) {
1184 spin_lock(&timer
->it_lock
);
1185 list_del_init(&timer
->it
.cpu
.entry
);
1186 cpu_firing
= timer
->it
.cpu
.firing
;
1187 timer
->it
.cpu
.firing
= 0;
1189 * The firing flag is -1 if we collided with a reset
1190 * of the timer, which already reported this
1191 * almost-firing as an overrun. So don't generate an event.
1193 if (likely(cpu_firing
>= 0))
1194 cpu_timer_fire(timer
);
1195 spin_unlock(&timer
->it_lock
);
1200 * Set one of the process-wide special case CPU timers or RLIMIT_CPU.
1201 * The tsk->sighand->siglock must be held by the caller.
1203 void set_process_cpu_timer(struct task_struct
*tsk
, unsigned int clock_idx
,
1204 cputime_t
*newval
, cputime_t
*oldval
)
1206 unsigned long long now
;
1208 BUG_ON(clock_idx
== CPUCLOCK_SCHED
);
1209 cpu_timer_sample_group(clock_idx
, tsk
, &now
);
1213 * We are setting itimer. The *oldval is absolute and we update
1214 * it to be relative, *newval argument is relative and we update
1215 * it to be absolute.
1218 if (*oldval
<= now
) {
1219 /* Just about to fire. */
1220 *oldval
= cputime_one_jiffy
;
1232 * Update expiration cache if we are the earliest timer, or eventually
1233 * RLIMIT_CPU limit is earlier than prof_exp cpu timer expire.
1235 switch (clock_idx
) {
1237 if (expires_gt(tsk
->signal
->cputime_expires
.prof_exp
, *newval
))
1238 tsk
->signal
->cputime_expires
.prof_exp
= *newval
;
1241 if (expires_gt(tsk
->signal
->cputime_expires
.virt_exp
, *newval
))
1242 tsk
->signal
->cputime_expires
.virt_exp
= *newval
;
1246 posix_cpu_timer_kick_nohz();
1249 static int do_cpu_nanosleep(const clockid_t which_clock
, int flags
,
1250 struct timespec
*rqtp
, struct itimerspec
*it
)
1252 struct k_itimer timer
;
1256 * Set up a temporary timer and then wait for it to go off.
1258 memset(&timer
, 0, sizeof timer
);
1259 spin_lock_init(&timer
.it_lock
);
1260 timer
.it_clock
= which_clock
;
1261 timer
.it_overrun
= -1;
1262 error
= posix_cpu_timer_create(&timer
);
1263 timer
.it_process
= current
;
1265 static struct itimerspec zero_it
;
1267 memset(it
, 0, sizeof *it
);
1268 it
->it_value
= *rqtp
;
1270 spin_lock_irq(&timer
.it_lock
);
1271 error
= posix_cpu_timer_set(&timer
, flags
, it
, NULL
);
1273 spin_unlock_irq(&timer
.it_lock
);
1277 while (!signal_pending(current
)) {
1278 if (timer
.it
.cpu
.expires
== 0) {
1280 * Our timer fired and was reset, below
1281 * deletion can not fail.
1283 posix_cpu_timer_del(&timer
);
1284 spin_unlock_irq(&timer
.it_lock
);
1289 * Block until cpu_timer_fire (or a signal) wakes us.
1291 __set_current_state(TASK_INTERRUPTIBLE
);
1292 spin_unlock_irq(&timer
.it_lock
);
1294 spin_lock_irq(&timer
.it_lock
);
1298 * We were interrupted by a signal.
1300 sample_to_timespec(which_clock
, timer
.it
.cpu
.expires
, rqtp
);
1301 error
= posix_cpu_timer_set(&timer
, 0, &zero_it
, it
);
1304 * Timer is now unarmed, deletion can not fail.
1306 posix_cpu_timer_del(&timer
);
1308 spin_unlock_irq(&timer
.it_lock
);
1310 while (error
== TIMER_RETRY
) {
1312 * We need to handle case when timer was or is in the
1313 * middle of firing. In other cases we already freed
1316 spin_lock_irq(&timer
.it_lock
);
1317 error
= posix_cpu_timer_del(&timer
);
1318 spin_unlock_irq(&timer
.it_lock
);
1321 if ((it
->it_value
.tv_sec
| it
->it_value
.tv_nsec
) == 0) {
1323 * It actually did fire already.
1328 error
= -ERESTART_RESTARTBLOCK
;
1334 static long posix_cpu_nsleep_restart(struct restart_block
*restart_block
);
1336 static int posix_cpu_nsleep(const clockid_t which_clock
, int flags
,
1337 struct timespec
*rqtp
, struct timespec __user
*rmtp
)
1339 struct restart_block
*restart_block
=
1340 ¤t_thread_info()->restart_block
;
1341 struct itimerspec it
;
1345 * Diagnose required errors first.
1347 if (CPUCLOCK_PERTHREAD(which_clock
) &&
1348 (CPUCLOCK_PID(which_clock
) == 0 ||
1349 CPUCLOCK_PID(which_clock
) == current
->pid
))
1352 error
= do_cpu_nanosleep(which_clock
, flags
, rqtp
, &it
);
1354 if (error
== -ERESTART_RESTARTBLOCK
) {
1356 if (flags
& TIMER_ABSTIME
)
1357 return -ERESTARTNOHAND
;
1359 * Report back to the user the time still remaining.
1361 if (rmtp
&& copy_to_user(rmtp
, &it
.it_value
, sizeof *rmtp
))
1364 restart_block
->fn
= posix_cpu_nsleep_restart
;
1365 restart_block
->nanosleep
.clockid
= which_clock
;
1366 restart_block
->nanosleep
.rmtp
= rmtp
;
1367 restart_block
->nanosleep
.expires
= timespec_to_ns(rqtp
);
1372 static long posix_cpu_nsleep_restart(struct restart_block
*restart_block
)
1374 clockid_t which_clock
= restart_block
->nanosleep
.clockid
;
1376 struct itimerspec it
;
1379 t
= ns_to_timespec(restart_block
->nanosleep
.expires
);
1381 error
= do_cpu_nanosleep(which_clock
, TIMER_ABSTIME
, &t
, &it
);
1383 if (error
== -ERESTART_RESTARTBLOCK
) {
1384 struct timespec __user
*rmtp
= restart_block
->nanosleep
.rmtp
;
1386 * Report back to the user the time still remaining.
1388 if (rmtp
&& copy_to_user(rmtp
, &it
.it_value
, sizeof *rmtp
))
1391 restart_block
->nanosleep
.expires
= timespec_to_ns(&t
);
1397 #define PROCESS_CLOCK MAKE_PROCESS_CPUCLOCK(0, CPUCLOCK_SCHED)
1398 #define THREAD_CLOCK MAKE_THREAD_CPUCLOCK(0, CPUCLOCK_SCHED)
1400 static int process_cpu_clock_getres(const clockid_t which_clock
,
1401 struct timespec
*tp
)
1403 return posix_cpu_clock_getres(PROCESS_CLOCK
, tp
);
1405 static int process_cpu_clock_get(const clockid_t which_clock
,
1406 struct timespec
*tp
)
1408 return posix_cpu_clock_get(PROCESS_CLOCK
, tp
);
1410 static int process_cpu_timer_create(struct k_itimer
*timer
)
1412 timer
->it_clock
= PROCESS_CLOCK
;
1413 return posix_cpu_timer_create(timer
);
1415 static int process_cpu_nsleep(const clockid_t which_clock
, int flags
,
1416 struct timespec
*rqtp
,
1417 struct timespec __user
*rmtp
)
1419 return posix_cpu_nsleep(PROCESS_CLOCK
, flags
, rqtp
, rmtp
);
1421 static long process_cpu_nsleep_restart(struct restart_block
*restart_block
)
1425 static int thread_cpu_clock_getres(const clockid_t which_clock
,
1426 struct timespec
*tp
)
1428 return posix_cpu_clock_getres(THREAD_CLOCK
, tp
);
1430 static int thread_cpu_clock_get(const clockid_t which_clock
,
1431 struct timespec
*tp
)
1433 return posix_cpu_clock_get(THREAD_CLOCK
, tp
);
1435 static int thread_cpu_timer_create(struct k_itimer
*timer
)
1437 timer
->it_clock
= THREAD_CLOCK
;
1438 return posix_cpu_timer_create(timer
);
1441 struct k_clock clock_posix_cpu
= {
1442 .clock_getres
= posix_cpu_clock_getres
,
1443 .clock_set
= posix_cpu_clock_set
,
1444 .clock_get
= posix_cpu_clock_get
,
1445 .timer_create
= posix_cpu_timer_create
,
1446 .nsleep
= posix_cpu_nsleep
,
1447 .nsleep_restart
= posix_cpu_nsleep_restart
,
1448 .timer_set
= posix_cpu_timer_set
,
1449 .timer_del
= posix_cpu_timer_del
,
1450 .timer_get
= posix_cpu_timer_get
,
1453 static __init
int init_posix_cpu_timers(void)
1455 struct k_clock process
= {
1456 .clock_getres
= process_cpu_clock_getres
,
1457 .clock_get
= process_cpu_clock_get
,
1458 .timer_create
= process_cpu_timer_create
,
1459 .nsleep
= process_cpu_nsleep
,
1460 .nsleep_restart
= process_cpu_nsleep_restart
,
1462 struct k_clock thread
= {
1463 .clock_getres
= thread_cpu_clock_getres
,
1464 .clock_get
= thread_cpu_clock_get
,
1465 .timer_create
= thread_cpu_timer_create
,
1469 posix_timers_register_clock(CLOCK_PROCESS_CPUTIME_ID
, &process
);
1470 posix_timers_register_clock(CLOCK_THREAD_CPUTIME_ID
, &thread
);
1472 cputime_to_timespec(cputime_one_jiffy
, &ts
);
1473 onecputick
= ts
.tv_nsec
;
1474 WARN_ON(ts
.tv_sec
!= 0);
1478 __initcall(init_posix_cpu_timers
);