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 task sighand lock held for safe while_each_thread()
239 static int cpu_clock_sample_group(const clockid_t which_clock
,
240 struct task_struct
*p
,
241 unsigned long long *sample
)
243 struct task_cputime cputime
;
245 switch (CPUCLOCK_WHICH(which_clock
)) {
249 thread_group_cputime(p
, &cputime
);
250 *sample
= cputime_to_expires(cputime
.utime
+ cputime
.stime
);
253 thread_group_cputime(p
, &cputime
);
254 *sample
= cputime_to_expires(cputime
.utime
);
257 thread_group_cputime(p
, &cputime
);
258 *sample
= cputime
.sum_exec_runtime
;
264 static int posix_cpu_clock_get_task(struct task_struct
*tsk
,
265 const clockid_t which_clock
,
269 unsigned long long rtn
;
271 if (CPUCLOCK_PERTHREAD(which_clock
)) {
272 if (same_thread_group(tsk
, current
))
273 err
= cpu_clock_sample(which_clock
, tsk
, &rtn
);
275 if (tsk
== current
|| thread_group_leader(tsk
))
276 err
= cpu_clock_sample_group(which_clock
, tsk
, &rtn
);
280 sample_to_timespec(which_clock
, rtn
, tp
);
286 static int posix_cpu_clock_get(const clockid_t which_clock
, struct timespec
*tp
)
288 const pid_t pid
= CPUCLOCK_PID(which_clock
);
293 * Special case constant value for our own clocks.
294 * We don't have to do any lookup to find ourselves.
296 err
= posix_cpu_clock_get_task(current
, which_clock
, tp
);
299 * Find the given PID, and validate that the caller
300 * should be able to see it.
302 struct task_struct
*p
;
304 p
= find_task_by_vpid(pid
);
306 err
= posix_cpu_clock_get_task(p
, which_clock
, tp
);
315 * Validate the clockid_t for a new CPU-clock timer, and initialize the timer.
316 * This is called from sys_timer_create() and do_cpu_nanosleep() with the
317 * new timer already all-zeros initialized.
319 static int posix_cpu_timer_create(struct k_itimer
*new_timer
)
322 const pid_t pid
= CPUCLOCK_PID(new_timer
->it_clock
);
323 struct task_struct
*p
;
325 if (CPUCLOCK_WHICH(new_timer
->it_clock
) >= CPUCLOCK_MAX
)
328 INIT_LIST_HEAD(&new_timer
->it
.cpu
.entry
);
331 if (CPUCLOCK_PERTHREAD(new_timer
->it_clock
)) {
335 p
= find_task_by_vpid(pid
);
336 if (p
&& !same_thread_group(p
, current
))
341 p
= current
->group_leader
;
343 p
= find_task_by_vpid(pid
);
344 if (p
&& !has_group_leader_pid(p
))
348 new_timer
->it
.cpu
.task
= p
;
360 * Clean up a CPU-clock timer that is about to be destroyed.
361 * This is called from timer deletion with the timer already locked.
362 * If we return TIMER_RETRY, it's necessary to release the timer's lock
363 * and try again. (This happens when the timer is in the middle of firing.)
365 static int posix_cpu_timer_del(struct k_itimer
*timer
)
369 struct sighand_struct
*sighand
;
370 struct task_struct
*p
= timer
->it
.cpu
.task
;
372 WARN_ON_ONCE(p
== NULL
);
375 * Protect against sighand release/switch in exit/exec and process/
376 * thread timer list entry concurrent read/writes.
378 sighand
= lock_task_sighand(p
, &flags
);
379 if (unlikely(sighand
== NULL
)) {
381 * We raced with the reaping of the task.
382 * The deletion should have cleared us off the list.
384 WARN_ON_ONCE(!list_empty(&timer
->it
.cpu
.entry
));
386 if (timer
->it
.cpu
.firing
)
389 list_del(&timer
->it
.cpu
.entry
);
391 unlock_task_sighand(p
, &flags
);
400 static void cleanup_timers_list(struct list_head
*head
)
402 struct cpu_timer_list
*timer
, *next
;
404 list_for_each_entry_safe(timer
, next
, head
, entry
)
405 list_del_init(&timer
->entry
);
409 * Clean out CPU timers still ticking when a thread exited. The task
410 * pointer is cleared, and the expiry time is replaced with the residual
411 * time for later timer_gettime calls to return.
412 * This must be called with the siglock held.
414 static void cleanup_timers(struct list_head
*head
)
416 cleanup_timers_list(head
);
417 cleanup_timers_list(++head
);
418 cleanup_timers_list(++head
);
422 * These are both called with the siglock held, when the current thread
423 * is being reaped. When the final (leader) thread in the group is reaped,
424 * posix_cpu_timers_exit_group will be called after posix_cpu_timers_exit.
426 void posix_cpu_timers_exit(struct task_struct
*tsk
)
428 add_device_randomness((const void*) &tsk
->se
.sum_exec_runtime
,
429 sizeof(unsigned long long));
430 cleanup_timers(tsk
->cpu_timers
);
433 void posix_cpu_timers_exit_group(struct task_struct
*tsk
)
435 cleanup_timers(tsk
->signal
->cpu_timers
);
438 static inline int expires_gt(cputime_t expires
, cputime_t new_exp
)
440 return expires
== 0 || expires
> new_exp
;
444 * Insert the timer on the appropriate list before any timers that
445 * expire later. This must be called with the sighand lock held.
447 static void arm_timer(struct k_itimer
*timer
)
449 struct task_struct
*p
= timer
->it
.cpu
.task
;
450 struct list_head
*head
, *listpos
;
451 struct task_cputime
*cputime_expires
;
452 struct cpu_timer_list
*const nt
= &timer
->it
.cpu
;
453 struct cpu_timer_list
*next
;
455 if (CPUCLOCK_PERTHREAD(timer
->it_clock
)) {
456 head
= p
->cpu_timers
;
457 cputime_expires
= &p
->cputime_expires
;
459 head
= p
->signal
->cpu_timers
;
460 cputime_expires
= &p
->signal
->cputime_expires
;
462 head
+= CPUCLOCK_WHICH(timer
->it_clock
);
465 list_for_each_entry(next
, head
, entry
) {
466 if (nt
->expires
< next
->expires
)
468 listpos
= &next
->entry
;
470 list_add(&nt
->entry
, listpos
);
472 if (listpos
== head
) {
473 unsigned long long exp
= nt
->expires
;
476 * We are the new earliest-expiring POSIX 1.b timer, hence
477 * need to update expiration cache. Take into account that
478 * for process timers we share expiration cache with itimers
479 * and RLIMIT_CPU and for thread timers with RLIMIT_RTTIME.
482 switch (CPUCLOCK_WHICH(timer
->it_clock
)) {
484 if (expires_gt(cputime_expires
->prof_exp
, expires_to_cputime(exp
)))
485 cputime_expires
->prof_exp
= expires_to_cputime(exp
);
488 if (expires_gt(cputime_expires
->virt_exp
, expires_to_cputime(exp
)))
489 cputime_expires
->virt_exp
= expires_to_cputime(exp
);
492 if (cputime_expires
->sched_exp
== 0 ||
493 cputime_expires
->sched_exp
> exp
)
494 cputime_expires
->sched_exp
= exp
;
501 * The timer is locked, fire it and arrange for its reload.
503 static void cpu_timer_fire(struct k_itimer
*timer
)
505 if ((timer
->it_sigev_notify
& ~SIGEV_THREAD_ID
) == SIGEV_NONE
) {
507 * User don't want any signal.
509 timer
->it
.cpu
.expires
= 0;
510 } else if (unlikely(timer
->sigq
== NULL
)) {
512 * This a special case for clock_nanosleep,
513 * not a normal timer from sys_timer_create.
515 wake_up_process(timer
->it_process
);
516 timer
->it
.cpu
.expires
= 0;
517 } else if (timer
->it
.cpu
.incr
== 0) {
519 * One-shot timer. Clear it as soon as it's fired.
521 posix_timer_event(timer
, 0);
522 timer
->it
.cpu
.expires
= 0;
523 } else if (posix_timer_event(timer
, ++timer
->it_requeue_pending
)) {
525 * The signal did not get queued because the signal
526 * was ignored, so we won't get any callback to
527 * reload the timer. But we need to keep it
528 * ticking in case the signal is deliverable next time.
530 posix_cpu_timer_schedule(timer
);
535 * Sample a process (thread group) timer for the given group_leader task.
536 * Must be called with task sighand lock held for safe while_each_thread()
539 static int cpu_timer_sample_group(const clockid_t which_clock
,
540 struct task_struct
*p
,
541 unsigned long long *sample
)
543 struct task_cputime cputime
;
545 thread_group_cputimer(p
, &cputime
);
546 switch (CPUCLOCK_WHICH(which_clock
)) {
550 *sample
= cputime_to_expires(cputime
.utime
+ cputime
.stime
);
553 *sample
= cputime_to_expires(cputime
.utime
);
556 *sample
= cputime
.sum_exec_runtime
;
562 #ifdef CONFIG_NO_HZ_FULL
563 static void nohz_kick_work_fn(struct work_struct
*work
)
565 tick_nohz_full_kick_all();
568 static DECLARE_WORK(nohz_kick_work
, nohz_kick_work_fn
);
571 * We need the IPIs to be sent from sane process context.
572 * The posix cpu timers are always set with irqs disabled.
574 static void posix_cpu_timer_kick_nohz(void)
576 if (context_tracking_is_enabled())
577 schedule_work(&nohz_kick_work
);
580 bool posix_cpu_timers_can_stop_tick(struct task_struct
*tsk
)
582 if (!task_cputime_zero(&tsk
->cputime_expires
))
585 if (tsk
->signal
->cputimer
.running
)
591 static inline void posix_cpu_timer_kick_nohz(void) { }
595 * Guts of sys_timer_settime for CPU timers.
596 * This is called with the timer locked and interrupts disabled.
597 * If we return TIMER_RETRY, it's necessary to release the timer's lock
598 * and try again. (This happens when the timer is in the middle of firing.)
600 static int posix_cpu_timer_set(struct k_itimer
*timer
, int timer_flags
,
601 struct itimerspec
*new, struct itimerspec
*old
)
604 struct sighand_struct
*sighand
;
605 struct task_struct
*p
= timer
->it
.cpu
.task
;
606 unsigned long long old_expires
, new_expires
, old_incr
, val
;
609 WARN_ON_ONCE(p
== NULL
);
611 new_expires
= timespec_to_sample(timer
->it_clock
, &new->it_value
);
614 * Protect against sighand release/switch in exit/exec and p->cpu_timers
615 * and p->signal->cpu_timers read/write in arm_timer()
617 sighand
= lock_task_sighand(p
, &flags
);
619 * If p has just been reaped, we can no
620 * longer get any information about it at all.
622 if (unlikely(sighand
== NULL
)) {
627 * Disarm any old timer after extracting its expiry time.
629 WARN_ON_ONCE(!irqs_disabled());
632 old_incr
= timer
->it
.cpu
.incr
;
633 old_expires
= timer
->it
.cpu
.expires
;
634 if (unlikely(timer
->it
.cpu
.firing
)) {
635 timer
->it
.cpu
.firing
= -1;
638 list_del_init(&timer
->it
.cpu
.entry
);
641 * We need to sample the current value to convert the new
642 * value from to relative and absolute, and to convert the
643 * old value from absolute to relative. To set a process
644 * timer, we need a sample to balance the thread expiry
645 * times (in arm_timer). With an absolute time, we must
646 * check if it's already passed. In short, we need a sample.
648 if (CPUCLOCK_PERTHREAD(timer
->it_clock
)) {
649 cpu_clock_sample(timer
->it_clock
, p
, &val
);
651 cpu_timer_sample_group(timer
->it_clock
, p
, &val
);
655 if (old_expires
== 0) {
656 old
->it_value
.tv_sec
= 0;
657 old
->it_value
.tv_nsec
= 0;
660 * Update the timer in case it has
661 * overrun already. If it has,
662 * we'll report it as having overrun
663 * and with the next reloaded timer
664 * already ticking, though we are
665 * swallowing that pending
666 * notification here to install the
669 bump_cpu_timer(timer
, val
);
670 if (val
< timer
->it
.cpu
.expires
) {
671 old_expires
= timer
->it
.cpu
.expires
- val
;
672 sample_to_timespec(timer
->it_clock
,
676 old
->it_value
.tv_nsec
= 1;
677 old
->it_value
.tv_sec
= 0;
684 * We are colliding with the timer actually firing.
685 * Punt after filling in the timer's old value, and
686 * disable this firing since we are already reporting
687 * it as an overrun (thanks to bump_cpu_timer above).
689 unlock_task_sighand(p
, &flags
);
693 if (new_expires
!= 0 && !(timer_flags
& TIMER_ABSTIME
)) {
698 * Install the new expiry time (or zero).
699 * For a timer with no notification action, we don't actually
700 * arm the timer (we'll just fake it for timer_gettime).
702 timer
->it
.cpu
.expires
= new_expires
;
703 if (new_expires
!= 0 && val
< new_expires
) {
707 unlock_task_sighand(p
, &flags
);
709 * Install the new reload setting, and
710 * set up the signal and overrun bookkeeping.
712 timer
->it
.cpu
.incr
= timespec_to_sample(timer
->it_clock
,
716 * This acts as a modification timestamp for the timer,
717 * so any automatic reload attempt will punt on seeing
718 * that we have reset the timer manually.
720 timer
->it_requeue_pending
= (timer
->it_requeue_pending
+ 2) &
722 timer
->it_overrun_last
= 0;
723 timer
->it_overrun
= -1;
725 if (new_expires
!= 0 && !(val
< new_expires
)) {
727 * The designated time already passed, so we notify
728 * immediately, even if the thread never runs to
729 * accumulate more time on this clock.
731 cpu_timer_fire(timer
);
737 sample_to_timespec(timer
->it_clock
,
738 old_incr
, &old
->it_interval
);
741 posix_cpu_timer_kick_nohz();
745 static void posix_cpu_timer_get(struct k_itimer
*timer
, struct itimerspec
*itp
)
747 unsigned long long now
;
748 struct task_struct
*p
= timer
->it
.cpu
.task
;
750 WARN_ON_ONCE(p
== NULL
);
753 * Easy part: convert the reload time.
755 sample_to_timespec(timer
->it_clock
,
756 timer
->it
.cpu
.incr
, &itp
->it_interval
);
758 if (timer
->it
.cpu
.expires
== 0) { /* Timer not armed at all. */
759 itp
->it_value
.tv_sec
= itp
->it_value
.tv_nsec
= 0;
764 * Sample the clock to take the difference with the expiry time.
766 if (CPUCLOCK_PERTHREAD(timer
->it_clock
)) {
767 cpu_clock_sample(timer
->it_clock
, p
, &now
);
769 struct sighand_struct
*sighand
;
773 * Protect against sighand release/switch in exit/exec and
774 * also make timer sampling safe if it ends up calling
775 * thread_group_cputime().
777 sighand
= lock_task_sighand(p
, &flags
);
778 if (unlikely(sighand
== NULL
)) {
780 * The process has been reaped.
781 * We can't even collect a sample any more.
782 * Call the timer disarmed, nothing else to do.
784 timer
->it
.cpu
.expires
= 0;
785 sample_to_timespec(timer
->it_clock
, timer
->it
.cpu
.expires
,
788 cpu_timer_sample_group(timer
->it_clock
, p
, &now
);
789 unlock_task_sighand(p
, &flags
);
793 if (now
< timer
->it
.cpu
.expires
) {
794 sample_to_timespec(timer
->it_clock
,
795 timer
->it
.cpu
.expires
- now
,
799 * The timer should have expired already, but the firing
800 * hasn't taken place yet. Say it's just about to expire.
802 itp
->it_value
.tv_nsec
= 1;
803 itp
->it_value
.tv_sec
= 0;
807 static unsigned long long
808 check_timers_list(struct list_head
*timers
,
809 struct list_head
*firing
,
810 unsigned long long curr
)
814 while (!list_empty(timers
)) {
815 struct cpu_timer_list
*t
;
817 t
= list_first_entry(timers
, struct cpu_timer_list
, entry
);
819 if (!--maxfire
|| curr
< t
->expires
)
823 list_move_tail(&t
->entry
, firing
);
830 * Check for any per-thread CPU timers that have fired and move them off
831 * the tsk->cpu_timers[N] list onto the firing list. Here we update the
832 * tsk->it_*_expires values to reflect the remaining thread CPU timers.
834 static void check_thread_timers(struct task_struct
*tsk
,
835 struct list_head
*firing
)
837 struct list_head
*timers
= tsk
->cpu_timers
;
838 struct signal_struct
*const sig
= tsk
->signal
;
839 struct task_cputime
*tsk_expires
= &tsk
->cputime_expires
;
840 unsigned long long expires
;
843 expires
= check_timers_list(timers
, firing
, prof_ticks(tsk
));
844 tsk_expires
->prof_exp
= expires_to_cputime(expires
);
846 expires
= check_timers_list(++timers
, firing
, virt_ticks(tsk
));
847 tsk_expires
->virt_exp
= expires_to_cputime(expires
);
849 tsk_expires
->sched_exp
= check_timers_list(++timers
, firing
,
850 tsk
->se
.sum_exec_runtime
);
853 * Check for the special case thread timers.
855 soft
= ACCESS_ONCE(sig
->rlim
[RLIMIT_RTTIME
].rlim_cur
);
856 if (soft
!= RLIM_INFINITY
) {
858 ACCESS_ONCE(sig
->rlim
[RLIMIT_RTTIME
].rlim_max
);
860 if (hard
!= RLIM_INFINITY
&&
861 tsk
->rt
.timeout
> DIV_ROUND_UP(hard
, USEC_PER_SEC
/HZ
)) {
863 * At the hard limit, we just die.
864 * No need to calculate anything else now.
866 __group_send_sig_info(SIGKILL
, SEND_SIG_PRIV
, tsk
);
869 if (tsk
->rt
.timeout
> DIV_ROUND_UP(soft
, USEC_PER_SEC
/HZ
)) {
871 * At the soft limit, send a SIGXCPU every second.
874 soft
+= USEC_PER_SEC
;
875 sig
->rlim
[RLIMIT_RTTIME
].rlim_cur
= soft
;
878 "RT Watchdog Timeout: %s[%d]\n",
879 tsk
->comm
, task_pid_nr(tsk
));
880 __group_send_sig_info(SIGXCPU
, SEND_SIG_PRIV
, tsk
);
885 static void stop_process_timers(struct signal_struct
*sig
)
887 struct thread_group_cputimer
*cputimer
= &sig
->cputimer
;
890 raw_spin_lock_irqsave(&cputimer
->lock
, flags
);
891 cputimer
->running
= 0;
892 raw_spin_unlock_irqrestore(&cputimer
->lock
, flags
);
895 static u32 onecputick
;
897 static void check_cpu_itimer(struct task_struct
*tsk
, struct cpu_itimer
*it
,
898 unsigned long long *expires
,
899 unsigned long long cur_time
, int signo
)
904 if (cur_time
>= it
->expires
) {
906 it
->expires
+= it
->incr
;
907 it
->error
+= it
->incr_error
;
908 if (it
->error
>= onecputick
) {
909 it
->expires
-= cputime_one_jiffy
;
910 it
->error
-= onecputick
;
916 trace_itimer_expire(signo
== SIGPROF
?
917 ITIMER_PROF
: ITIMER_VIRTUAL
,
918 tsk
->signal
->leader_pid
, cur_time
);
919 __group_send_sig_info(signo
, SEND_SIG_PRIV
, tsk
);
922 if (it
->expires
&& (!*expires
|| it
->expires
< *expires
)) {
923 *expires
= it
->expires
;
928 * Check for any per-thread CPU timers that have fired and move them
929 * off the tsk->*_timers list onto the firing list. Per-thread timers
930 * have already been taken off.
932 static void check_process_timers(struct task_struct
*tsk
,
933 struct list_head
*firing
)
935 struct signal_struct
*const sig
= tsk
->signal
;
936 unsigned long long utime
, ptime
, virt_expires
, prof_expires
;
937 unsigned long long sum_sched_runtime
, sched_expires
;
938 struct list_head
*timers
= sig
->cpu_timers
;
939 struct task_cputime cputime
;
943 * Collect the current process totals.
945 thread_group_cputimer(tsk
, &cputime
);
946 utime
= cputime_to_expires(cputime
.utime
);
947 ptime
= utime
+ cputime_to_expires(cputime
.stime
);
948 sum_sched_runtime
= cputime
.sum_exec_runtime
;
950 prof_expires
= check_timers_list(timers
, firing
, ptime
);
951 virt_expires
= check_timers_list(++timers
, firing
, utime
);
952 sched_expires
= check_timers_list(++timers
, firing
, sum_sched_runtime
);
955 * Check for the special case process timers.
957 check_cpu_itimer(tsk
, &sig
->it
[CPUCLOCK_PROF
], &prof_expires
, ptime
,
959 check_cpu_itimer(tsk
, &sig
->it
[CPUCLOCK_VIRT
], &virt_expires
, utime
,
961 soft
= ACCESS_ONCE(sig
->rlim
[RLIMIT_CPU
].rlim_cur
);
962 if (soft
!= RLIM_INFINITY
) {
963 unsigned long psecs
= cputime_to_secs(ptime
);
965 ACCESS_ONCE(sig
->rlim
[RLIMIT_CPU
].rlim_max
);
969 * At the hard limit, we just die.
970 * No need to calculate anything else now.
972 __group_send_sig_info(SIGKILL
, SEND_SIG_PRIV
, tsk
);
977 * At the soft limit, send a SIGXCPU every second.
979 __group_send_sig_info(SIGXCPU
, SEND_SIG_PRIV
, tsk
);
982 sig
->rlim
[RLIMIT_CPU
].rlim_cur
= soft
;
985 x
= secs_to_cputime(soft
);
986 if (!prof_expires
|| x
< prof_expires
) {
991 sig
->cputime_expires
.prof_exp
= expires_to_cputime(prof_expires
);
992 sig
->cputime_expires
.virt_exp
= expires_to_cputime(virt_expires
);
993 sig
->cputime_expires
.sched_exp
= sched_expires
;
994 if (task_cputime_zero(&sig
->cputime_expires
))
995 stop_process_timers(sig
);
999 * This is called from the signal code (via do_schedule_next_timer)
1000 * when the last timer signal was delivered and we have to reload the timer.
1002 void posix_cpu_timer_schedule(struct k_itimer
*timer
)
1004 struct sighand_struct
*sighand
;
1005 unsigned long flags
;
1006 struct task_struct
*p
= timer
->it
.cpu
.task
;
1007 unsigned long long now
;
1009 WARN_ON_ONCE(p
== NULL
);
1012 * Fetch the current sample and update the timer's expiry time.
1014 if (CPUCLOCK_PERTHREAD(timer
->it_clock
)) {
1015 cpu_clock_sample(timer
->it_clock
, p
, &now
);
1016 bump_cpu_timer(timer
, now
);
1017 if (unlikely(p
->exit_state
))
1020 /* Protect timer list r/w in arm_timer() */
1021 sighand
= lock_task_sighand(p
, &flags
);
1026 * Protect arm_timer() and timer sampling in case of call to
1027 * thread_group_cputime().
1029 sighand
= lock_task_sighand(p
, &flags
);
1030 if (unlikely(sighand
== NULL
)) {
1032 * The process has been reaped.
1033 * We can't even collect a sample any more.
1035 timer
->it
.cpu
.expires
= 0;
1037 } else if (unlikely(p
->exit_state
) && thread_group_empty(p
)) {
1038 unlock_task_sighand(p
, &flags
);
1039 /* Optimizations: if the process is dying, no need to rearm */
1042 cpu_timer_sample_group(timer
->it_clock
, p
, &now
);
1043 bump_cpu_timer(timer
, now
);
1044 /* Leave the sighand locked for the call below. */
1048 * Now re-arm for the new expiry time.
1050 WARN_ON_ONCE(!irqs_disabled());
1052 unlock_task_sighand(p
, &flags
);
1054 /* Kick full dynticks CPUs in case they need to tick on the new timer */
1055 posix_cpu_timer_kick_nohz();
1057 timer
->it_overrun_last
= timer
->it_overrun
;
1058 timer
->it_overrun
= -1;
1059 ++timer
->it_requeue_pending
;
1063 * task_cputime_expired - Compare two task_cputime entities.
1065 * @sample: The task_cputime structure to be checked for expiration.
1066 * @expires: Expiration times, against which @sample will be checked.
1068 * Checks @sample against @expires to see if any field of @sample has expired.
1069 * Returns true if any field of the former is greater than the corresponding
1070 * field of the latter if the latter field is set. Otherwise returns false.
1072 static inline int task_cputime_expired(const struct task_cputime
*sample
,
1073 const struct task_cputime
*expires
)
1075 if (expires
->utime
&& sample
->utime
>= expires
->utime
)
1077 if (expires
->stime
&& sample
->utime
+ sample
->stime
>= expires
->stime
)
1079 if (expires
->sum_exec_runtime
!= 0 &&
1080 sample
->sum_exec_runtime
>= expires
->sum_exec_runtime
)
1086 * fastpath_timer_check - POSIX CPU timers fast path.
1088 * @tsk: The task (thread) being checked.
1090 * Check the task and thread group timers. If both are zero (there are no
1091 * timers set) return false. Otherwise snapshot the task and thread group
1092 * timers and compare them with the corresponding expiration times. Return
1093 * true if a timer has expired, else return false.
1095 static inline int fastpath_timer_check(struct task_struct
*tsk
)
1097 struct signal_struct
*sig
;
1098 cputime_t utime
, stime
;
1100 task_cputime(tsk
, &utime
, &stime
);
1102 if (!task_cputime_zero(&tsk
->cputime_expires
)) {
1103 struct task_cputime task_sample
= {
1106 .sum_exec_runtime
= tsk
->se
.sum_exec_runtime
1109 if (task_cputime_expired(&task_sample
, &tsk
->cputime_expires
))
1114 if (sig
->cputimer
.running
) {
1115 struct task_cputime group_sample
;
1117 raw_spin_lock(&sig
->cputimer
.lock
);
1118 group_sample
= sig
->cputimer
.cputime
;
1119 raw_spin_unlock(&sig
->cputimer
.lock
);
1121 if (task_cputime_expired(&group_sample
, &sig
->cputime_expires
))
1129 * This is called from the timer interrupt handler. The irq handler has
1130 * already updated our counts. We need to check if any timers fire now.
1131 * Interrupts are disabled.
1133 void run_posix_cpu_timers(struct task_struct
*tsk
)
1136 struct k_itimer
*timer
, *next
;
1137 unsigned long flags
;
1139 WARN_ON_ONCE(!irqs_disabled());
1142 * The fast path checks that there are no expired thread or thread
1143 * group timers. If that's so, just return.
1145 if (!fastpath_timer_check(tsk
))
1148 if (!lock_task_sighand(tsk
, &flags
))
1151 * Here we take off tsk->signal->cpu_timers[N] and
1152 * tsk->cpu_timers[N] all the timers that are firing, and
1153 * put them on the firing list.
1155 check_thread_timers(tsk
, &firing
);
1157 * If there are any active process wide timers (POSIX 1.b, itimers,
1158 * RLIMIT_CPU) cputimer must be running.
1160 if (tsk
->signal
->cputimer
.running
)
1161 check_process_timers(tsk
, &firing
);
1164 * We must release these locks before taking any timer's lock.
1165 * There is a potential race with timer deletion here, as the
1166 * siglock now protects our private firing list. We have set
1167 * the firing flag in each timer, so that a deletion attempt
1168 * that gets the timer lock before we do will give it up and
1169 * spin until we've taken care of that timer below.
1171 unlock_task_sighand(tsk
, &flags
);
1174 * Now that all the timers on our list have the firing flag,
1175 * no one will touch their list entries but us. We'll take
1176 * each timer's lock before clearing its firing flag, so no
1177 * timer call will interfere.
1179 list_for_each_entry_safe(timer
, next
, &firing
, it
.cpu
.entry
) {
1182 spin_lock(&timer
->it_lock
);
1183 list_del_init(&timer
->it
.cpu
.entry
);
1184 cpu_firing
= timer
->it
.cpu
.firing
;
1185 timer
->it
.cpu
.firing
= 0;
1187 * The firing flag is -1 if we collided with a reset
1188 * of the timer, which already reported this
1189 * almost-firing as an overrun. So don't generate an event.
1191 if (likely(cpu_firing
>= 0))
1192 cpu_timer_fire(timer
);
1193 spin_unlock(&timer
->it_lock
);
1198 * Set one of the process-wide special case CPU timers or RLIMIT_CPU.
1199 * The tsk->sighand->siglock must be held by the caller.
1201 void set_process_cpu_timer(struct task_struct
*tsk
, unsigned int clock_idx
,
1202 cputime_t
*newval
, cputime_t
*oldval
)
1204 unsigned long long now
;
1206 WARN_ON_ONCE(clock_idx
== CPUCLOCK_SCHED
);
1207 cpu_timer_sample_group(clock_idx
, tsk
, &now
);
1211 * We are setting itimer. The *oldval is absolute and we update
1212 * it to be relative, *newval argument is relative and we update
1213 * it to be absolute.
1216 if (*oldval
<= now
) {
1217 /* Just about to fire. */
1218 *oldval
= cputime_one_jiffy
;
1230 * Update expiration cache if we are the earliest timer, or eventually
1231 * RLIMIT_CPU limit is earlier than prof_exp cpu timer expire.
1233 switch (clock_idx
) {
1235 if (expires_gt(tsk
->signal
->cputime_expires
.prof_exp
, *newval
))
1236 tsk
->signal
->cputime_expires
.prof_exp
= *newval
;
1239 if (expires_gt(tsk
->signal
->cputime_expires
.virt_exp
, *newval
))
1240 tsk
->signal
->cputime_expires
.virt_exp
= *newval
;
1244 posix_cpu_timer_kick_nohz();
1247 static int do_cpu_nanosleep(const clockid_t which_clock
, int flags
,
1248 struct timespec
*rqtp
, struct itimerspec
*it
)
1250 struct k_itimer timer
;
1254 * Set up a temporary timer and then wait for it to go off.
1256 memset(&timer
, 0, sizeof timer
);
1257 spin_lock_init(&timer
.it_lock
);
1258 timer
.it_clock
= which_clock
;
1259 timer
.it_overrun
= -1;
1260 error
= posix_cpu_timer_create(&timer
);
1261 timer
.it_process
= current
;
1263 static struct itimerspec zero_it
;
1265 memset(it
, 0, sizeof *it
);
1266 it
->it_value
= *rqtp
;
1268 spin_lock_irq(&timer
.it_lock
);
1269 error
= posix_cpu_timer_set(&timer
, flags
, it
, NULL
);
1271 spin_unlock_irq(&timer
.it_lock
);
1275 while (!signal_pending(current
)) {
1276 if (timer
.it
.cpu
.expires
== 0) {
1278 * Our timer fired and was reset, below
1279 * deletion can not fail.
1281 posix_cpu_timer_del(&timer
);
1282 spin_unlock_irq(&timer
.it_lock
);
1287 * Block until cpu_timer_fire (or a signal) wakes us.
1289 __set_current_state(TASK_INTERRUPTIBLE
);
1290 spin_unlock_irq(&timer
.it_lock
);
1292 spin_lock_irq(&timer
.it_lock
);
1296 * We were interrupted by a signal.
1298 sample_to_timespec(which_clock
, timer
.it
.cpu
.expires
, rqtp
);
1299 error
= posix_cpu_timer_set(&timer
, 0, &zero_it
, it
);
1302 * Timer is now unarmed, deletion can not fail.
1304 posix_cpu_timer_del(&timer
);
1306 spin_unlock_irq(&timer
.it_lock
);
1308 while (error
== TIMER_RETRY
) {
1310 * We need to handle case when timer was or is in the
1311 * middle of firing. In other cases we already freed
1314 spin_lock_irq(&timer
.it_lock
);
1315 error
= posix_cpu_timer_del(&timer
);
1316 spin_unlock_irq(&timer
.it_lock
);
1319 if ((it
->it_value
.tv_sec
| it
->it_value
.tv_nsec
) == 0) {
1321 * It actually did fire already.
1326 error
= -ERESTART_RESTARTBLOCK
;
1332 static long posix_cpu_nsleep_restart(struct restart_block
*restart_block
);
1334 static int posix_cpu_nsleep(const clockid_t which_clock
, int flags
,
1335 struct timespec
*rqtp
, struct timespec __user
*rmtp
)
1337 struct restart_block
*restart_block
= ¤t
->restart_block
;
1338 struct itimerspec it
;
1342 * Diagnose required errors first.
1344 if (CPUCLOCK_PERTHREAD(which_clock
) &&
1345 (CPUCLOCK_PID(which_clock
) == 0 ||
1346 CPUCLOCK_PID(which_clock
) == current
->pid
))
1349 error
= do_cpu_nanosleep(which_clock
, flags
, rqtp
, &it
);
1351 if (error
== -ERESTART_RESTARTBLOCK
) {
1353 if (flags
& TIMER_ABSTIME
)
1354 return -ERESTARTNOHAND
;
1356 * Report back to the user the time still remaining.
1358 if (rmtp
&& copy_to_user(rmtp
, &it
.it_value
, sizeof *rmtp
))
1361 restart_block
->fn
= posix_cpu_nsleep_restart
;
1362 restart_block
->nanosleep
.clockid
= which_clock
;
1363 restart_block
->nanosleep
.rmtp
= rmtp
;
1364 restart_block
->nanosleep
.expires
= timespec_to_ns(rqtp
);
1369 static long posix_cpu_nsleep_restart(struct restart_block
*restart_block
)
1371 clockid_t which_clock
= restart_block
->nanosleep
.clockid
;
1373 struct itimerspec it
;
1376 t
= ns_to_timespec(restart_block
->nanosleep
.expires
);
1378 error
= do_cpu_nanosleep(which_clock
, TIMER_ABSTIME
, &t
, &it
);
1380 if (error
== -ERESTART_RESTARTBLOCK
) {
1381 struct timespec __user
*rmtp
= restart_block
->nanosleep
.rmtp
;
1383 * Report back to the user the time still remaining.
1385 if (rmtp
&& copy_to_user(rmtp
, &it
.it_value
, sizeof *rmtp
))
1388 restart_block
->nanosleep
.expires
= timespec_to_ns(&t
);
1394 #define PROCESS_CLOCK MAKE_PROCESS_CPUCLOCK(0, CPUCLOCK_SCHED)
1395 #define THREAD_CLOCK MAKE_THREAD_CPUCLOCK(0, CPUCLOCK_SCHED)
1397 static int process_cpu_clock_getres(const clockid_t which_clock
,
1398 struct timespec
*tp
)
1400 return posix_cpu_clock_getres(PROCESS_CLOCK
, tp
);
1402 static int process_cpu_clock_get(const clockid_t which_clock
,
1403 struct timespec
*tp
)
1405 return posix_cpu_clock_get(PROCESS_CLOCK
, tp
);
1407 static int process_cpu_timer_create(struct k_itimer
*timer
)
1409 timer
->it_clock
= PROCESS_CLOCK
;
1410 return posix_cpu_timer_create(timer
);
1412 static int process_cpu_nsleep(const clockid_t which_clock
, int flags
,
1413 struct timespec
*rqtp
,
1414 struct timespec __user
*rmtp
)
1416 return posix_cpu_nsleep(PROCESS_CLOCK
, flags
, rqtp
, rmtp
);
1418 static long process_cpu_nsleep_restart(struct restart_block
*restart_block
)
1422 static int thread_cpu_clock_getres(const clockid_t which_clock
,
1423 struct timespec
*tp
)
1425 return posix_cpu_clock_getres(THREAD_CLOCK
, tp
);
1427 static int thread_cpu_clock_get(const clockid_t which_clock
,
1428 struct timespec
*tp
)
1430 return posix_cpu_clock_get(THREAD_CLOCK
, tp
);
1432 static int thread_cpu_timer_create(struct k_itimer
*timer
)
1434 timer
->it_clock
= THREAD_CLOCK
;
1435 return posix_cpu_timer_create(timer
);
1438 struct k_clock clock_posix_cpu
= {
1439 .clock_getres
= posix_cpu_clock_getres
,
1440 .clock_set
= posix_cpu_clock_set
,
1441 .clock_get
= posix_cpu_clock_get
,
1442 .timer_create
= posix_cpu_timer_create
,
1443 .nsleep
= posix_cpu_nsleep
,
1444 .nsleep_restart
= posix_cpu_nsleep_restart
,
1445 .timer_set
= posix_cpu_timer_set
,
1446 .timer_del
= posix_cpu_timer_del
,
1447 .timer_get
= posix_cpu_timer_get
,
1450 static __init
int init_posix_cpu_timers(void)
1452 struct k_clock process
= {
1453 .clock_getres
= process_cpu_clock_getres
,
1454 .clock_get
= process_cpu_clock_get
,
1455 .timer_create
= process_cpu_timer_create
,
1456 .nsleep
= process_cpu_nsleep
,
1457 .nsleep_restart
= process_cpu_nsleep_restart
,
1459 struct k_clock thread
= {
1460 .clock_getres
= thread_cpu_clock_getres
,
1461 .clock_get
= thread_cpu_clock_get
,
1462 .timer_create
= thread_cpu_timer_create
,
1466 posix_timers_register_clock(CLOCK_PROCESS_CPUTIME_ID
, &process
);
1467 posix_timers_register_clock(CLOCK_THREAD_CPUTIME_ID
, &thread
);
1469 cputime_to_timespec(cputime_one_jiffy
, &ts
);
1470 onecputick
= ts
.tv_nsec
;
1471 WARN_ON(ts
.tv_sec
!= 0);
1475 __initcall(init_posix_cpu_timers
);