2 * Implement CPU time clocks for the POSIX clock interface.
5 #include <linux/sched/signal.h>
6 #include <linux/sched/cputime.h>
7 #include <linux/posix-timers.h>
8 #include <linux/errno.h>
9 #include <linux/math64.h>
10 #include <linux/uaccess.h>
11 #include <linux/kernel_stat.h>
12 #include <trace/events/timer.h>
13 #include <linux/tick.h>
14 #include <linux/workqueue.h>
15 #include <linux/compat.h>
17 #include "posix-timers.h"
19 static void posix_cpu_timer_rearm(struct k_itimer *timer);
22 * Called after updating RLIMIT_CPU to run cpu timer and update
23 * tsk->signal->cputime_expires expiration cache if necessary. Needs
24 * siglock protection since other code may update expiration cache as
27 void update_rlimit_cpu(struct task_struct *task, unsigned long rlim_new)
29 u64 nsecs = rlim_new * NSEC_PER_SEC;
31 spin_lock_irq(&task->sighand->siglock);
32 set_process_cpu_timer(task, CPUCLOCK_PROF, &nsecs, NULL);
33 spin_unlock_irq(&task->sighand->siglock);
36 static int check_clock(const clockid_t which_clock)
39 struct task_struct *p;
40 const pid_t pid = CPUCLOCK_PID(which_clock);
42 if (CPUCLOCK_WHICH(which_clock) >= CPUCLOCK_MAX)
49 p = find_task_by_vpid(pid);
50 if (!p || !(CPUCLOCK_PERTHREAD(which_clock) ?
51 same_thread_group(p, current) : has_group_leader_pid(p))) {
60 * Update expiry time from increment, and increase overrun count,
61 * given the current clock sample.
63 static void bump_cpu_timer(struct k_itimer *timer, u64 now)
68 if (timer->it.cpu.incr == 0)
71 if (now < timer->it.cpu.expires)
74 incr = timer->it.cpu.incr;
75 delta = now + incr - timer->it.cpu.expires;
77 /* Don't use (incr*2 < delta), incr*2 might overflow. */
78 for (i = 0; incr < delta - incr; i++)
81 for (; i >= 0; incr >>= 1, i--) {
85 timer->it.cpu.expires += incr;
86 timer->it_overrun += 1 << i;
92 * task_cputime_zero - Check a task_cputime struct for all zero fields.
94 * @cputime: The struct to compare.
96 * Checks @cputime to see if all fields are zero. Returns true if all fields
97 * are zero, false if any field is nonzero.
99 static inline int task_cputime_zero(const struct task_cputime *cputime)
101 if (!cputime->utime && !cputime->stime && !cputime->sum_exec_runtime)
106 static inline u64 prof_ticks(struct task_struct *p)
110 task_cputime(p, &utime, &stime);
112 return utime + stime;
114 static inline u64 virt_ticks(struct task_struct *p)
118 task_cputime(p, &utime, &stime);
124 posix_cpu_clock_getres(const clockid_t which_clock, struct timespec64 *tp)
126 int error = check_clock(which_clock);
129 tp->tv_nsec = ((NSEC_PER_SEC + HZ - 1) / HZ);
130 if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
132 * If sched_clock is using a cycle counter, we
133 * don't have any idea of its true resolution
134 * exported, but it is much more than 1s/HZ.
143 posix_cpu_clock_set(const clockid_t which_clock, const struct timespec64 *tp)
146 * You can never reset a CPU clock, but we check for other errors
147 * in the call before failing with EPERM.
149 int error = check_clock(which_clock);
158 * Sample a per-thread clock for the given task.
160 static int cpu_clock_sample(const clockid_t which_clock,
161 struct task_struct *p, u64 *sample)
163 switch (CPUCLOCK_WHICH(which_clock)) {
167 *sample = prof_ticks(p);
170 *sample = virt_ticks(p);
173 *sample = task_sched_runtime(p);
180 * Set cputime to sum_cputime if sum_cputime > cputime. Use cmpxchg
181 * to avoid race conditions with concurrent updates to cputime.
183 static inline void __update_gt_cputime(atomic64_t *cputime, u64 sum_cputime)
187 curr_cputime = atomic64_read(cputime);
188 if (sum_cputime > curr_cputime) {
189 if (atomic64_cmpxchg(cputime, curr_cputime, sum_cputime) != curr_cputime)
194 static void update_gt_cputime(struct task_cputime_atomic *cputime_atomic, struct task_cputime *sum)
196 __update_gt_cputime(&cputime_atomic->utime, sum->utime);
197 __update_gt_cputime(&cputime_atomic->stime, sum->stime);
198 __update_gt_cputime(&cputime_atomic->sum_exec_runtime, sum->sum_exec_runtime);
201 /* Sample task_cputime_atomic values in "atomic_timers", store results in "times". */
202 static inline void sample_cputime_atomic(struct task_cputime *times,
203 struct task_cputime_atomic *atomic_times)
205 times->utime = atomic64_read(&atomic_times->utime);
206 times->stime = atomic64_read(&atomic_times->stime);
207 times->sum_exec_runtime = atomic64_read(&atomic_times->sum_exec_runtime);
210 void thread_group_cputimer(struct task_struct *tsk, struct task_cputime *times)
212 struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
213 struct task_cputime sum;
215 /* Check if cputimer isn't running. This is accessed without locking. */
216 if (!READ_ONCE(cputimer->running)) {
218 * The POSIX timer interface allows for absolute time expiry
219 * values through the TIMER_ABSTIME flag, therefore we have
220 * to synchronize the timer to the clock every time we start it.
222 thread_group_cputime(tsk, &sum);
223 update_gt_cputime(&cputimer->cputime_atomic, &sum);
226 * We're setting cputimer->running without a lock. Ensure
227 * this only gets written to in one operation. We set
228 * running after update_gt_cputime() as a small optimization,
229 * but barriers are not required because update_gt_cputime()
230 * can handle concurrent updates.
232 WRITE_ONCE(cputimer->running, true);
234 sample_cputime_atomic(times, &cputimer->cputime_atomic);
238 * Sample a process (thread group) clock for the given group_leader task.
239 * Must be called with task sighand lock held for safe while_each_thread()
242 static int cpu_clock_sample_group(const clockid_t which_clock,
243 struct task_struct *p,
246 struct task_cputime cputime;
248 switch (CPUCLOCK_WHICH(which_clock)) {
252 thread_group_cputime(p, &cputime);
253 *sample = cputime.utime + cputime.stime;
256 thread_group_cputime(p, &cputime);
257 *sample = cputime.utime;
260 thread_group_cputime(p, &cputime);
261 *sample = cputime.sum_exec_runtime;
267 static int posix_cpu_clock_get_task(struct task_struct *tsk,
268 const clockid_t which_clock,
269 struct timespec64 *tp)
274 if (CPUCLOCK_PERTHREAD(which_clock)) {
275 if (same_thread_group(tsk, current))
276 err = cpu_clock_sample(which_clock, tsk, &rtn);
278 if (tsk == current || thread_group_leader(tsk))
279 err = cpu_clock_sample_group(which_clock, tsk, &rtn);
283 *tp = ns_to_timespec64(rtn);
289 static int posix_cpu_clock_get(const clockid_t which_clock, struct timespec64 *tp)
291 const pid_t pid = CPUCLOCK_PID(which_clock);
296 * Special case constant value for our own clocks.
297 * We don't have to do any lookup to find ourselves.
299 err = posix_cpu_clock_get_task(current, which_clock, tp);
302 * Find the given PID, and validate that the caller
303 * should be able to see it.
305 struct task_struct *p;
307 p = find_task_by_vpid(pid);
309 err = posix_cpu_clock_get_task(p, which_clock, tp);
317 * Validate the clockid_t for a new CPU-clock timer, and initialize the timer.
318 * This is called from sys_timer_create() and do_cpu_nanosleep() with the
319 * new timer already all-zeros initialized.
321 static int posix_cpu_timer_create(struct k_itimer *new_timer)
324 const pid_t pid = CPUCLOCK_PID(new_timer->it_clock);
325 struct task_struct *p;
327 if (CPUCLOCK_WHICH(new_timer->it_clock) >= CPUCLOCK_MAX)
330 new_timer->kclock = &clock_posix_cpu;
332 INIT_LIST_HEAD(&new_timer->it.cpu.entry);
335 if (CPUCLOCK_PERTHREAD(new_timer->it_clock)) {
339 p = find_task_by_vpid(pid);
340 if (p && !same_thread_group(p, current))
345 p = current->group_leader;
347 p = find_task_by_vpid(pid);
348 if (p && !has_group_leader_pid(p))
352 new_timer->it.cpu.task = p;
364 * Clean up a CPU-clock timer that is about to be destroyed.
365 * This is called from timer deletion with the timer already locked.
366 * If we return TIMER_RETRY, it's necessary to release the timer's lock
367 * and try again. (This happens when the timer is in the middle of firing.)
369 static int posix_cpu_timer_del(struct k_itimer *timer)
373 struct sighand_struct *sighand;
374 struct task_struct *p = timer->it.cpu.task;
376 WARN_ON_ONCE(p == NULL);
379 * Protect against sighand release/switch in exit/exec and process/
380 * thread timer list entry concurrent read/writes.
382 sighand = lock_task_sighand(p, &flags);
383 if (unlikely(sighand == NULL)) {
385 * We raced with the reaping of the task.
386 * The deletion should have cleared us off the list.
388 WARN_ON_ONCE(!list_empty(&timer->it.cpu.entry));
390 if (timer->it.cpu.firing)
393 list_del(&timer->it.cpu.entry);
395 unlock_task_sighand(p, &flags);
404 static void cleanup_timers_list(struct list_head *head)
406 struct cpu_timer_list *timer, *next;
408 list_for_each_entry_safe(timer, next, head, entry)
409 list_del_init(&timer->entry);
413 * Clean out CPU timers still ticking when a thread exited. The task
414 * pointer is cleared, and the expiry time is replaced with the residual
415 * time for later timer_gettime calls to return.
416 * This must be called with the siglock held.
418 static void cleanup_timers(struct list_head *head)
420 cleanup_timers_list(head);
421 cleanup_timers_list(++head);
422 cleanup_timers_list(++head);
426 * These are both called with the siglock held, when the current thread
427 * is being reaped. When the final (leader) thread in the group is reaped,
428 * posix_cpu_timers_exit_group will be called after posix_cpu_timers_exit.
430 void posix_cpu_timers_exit(struct task_struct *tsk)
432 cleanup_timers(tsk->cpu_timers);
434 void posix_cpu_timers_exit_group(struct task_struct *tsk)
436 cleanup_timers(tsk->signal->cpu_timers);
439 static inline int expires_gt(u64 expires, u64 new_exp)
441 return expires == 0 || expires > new_exp;
445 * Insert the timer on the appropriate list before any timers that
446 * expire later. This must be called with the sighand lock held.
448 static void arm_timer(struct k_itimer *timer)
450 struct task_struct *p = timer->it.cpu.task;
451 struct list_head *head, *listpos;
452 struct task_cputime *cputime_expires;
453 struct cpu_timer_list *const nt = &timer->it.cpu;
454 struct cpu_timer_list *next;
456 if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
457 head = p->cpu_timers;
458 cputime_expires = &p->cputime_expires;
460 head = p->signal->cpu_timers;
461 cputime_expires = &p->signal->cputime_expires;
463 head += CPUCLOCK_WHICH(timer->it_clock);
466 list_for_each_entry(next, head, entry) {
467 if (nt->expires < next->expires)
469 listpos = &next->entry;
471 list_add(&nt->entry, listpos);
473 if (listpos == head) {
474 u64 exp = nt->expires;
477 * We are the new earliest-expiring POSIX 1.b timer, hence
478 * need to update expiration cache. Take into account that
479 * for process timers we share expiration cache with itimers
480 * and RLIMIT_CPU and for thread timers with RLIMIT_RTTIME.
483 switch (CPUCLOCK_WHICH(timer->it_clock)) {
485 if (expires_gt(cputime_expires->prof_exp, exp))
486 cputime_expires->prof_exp = exp;
489 if (expires_gt(cputime_expires->virt_exp, exp))
490 cputime_expires->virt_exp = exp;
493 if (expires_gt(cputime_expires->sched_exp, exp))
494 cputime_expires->sched_exp = exp;
497 if (CPUCLOCK_PERTHREAD(timer->it_clock))
498 tick_dep_set_task(p, TICK_DEP_BIT_POSIX_TIMER);
500 tick_dep_set_signal(p->signal, TICK_DEP_BIT_POSIX_TIMER);
505 * The timer is locked, fire it and arrange for its reload.
507 static void cpu_timer_fire(struct k_itimer *timer)
509 if ((timer->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE) {
511 * User don't want any signal.
513 timer->it.cpu.expires = 0;
514 } else if (unlikely(timer->sigq == NULL)) {
516 * This a special case for clock_nanosleep,
517 * not a normal timer from sys_timer_create.
519 wake_up_process(timer->it_process);
520 timer->it.cpu.expires = 0;
521 } else if (timer->it.cpu.incr == 0) {
523 * One-shot timer. Clear it as soon as it's fired.
525 posix_timer_event(timer, 0);
526 timer->it.cpu.expires = 0;
527 } else if (posix_timer_event(timer, ++timer->it_requeue_pending)) {
529 * The signal did not get queued because the signal
530 * was ignored, so we won't get any callback to
531 * reload the timer. But we need to keep it
532 * ticking in case the signal is deliverable next time.
534 posix_cpu_timer_rearm(timer);
535 ++timer->it_requeue_pending;
540 * Sample a process (thread group) timer for the given group_leader task.
541 * Must be called with task sighand lock held for safe while_each_thread()
544 static int cpu_timer_sample_group(const clockid_t which_clock,
545 struct task_struct *p, u64 *sample)
547 struct task_cputime cputime;
549 thread_group_cputimer(p, &cputime);
550 switch (CPUCLOCK_WHICH(which_clock)) {
554 *sample = cputime.utime + cputime.stime;
557 *sample = cputime.utime;
560 *sample = cputime.sum_exec_runtime;
567 * Guts of sys_timer_settime for CPU timers.
568 * This is called with the timer locked and interrupts disabled.
569 * If we return TIMER_RETRY, it's necessary to release the timer's lock
570 * and try again. (This happens when the timer is in the middle of firing.)
572 static int posix_cpu_timer_set(struct k_itimer *timer, int timer_flags,
573 struct itimerspec64 *new, struct itimerspec64 *old)
576 struct sighand_struct *sighand;
577 struct task_struct *p = timer->it.cpu.task;
578 u64 old_expires, new_expires, old_incr, val;
581 WARN_ON_ONCE(p == NULL);
584 * Use the to_ktime conversion because that clamps the maximum
585 * value to KTIME_MAX and avoid multiplication overflows.
587 new_expires = ktime_to_ns(timespec64_to_ktime(new->it_value));
590 * Protect against sighand release/switch in exit/exec and p->cpu_timers
591 * and p->signal->cpu_timers read/write in arm_timer()
593 sighand = lock_task_sighand(p, &flags);
595 * If p has just been reaped, we can no
596 * longer get any information about it at all.
598 if (unlikely(sighand == NULL)) {
603 * Disarm any old timer after extracting its expiry time.
605 WARN_ON_ONCE(!irqs_disabled());
608 old_incr = timer->it.cpu.incr;
609 old_expires = timer->it.cpu.expires;
610 if (unlikely(timer->it.cpu.firing)) {
611 timer->it.cpu.firing = -1;
614 list_del_init(&timer->it.cpu.entry);
617 * We need to sample the current value to convert the new
618 * value from to relative and absolute, and to convert the
619 * old value from absolute to relative. To set a process
620 * timer, we need a sample to balance the thread expiry
621 * times (in arm_timer). With an absolute time, we must
622 * check if it's already passed. In short, we need a sample.
624 if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
625 cpu_clock_sample(timer->it_clock, p, &val);
627 cpu_timer_sample_group(timer->it_clock, p, &val);
631 if (old_expires == 0) {
632 old->it_value.tv_sec = 0;
633 old->it_value.tv_nsec = 0;
636 * Update the timer in case it has
637 * overrun already. If it has,
638 * we'll report it as having overrun
639 * and with the next reloaded timer
640 * already ticking, though we are
641 * swallowing that pending
642 * notification here to install the
645 bump_cpu_timer(timer, val);
646 if (val < timer->it.cpu.expires) {
647 old_expires = timer->it.cpu.expires - val;
648 old->it_value = ns_to_timespec64(old_expires);
650 old->it_value.tv_nsec = 1;
651 old->it_value.tv_sec = 0;
658 * We are colliding with the timer actually firing.
659 * Punt after filling in the timer's old value, and
660 * disable this firing since we are already reporting
661 * it as an overrun (thanks to bump_cpu_timer above).
663 unlock_task_sighand(p, &flags);
667 if (new_expires != 0 && !(timer_flags & TIMER_ABSTIME)) {
672 * Install the new expiry time (or zero).
673 * For a timer with no notification action, we don't actually
674 * arm the timer (we'll just fake it for timer_gettime).
676 timer->it.cpu.expires = new_expires;
677 if (new_expires != 0 && val < new_expires) {
681 unlock_task_sighand(p, &flags);
683 * Install the new reload setting, and
684 * set up the signal and overrun bookkeeping.
686 timer->it.cpu.incr = timespec64_to_ns(&new->it_interval);
689 * This acts as a modification timestamp for the timer,
690 * so any automatic reload attempt will punt on seeing
691 * that we have reset the timer manually.
693 timer->it_requeue_pending = (timer->it_requeue_pending + 2) &
695 timer->it_overrun_last = 0;
696 timer->it_overrun = -1;
698 if (new_expires != 0 && !(val < new_expires)) {
700 * The designated time already passed, so we notify
701 * immediately, even if the thread never runs to
702 * accumulate more time on this clock.
704 cpu_timer_fire(timer);
710 old->it_interval = ns_to_timespec64(old_incr);
715 static void posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec64 *itp)
718 struct task_struct *p = timer->it.cpu.task;
720 WARN_ON_ONCE(p == NULL);
723 * Easy part: convert the reload time.
725 itp->it_interval = ns_to_timespec64(timer->it.cpu.incr);
727 if (!timer->it.cpu.expires)
731 * Sample the clock to take the difference with the expiry time.
733 if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
734 cpu_clock_sample(timer->it_clock, p, &now);
736 struct sighand_struct *sighand;
740 * Protect against sighand release/switch in exit/exec and
741 * also make timer sampling safe if it ends up calling
742 * thread_group_cputime().
744 sighand = lock_task_sighand(p, &flags);
745 if (unlikely(sighand == NULL)) {
747 * The process has been reaped.
748 * We can't even collect a sample any more.
749 * Call the timer disarmed, nothing else to do.
751 timer->it.cpu.expires = 0;
754 cpu_timer_sample_group(timer->it_clock, p, &now);
755 unlock_task_sighand(p, &flags);
759 if (now < timer->it.cpu.expires) {
760 itp->it_value = ns_to_timespec64(timer->it.cpu.expires - now);
763 * The timer should have expired already, but the firing
764 * hasn't taken place yet. Say it's just about to expire.
766 itp->it_value.tv_nsec = 1;
767 itp->it_value.tv_sec = 0;
771 static unsigned long long
772 check_timers_list(struct list_head *timers,
773 struct list_head *firing,
774 unsigned long long curr)
778 while (!list_empty(timers)) {
779 struct cpu_timer_list *t;
781 t = list_first_entry(timers, struct cpu_timer_list, entry);
783 if (!--maxfire || curr < t->expires)
787 list_move_tail(&t->entry, firing);
794 * Check for any per-thread CPU timers that have fired and move them off
795 * the tsk->cpu_timers[N] list onto the firing list. Here we update the
796 * tsk->it_*_expires values to reflect the remaining thread CPU timers.
798 static void check_thread_timers(struct task_struct *tsk,
799 struct list_head *firing)
801 struct list_head *timers = tsk->cpu_timers;
802 struct task_cputime *tsk_expires = &tsk->cputime_expires;
807 * If cputime_expires is zero, then there are no active
808 * per thread CPU timers.
810 if (task_cputime_zero(&tsk->cputime_expires))
813 expires = check_timers_list(timers, firing, prof_ticks(tsk));
814 tsk_expires->prof_exp = expires;
816 expires = check_timers_list(++timers, firing, virt_ticks(tsk));
817 tsk_expires->virt_exp = expires;
819 tsk_expires->sched_exp = check_timers_list(++timers, firing,
820 tsk->se.sum_exec_runtime);
823 * Check for the special case thread timers.
825 soft = task_rlimit(tsk, RLIMIT_RTTIME);
826 if (soft != RLIM_INFINITY) {
827 unsigned long hard = task_rlimit_max(tsk, RLIMIT_RTTIME);
829 if (hard != RLIM_INFINITY &&
830 tsk->rt.timeout > DIV_ROUND_UP(hard, USEC_PER_SEC/HZ)) {
832 * At the hard limit, we just die.
833 * No need to calculate anything else now.
835 if (print_fatal_signals) {
836 pr_info("CPU Watchdog Timeout (hard): %s[%d]\n",
837 tsk->comm, task_pid_nr(tsk));
839 __group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk);
842 if (tsk->rt.timeout > DIV_ROUND_UP(soft, USEC_PER_SEC/HZ)) {
844 * At the soft limit, send a SIGXCPU every second.
847 soft += USEC_PER_SEC;
848 tsk->signal->rlim[RLIMIT_RTTIME].rlim_cur =
851 if (print_fatal_signals) {
852 pr_info("RT Watchdog Timeout (soft): %s[%d]\n",
853 tsk->comm, task_pid_nr(tsk));
855 __group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk);
858 if (task_cputime_zero(tsk_expires))
859 tick_dep_clear_task(tsk, TICK_DEP_BIT_POSIX_TIMER);
862 static inline void stop_process_timers(struct signal_struct *sig)
864 struct thread_group_cputimer *cputimer = &sig->cputimer;
866 /* Turn off cputimer->running. This is done without locking. */
867 WRITE_ONCE(cputimer->running, false);
868 tick_dep_clear_signal(sig, TICK_DEP_BIT_POSIX_TIMER);
871 static void check_cpu_itimer(struct task_struct *tsk, struct cpu_itimer *it,
872 u64 *expires, u64 cur_time, int signo)
877 if (cur_time >= it->expires) {
879 it->expires += it->incr;
883 trace_itimer_expire(signo == SIGPROF ?
884 ITIMER_PROF : ITIMER_VIRTUAL,
885 tsk->signal->leader_pid, cur_time);
886 __group_send_sig_info(signo, SEND_SIG_PRIV, tsk);
889 if (it->expires && (!*expires || it->expires < *expires))
890 *expires = it->expires;
894 * Check for any per-thread CPU timers that have fired and move them
895 * off the tsk->*_timers list onto the firing list. Per-thread timers
896 * have already been taken off.
898 static void check_process_timers(struct task_struct *tsk,
899 struct list_head *firing)
901 struct signal_struct *const sig = tsk->signal;
902 u64 utime, ptime, virt_expires, prof_expires;
903 u64 sum_sched_runtime, sched_expires;
904 struct list_head *timers = sig->cpu_timers;
905 struct task_cputime cputime;
909 * If cputimer is not running, then there are no active
910 * process wide timers (POSIX 1.b, itimers, RLIMIT_CPU).
912 if (!READ_ONCE(tsk->signal->cputimer.running))
916 * Signify that a thread is checking for process timers.
917 * Write access to this field is protected by the sighand lock.
919 sig->cputimer.checking_timer = true;
922 * Collect the current process totals.
924 thread_group_cputimer(tsk, &cputime);
925 utime = cputime.utime;
926 ptime = utime + cputime.stime;
927 sum_sched_runtime = cputime.sum_exec_runtime;
929 prof_expires = check_timers_list(timers, firing, ptime);
930 virt_expires = check_timers_list(++timers, firing, utime);
931 sched_expires = check_timers_list(++timers, firing, sum_sched_runtime);
934 * Check for the special case process timers.
936 check_cpu_itimer(tsk, &sig->it[CPUCLOCK_PROF], &prof_expires, ptime,
938 check_cpu_itimer(tsk, &sig->it[CPUCLOCK_VIRT], &virt_expires, utime,
940 soft = task_rlimit(tsk, RLIMIT_CPU);
941 if (soft != RLIM_INFINITY) {
942 unsigned long psecs = div_u64(ptime, NSEC_PER_SEC);
943 unsigned long hard = task_rlimit_max(tsk, RLIMIT_CPU);
947 * At the hard limit, we just die.
948 * No need to calculate anything else now.
950 if (print_fatal_signals) {
951 pr_info("RT Watchdog Timeout (hard): %s[%d]\n",
952 tsk->comm, task_pid_nr(tsk));
954 __group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk);
959 * At the soft limit, send a SIGXCPU every second.
961 if (print_fatal_signals) {
962 pr_info("CPU Watchdog Timeout (soft): %s[%d]\n",
963 tsk->comm, task_pid_nr(tsk));
965 __group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk);
968 sig->rlim[RLIMIT_CPU].rlim_cur = soft;
971 x = soft * NSEC_PER_SEC;
972 if (!prof_expires || x < prof_expires)
976 sig->cputime_expires.prof_exp = prof_expires;
977 sig->cputime_expires.virt_exp = virt_expires;
978 sig->cputime_expires.sched_exp = sched_expires;
979 if (task_cputime_zero(&sig->cputime_expires))
980 stop_process_timers(sig);
982 sig->cputimer.checking_timer = false;
986 * This is called from the signal code (via posixtimer_rearm)
987 * when the last timer signal was delivered and we have to reload the timer.
989 static void posix_cpu_timer_rearm(struct k_itimer *timer)
991 struct sighand_struct *sighand;
993 struct task_struct *p = timer->it.cpu.task;
996 WARN_ON_ONCE(p == NULL);
999 * Fetch the current sample and update the timer's expiry time.
1001 if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
1002 cpu_clock_sample(timer->it_clock, p, &now);
1003 bump_cpu_timer(timer, now);
1004 if (unlikely(p->exit_state))
1007 /* Protect timer list r/w in arm_timer() */
1008 sighand = lock_task_sighand(p, &flags);
1013 * Protect arm_timer() and timer sampling in case of call to
1014 * thread_group_cputime().
1016 sighand = lock_task_sighand(p, &flags);
1017 if (unlikely(sighand == NULL)) {
1019 * The process has been reaped.
1020 * We can't even collect a sample any more.
1022 timer->it.cpu.expires = 0;
1024 } else if (unlikely(p->exit_state) && thread_group_empty(p)) {
1025 /* If the process is dying, no need to rearm */
1028 cpu_timer_sample_group(timer->it_clock, p, &now);
1029 bump_cpu_timer(timer, now);
1030 /* Leave the sighand locked for the call below. */
1034 * Now re-arm for the new expiry time.
1036 WARN_ON_ONCE(!irqs_disabled());
1039 unlock_task_sighand(p, &flags);
1043 * task_cputime_expired - Compare two task_cputime entities.
1045 * @sample: The task_cputime structure to be checked for expiration.
1046 * @expires: Expiration times, against which @sample will be checked.
1048 * Checks @sample against @expires to see if any field of @sample has expired.
1049 * Returns true if any field of the former is greater than the corresponding
1050 * field of the latter if the latter field is set. Otherwise returns false.
1052 static inline int task_cputime_expired(const struct task_cputime *sample,
1053 const struct task_cputime *expires)
1055 if (expires->utime && sample->utime >= expires->utime)
1057 if (expires->stime && sample->utime + sample->stime >= expires->stime)
1059 if (expires->sum_exec_runtime != 0 &&
1060 sample->sum_exec_runtime >= expires->sum_exec_runtime)
1066 * fastpath_timer_check - POSIX CPU timers fast path.
1068 * @tsk: The task (thread) being checked.
1070 * Check the task and thread group timers. If both are zero (there are no
1071 * timers set) return false. Otherwise snapshot the task and thread group
1072 * timers and compare them with the corresponding expiration times. Return
1073 * true if a timer has expired, else return false.
1075 static inline int fastpath_timer_check(struct task_struct *tsk)
1077 struct signal_struct *sig;
1079 if (!task_cputime_zero(&tsk->cputime_expires)) {
1080 struct task_cputime task_sample;
1082 task_cputime(tsk, &task_sample.utime, &task_sample.stime);
1083 task_sample.sum_exec_runtime = tsk->se.sum_exec_runtime;
1084 if (task_cputime_expired(&task_sample, &tsk->cputime_expires))
1090 * Check if thread group timers expired when the cputimer is
1091 * running and no other thread in the group is already checking
1092 * for thread group cputimers. These fields are read without the
1093 * sighand lock. However, this is fine because this is meant to
1094 * be a fastpath heuristic to determine whether we should try to
1095 * acquire the sighand lock to check/handle timers.
1097 * In the worst case scenario, if 'running' or 'checking_timer' gets
1098 * set but the current thread doesn't see the change yet, we'll wait
1099 * until the next thread in the group gets a scheduler interrupt to
1100 * handle the timer. This isn't an issue in practice because these
1101 * types of delays with signals actually getting sent are expected.
1103 if (READ_ONCE(sig->cputimer.running) &&
1104 !READ_ONCE(sig->cputimer.checking_timer)) {
1105 struct task_cputime group_sample;
1107 sample_cputime_atomic(&group_sample, &sig->cputimer.cputime_atomic);
1109 if (task_cputime_expired(&group_sample, &sig->cputime_expires))
1117 * This is called from the timer interrupt handler. The irq handler has
1118 * already updated our counts. We need to check if any timers fire now.
1119 * Interrupts are disabled.
1121 void run_posix_cpu_timers(struct task_struct *tsk)
1124 struct k_itimer *timer, *next;
1125 unsigned long flags;
1127 WARN_ON_ONCE(!irqs_disabled());
1130 * The fast path checks that there are no expired thread or thread
1131 * group timers. If that's so, just return.
1133 if (!fastpath_timer_check(tsk))
1136 if (!lock_task_sighand(tsk, &flags))
1139 * Here we take off tsk->signal->cpu_timers[N] and
1140 * tsk->cpu_timers[N] all the timers that are firing, and
1141 * put them on the firing list.
1143 check_thread_timers(tsk, &firing);
1145 check_process_timers(tsk, &firing);
1148 * We must release these locks before taking any timer's lock.
1149 * There is a potential race with timer deletion here, as the
1150 * siglock now protects our private firing list. We have set
1151 * the firing flag in each timer, so that a deletion attempt
1152 * that gets the timer lock before we do will give it up and
1153 * spin until we've taken care of that timer below.
1155 unlock_task_sighand(tsk, &flags);
1158 * Now that all the timers on our list have the firing flag,
1159 * no one will touch their list entries but us. We'll take
1160 * each timer's lock before clearing its firing flag, so no
1161 * timer call will interfere.
1163 list_for_each_entry_safe(timer, next, &firing, it.cpu.entry) {
1166 spin_lock(&timer->it_lock);
1167 list_del_init(&timer->it.cpu.entry);
1168 cpu_firing = timer->it.cpu.firing;
1169 timer->it.cpu.firing = 0;
1171 * The firing flag is -1 if we collided with a reset
1172 * of the timer, which already reported this
1173 * almost-firing as an overrun. So don't generate an event.
1175 if (likely(cpu_firing >= 0))
1176 cpu_timer_fire(timer);
1177 spin_unlock(&timer->it_lock);
1182 * Set one of the process-wide special case CPU timers or RLIMIT_CPU.
1183 * The tsk->sighand->siglock must be held by the caller.
1185 void set_process_cpu_timer(struct task_struct *tsk, unsigned int clock_idx,
1186 u64 *newval, u64 *oldval)
1190 WARN_ON_ONCE(clock_idx == CPUCLOCK_SCHED);
1191 cpu_timer_sample_group(clock_idx, tsk, &now);
1195 * We are setting itimer. The *oldval is absolute and we update
1196 * it to be relative, *newval argument is relative and we update
1197 * it to be absolute.
1200 if (*oldval <= now) {
1201 /* Just about to fire. */
1202 *oldval = TICK_NSEC;
1214 * Update expiration cache if we are the earliest timer, or eventually
1215 * RLIMIT_CPU limit is earlier than prof_exp cpu timer expire.
1217 switch (clock_idx) {
1219 if (expires_gt(tsk->signal->cputime_expires.prof_exp, *newval))
1220 tsk->signal->cputime_expires.prof_exp = *newval;
1223 if (expires_gt(tsk->signal->cputime_expires.virt_exp, *newval))
1224 tsk->signal->cputime_expires.virt_exp = *newval;
1228 tick_dep_set_signal(tsk->signal, TICK_DEP_BIT_POSIX_TIMER);
1231 static int do_cpu_nanosleep(const clockid_t which_clock, int flags,
1232 const struct timespec64 *rqtp)
1234 struct itimerspec64 it;
1235 struct k_itimer timer;
1240 * Set up a temporary timer and then wait for it to go off.
1242 memset(&timer, 0, sizeof timer);
1243 spin_lock_init(&timer.it_lock);
1244 timer.it_clock = which_clock;
1245 timer.it_overrun = -1;
1246 error = posix_cpu_timer_create(&timer);
1247 timer.it_process = current;
1249 static struct itimerspec64 zero_it;
1250 struct restart_block *restart;
1252 memset(&it, 0, sizeof(it));
1253 it.it_value = *rqtp;
1255 spin_lock_irq(&timer.it_lock);
1256 error = posix_cpu_timer_set(&timer, flags, &it, NULL);
1258 spin_unlock_irq(&timer.it_lock);
1262 while (!signal_pending(current)) {
1263 if (timer.it.cpu.expires == 0) {
1265 * Our timer fired and was reset, below
1266 * deletion can not fail.
1268 posix_cpu_timer_del(&timer);
1269 spin_unlock_irq(&timer.it_lock);
1274 * Block until cpu_timer_fire (or a signal) wakes us.
1276 __set_current_state(TASK_INTERRUPTIBLE);
1277 spin_unlock_irq(&timer.it_lock);
1279 spin_lock_irq(&timer.it_lock);
1283 * We were interrupted by a signal.
1285 expires = timer.it.cpu.expires;
1286 error = posix_cpu_timer_set(&timer, 0, &zero_it, &it);
1289 * Timer is now unarmed, deletion can not fail.
1291 posix_cpu_timer_del(&timer);
1293 spin_unlock_irq(&timer.it_lock);
1295 while (error == TIMER_RETRY) {
1297 * We need to handle case when timer was or is in the
1298 * middle of firing. In other cases we already freed
1301 spin_lock_irq(&timer.it_lock);
1302 error = posix_cpu_timer_del(&timer);
1303 spin_unlock_irq(&timer.it_lock);
1306 if ((it.it_value.tv_sec | it.it_value.tv_nsec) == 0) {
1308 * It actually did fire already.
1313 error = -ERESTART_RESTARTBLOCK;
1315 * Report back to the user the time still remaining.
1317 restart = ¤t->restart_block;
1318 restart->nanosleep.expires = expires;
1319 if (restart->nanosleep.type != TT_NONE)
1320 error = nanosleep_copyout(restart, &it.it_value);
1326 static long posix_cpu_nsleep_restart(struct restart_block *restart_block);
1328 static int posix_cpu_nsleep(const clockid_t which_clock, int flags,
1329 const struct timespec64 *rqtp)
1331 struct restart_block *restart_block = ¤t->restart_block;
1335 * Diagnose required errors first.
1337 if (CPUCLOCK_PERTHREAD(which_clock) &&
1338 (CPUCLOCK_PID(which_clock) == 0 ||
1339 CPUCLOCK_PID(which_clock) == task_pid_vnr(current)))
1342 error = do_cpu_nanosleep(which_clock, flags, rqtp);
1344 if (error == -ERESTART_RESTARTBLOCK) {
1346 if (flags & TIMER_ABSTIME)
1347 return -ERESTARTNOHAND;
1349 restart_block->fn = posix_cpu_nsleep_restart;
1350 restart_block->nanosleep.clockid = which_clock;
1355 static long posix_cpu_nsleep_restart(struct restart_block *restart_block)
1357 clockid_t which_clock = restart_block->nanosleep.clockid;
1358 struct timespec64 t;
1360 t = ns_to_timespec64(restart_block->nanosleep.expires);
1362 return do_cpu_nanosleep(which_clock, TIMER_ABSTIME, &t);
1365 #define PROCESS_CLOCK MAKE_PROCESS_CPUCLOCK(0, CPUCLOCK_SCHED)
1366 #define THREAD_CLOCK MAKE_THREAD_CPUCLOCK(0, CPUCLOCK_SCHED)
1368 static int process_cpu_clock_getres(const clockid_t which_clock,
1369 struct timespec64 *tp)
1371 return posix_cpu_clock_getres(PROCESS_CLOCK, tp);
1373 static int process_cpu_clock_get(const clockid_t which_clock,
1374 struct timespec64 *tp)
1376 return posix_cpu_clock_get(PROCESS_CLOCK, tp);
1378 static int process_cpu_timer_create(struct k_itimer *timer)
1380 timer->it_clock = PROCESS_CLOCK;
1381 return posix_cpu_timer_create(timer);
1383 static int process_cpu_nsleep(const clockid_t which_clock, int flags,
1384 const struct timespec64 *rqtp)
1386 return posix_cpu_nsleep(PROCESS_CLOCK, flags, rqtp);
1388 static int thread_cpu_clock_getres(const clockid_t which_clock,
1389 struct timespec64 *tp)
1391 return posix_cpu_clock_getres(THREAD_CLOCK, tp);
1393 static int thread_cpu_clock_get(const clockid_t which_clock,
1394 struct timespec64 *tp)
1396 return posix_cpu_clock_get(THREAD_CLOCK, tp);
1398 static int thread_cpu_timer_create(struct k_itimer *timer)
1400 timer->it_clock = THREAD_CLOCK;
1401 return posix_cpu_timer_create(timer);
1404 const struct k_clock clock_posix_cpu = {
1405 .clock_getres = posix_cpu_clock_getres,
1406 .clock_set = posix_cpu_clock_set,
1407 .clock_get = posix_cpu_clock_get,
1408 .timer_create = posix_cpu_timer_create,
1409 .nsleep = posix_cpu_nsleep,
1410 .timer_set = posix_cpu_timer_set,
1411 .timer_del = posix_cpu_timer_del,
1412 .timer_get = posix_cpu_timer_get,
1413 .timer_rearm = posix_cpu_timer_rearm,
1416 const struct k_clock clock_process = {
1417 .clock_getres = process_cpu_clock_getres,
1418 .clock_get = process_cpu_clock_get,
1419 .timer_create = process_cpu_timer_create,
1420 .nsleep = process_cpu_nsleep,
1423 const struct k_clock clock_thread = {
1424 .clock_getres = thread_cpu_clock_getres,
1425 .clock_get = thread_cpu_clock_get,
1426 .timer_create = thread_cpu_timer_create,