/* * Implement CPU time clocks for the POSIX clock interface. */ #include <linux/sched.h> #include <linux/posix-timers.h> #include <linux/errno.h> #include <linux/math64.h> #include <asm/uaccess.h> #include <linux/kernel_stat.h> #include <trace/events/timer.h> /* * Called after updating RLIMIT_CPU to run cpu timer and update * tsk->signal->cputime_expires expiration cache if necessary. Needs * siglock protection since other code may update expiration cache as * well. */ void update_rlimit_cpu(struct task_struct *task, unsigned long rlim_new) { cputime_t cputime = secs_to_cputime(rlim_new); spin_lock_irq(&task->sighand->siglock); set_process_cpu_timer(task, CPUCLOCK_PROF, &cputime, NULL); spin_unlock_irq(&task->sighand->siglock); } static int check_clock(const clockid_t which_clock) { int error = 0; struct task_struct *p; const pid_t pid = CPUCLOCK_PID(which_clock); if (CPUCLOCK_WHICH(which_clock) >= CPUCLOCK_MAX) return -EINVAL; if (pid == 0) return 0; rcu_read_lock(); p = find_task_by_vpid(pid); if (!p || !(CPUCLOCK_PERTHREAD(which_clock) ? same_thread_group(p, current) : has_group_leader_pid(p))) { error = -EINVAL; } rcu_read_unlock(); return error; } static inline union cpu_time_count timespec_to_sample(const clockid_t which_clock, const struct timespec *tp) { union cpu_time_count ret; ret.sched = 0; /* high half always zero when .cpu used */ if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) { ret.sched = (unsigned long long)tp->tv_sec * NSEC_PER_SEC + tp->tv_nsec; } else { ret.cpu = timespec_to_cputime(tp); } return ret; } static void sample_to_timespec(const clockid_t which_clock, union cpu_time_count cpu, struct timespec *tp) { if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) *tp = ns_to_timespec(cpu.sched); else cputime_to_timespec(cpu.cpu, tp); } static inline int cpu_time_before(const clockid_t which_clock, union cpu_time_count now, union cpu_time_count then) { if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) { return now.sched < then.sched; } else { return cputime_lt(now.cpu, then.cpu); } } static inline void cpu_time_add(const clockid_t which_clock, union cpu_time_count *acc, union cpu_time_count val) { if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) { acc->sched += val.sched; } else { acc->cpu = cputime_add(acc->cpu, val.cpu); } } static inline union cpu_time_count cpu_time_sub(const clockid_t which_clock, union cpu_time_count a, union cpu_time_count b) { if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) { a.sched -= b.sched; } else { a.cpu = cputime_sub(a.cpu, b.cpu); } return a; } /* * Divide and limit the result to res >= 1 * * This is necessary to prevent signal delivery starvation, when the result of * the division would be rounded down to 0. */ static inline cputime_t cputime_div_non_zero(cputime_t time, unsigned long div) { cputime_t res = cputime_div(time, div); return max_t(cputime_t, res, 1); } /* * Update expiry time from increment, and increase overrun count, * given the current clock sample. */ static void bump_cpu_timer(struct k_itimer *timer, union cpu_time_count now) { int i; if (timer->it.cpu.incr.sched == 0) return; if (CPUCLOCK_WHICH(timer->it_clock) == CPUCLOCK_SCHED) { unsigned long long delta, incr; if (now.sched < timer->it.cpu.expires.sched) return; incr = timer->it.cpu.incr.sched; delta = now.sched + incr - timer->it.cpu.expires.sched; /* Don't use (incr*2 < delta), incr*2 might overflow. */ for (i = 0; incr < delta - incr; i++) incr = incr << 1; for (; i >= 0; incr >>= 1, i--) { if (delta < incr) continue; timer->it.cpu.expires.sched += incr; timer->it_overrun += 1 << i; delta -= incr; } } else { cputime_t delta, incr; if (cputime_lt(now.cpu, timer->it.cpu.expires.cpu)) return; incr = timer->it.cpu.incr.cpu; delta = cputime_sub(cputime_add(now.cpu, incr), timer->it.cpu.expires.cpu); /* Don't use (incr*2 < delta), incr*2 might overflow. */ for (i = 0; cputime_lt(incr, cputime_sub(delta, incr)); i++) incr = cputime_add(incr, incr); for (; i >= 0; incr = cputime_halve(incr), i--) { if (cputime_lt(delta, incr)) continue; timer->it.cpu.expires.cpu = cputime_add(timer->it.cpu.expires.cpu, incr); timer->it_overrun += 1 << i; delta = cputime_sub(delta, incr); } } } static inline cputime_t prof_ticks(struct task_struct *p) { return cputime_add(p->utime, p->stime); } static inline cputime_t virt_ticks(struct task_struct *p) { return p->utime; } static int posix_cpu_clock_getres(const clockid_t which_clock, struct timespec *tp) { int error = check_clock(which_clock); if (!error) { tp->tv_sec = 0; tp->tv_nsec = ((NSEC_PER_SEC + HZ - 1) / HZ); if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) { /* * If sched_clock is using a cycle counter, we * don't have any idea of its true resolution * exported, but it is much more than 1s/HZ. */ tp->tv_nsec = 1; } } return error; } static int posix_cpu_clock_set(const clockid_t which_clock, const struct timespec *tp) { /* * You can never reset a CPU clock, but we check for other errors * in the call before failing with EPERM. */ int error = check_clock(which_clock); if (error == 0) { error = -EPERM; } return error; } /* * Sample a per-thread clock for the given task. */ static int cpu_clock_sample(const clockid_t which_clock, struct task_struct *p, union cpu_time_count *cpu) { switch (CPUCLOCK_WHICH(which_clock)) { default: return -EINVAL; case CPUCLOCK_PROF: cpu->cpu = prof_ticks(p); break; case CPUCLOCK_VIRT: cpu->cpu = virt_ticks(p); break; case CPUCLOCK_SCHED: cpu->sched = task_sched_runtime(p); break; } return 0; } void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times) { struct signal_struct *sig = tsk->signal; struct task_struct *t; times->utime = sig->utime; times->stime = sig->stime; times->sum_exec_runtime = sig->sum_sched_runtime; rcu_read_lock(); /* make sure we can trust tsk->thread_group list */ if (!likely(pid_alive(tsk))) goto out; t = tsk; do { times->utime = cputime_add(times->utime, t->utime); times->stime = cputime_add(times->stime, t->stime); times->sum_exec_runtime += t->se.sum_exec_runtime; } while_each_thread(tsk, t); out: rcu_read_unlock(); } static void update_gt_cputime(struct task_cputime *a, struct task_cputime *b) { if (cputime_gt(b->utime, a->utime)) a->utime = b->utime; if (cputime_gt(b->stime, a->stime)) a->stime = b->stime; if (b->sum_exec_runtime > a->sum_exec_runtime) a->sum_exec_runtime = b->sum_exec_runtime; } void thread_group_cputimer(struct task_struct *tsk, struct task_cputime *times) { struct thread_group_cputimer *cputimer = &tsk->signal->cputimer; struct task_cputime sum; unsigned long flags; spin_lock_irqsave(&cputimer->lock, flags); if (!cputimer->running) { cputimer->running = 1; /* * The POSIX timer interface allows for absolute time expiry * values through the TIMER_ABSTIME flag, therefore we have * to synchronize the timer to the clock every time we start * it. */ thread_group_cputime(tsk, &sum); update_gt_cputime(&cputimer->cputime, &sum); } *times = cputimer->cputime; spin_unlock_irqrestore(&cputimer->lock, flags); } /* * Sample a process (thread group) clock for the given group_leader task. * Must be called with tasklist_lock held for reading. */ static int cpu_clock_sample_group(const clockid_t which_clock, struct task_struct *p, union cpu_time_count *cpu) { struct task_cputime cputime; switch (CPUCLOCK_WHICH(which_clock)) { default: return -EINVAL; case CPUCLOCK_PROF: thread_group_cputime(p, &cputime); cpu->cpu = cputime_add(cputime.utime, cputime.stime); break; case CPUCLOCK_VIRT: thread_group_cputime(p, &cputime); cpu->cpu = cputime.utime; break; case CPUCLOCK_SCHED: cpu->sched = thread_group_sched_runtime(p); break; } return 0; } static int posix_cpu_clock_get(const clockid_t which_clock, struct timespec *tp) { const pid_t pid = CPUCLOCK_PID(which_clock); int error = -EINVAL; union cpu_time_count rtn; if (pid == 0) { /* * Special case constant value for our own clocks. * We don't have to do any lookup to find ourselves. */ if (CPUCLOCK_PERTHREAD(which_clock)) { /* * Sampling just ourselves we can do with no locking. */ error = cpu_clock_sample(which_clock, current, &rtn); } else { read_lock(&tasklist_lock); error = cpu_clock_sample_group(which_clock, current, &rtn); read_unlock(&tasklist_lock); } } else { /* * Find the given PID, and validate that the caller * should be able to see it. */ struct task_struct *p; rcu_read_lock(); p = find_task_by_vpid(pid); if (p) { if (CPUCLOCK_PERTHREAD(which_clock)) { if (same_thread_group(p, current)) { error = cpu_clock_sample(which_clock, p, &rtn); } } else { read_lock(&tasklist_lock); if (thread_group_leader(p) && p->sighand) { error = cpu_clock_sample_group(which_clock, p, &rtn); } read_unlock(&tasklist_lock); } } rcu_read_unlock(); } if (error) return error; sample_to_timespec(which_clock, rtn, tp); return 0; } /* * Validate the clockid_t for a new CPU-clock timer, and initialize the timer. * This is called from sys_timer_create() and do_cpu_nanosleep() with the * new timer already all-zeros initialized. */ static int posix_cpu_timer_create(struct k_itimer *new_timer) { int ret = 0; const pid_t pid = CPUCLOCK_PID(new_timer->it_clock); struct task_struct *p; if (CPUCLOCK_WHICH(new_timer->it_clock) >= CPUCLOCK_MAX) return -EINVAL; INIT_LIST_HEAD(&new_timer->it.cpu.entry); rcu_read_lock(); if (CPUCLOCK_PERTHREAD(new_timer->it_clock)) { if (pid == 0) { p = current; } else { p = find_task_by_vpid(pid); if (p && !same_thread_group(p, current)) p = NULL; } } else { if (pid == 0) { p = current->group_leader; } else { p = find_task_by_vpid(pid); if (p && !has_group_leader_pid(p)) p = NULL; } } new_timer->it.cpu.task = p; if (p) { get_task_struct(p); } else { ret = -EINVAL; } rcu_read_unlock(); return ret; } /* * Clean up a CPU-clock timer that is about to be destroyed. * This is called from timer deletion with the timer already locked. * If we return TIMER_RETRY, it's necessary to release the timer's lock * and try again. (This happens when the timer is in the middle of firing.) */ static int posix_cpu_timer_del(struct k_itimer *timer) { struct task_struct *p = timer->it.cpu.task; int ret = 0; if (likely(p != NULL)) { read_lock(&tasklist_lock); if (unlikely(p->sighand == NULL)) { /* * We raced with the reaping of the task. * The deletion should have cleared us off the list. */ BUG_ON(!list_empty(&timer->it.cpu.entry)); } else { spin_lock(&p->sighand->siglock); if (timer->it.cpu.firing) ret = TIMER_RETRY; else list_del(&timer->it.cpu.entry); spin_unlock(&p->sighand->siglock); } read_unlock(&tasklist_lock); if (!ret) put_task_struct(p); } return ret; } /* * Clean out CPU timers still ticking when a thread exited. The task * pointer is cleared, and the expiry time is replaced with the residual * time for later timer_gettime calls to return. * This must be called with the siglock held. */ static void cleanup_timers(struct list_head *head, cputime_t utime, cputime_t stime, unsigned long long sum_exec_runtime) { struct cpu_timer_list *timer, *next; cputime_t ptime = cputime_add(utime, stime); list_for_each_entry_safe(timer, next, head, entry) { list_del_init(&timer->entry); if (cputime_lt(timer->expires.cpu, ptime)) { timer->expires.cpu = cputime_zero; } else { timer->expires.cpu = cputime_sub(timer->expires.cpu, ptime); } } ++head; list_for_each_entry_safe(timer, next, head, entry) { list_del_init(&timer->entry); if (cputime_lt(timer->expires.cpu, utime)) { timer->expires.cpu = cputime_zero; } else { timer->expires.cpu = cputime_sub(timer->expires.cpu, utime); } } ++head; list_for_each_entry_safe(timer, next, head, entry) { list_del_init(&timer->entry); if (timer->expires.sched < sum_exec_runtime) { timer->expires.sched = 0; } else { timer->expires.sched -= sum_exec_runtime; } } } /* * These are both called with the siglock held, when the current thread * is being reaped. When the final (leader) thread in the group is reaped, * posix_cpu_timers_exit_group will be called after posix_cpu_timers_exit. */ void posix_cpu_timers_exit(struct task_struct *tsk) { cleanup_timers(tsk->cpu_timers, tsk->utime, tsk->stime, tsk->se.sum_exec_runtime); } void posix_cpu_timers_exit_group(struct task_struct *tsk) { struct signal_struct *const sig = tsk->signal; cleanup_timers(tsk->signal->cpu_timers, cputime_add(tsk->utime, sig->utime), cputime_add(tsk->stime, sig->stime), tsk->se.sum_exec_runtime + sig->sum_sched_runtime); } static void clear_dead_task(struct k_itimer *timer, union cpu_time_count now) { /* * That's all for this thread or process. * We leave our residual in expires to be reported. */ put_task_struct(timer->it.cpu.task); timer->it.cpu.task = NULL; timer->it.cpu.expires = cpu_time_sub(timer->it_clock, timer->it.cpu.expires, now); } static inline int expires_gt(cputime_t expires, cputime_t new_exp) { return cputime_eq(expires, cputime_zero) || cputime_gt(expires, new_exp); } /* * Insert the timer on the appropriate list before any timers that * expire later. This must be called with the tasklist_lock held * for reading, interrupts disabled and p->sighand->siglock taken. */ static void arm_timer(struct k_itimer *timer) { struct task_struct *p = timer->it.cpu.task; struct list_head *head, *listpos; struct task_cputime *cputime_expires; struct cpu_timer_list *const nt = &timer->it.cpu; struct cpu_timer_list *next; if (CPUCLOCK_PERTHREAD(timer->it_clock)) { head = p->cpu_timers; cputime_expires = &p->cputime_expires; } else { head = p->signal->cpu_timers; cputime_expires = &p->signal->cputime_expires; } head += CPUCLOCK_WHICH(timer->it_clock); listpos = head; list_for_each_entry(next, head, entry) { if (cpu_time_before(timer->it_clock, nt->expires, next->expires)) break; listpos = &next->entry; } list_add(&nt->entry, listpos); if (listpos == head) { union cpu_time_count *exp = &nt->expires; /* * We are the new earliest-expiring POSIX 1.b timer, hence * need to update expiration cache. Take into account that * for process timers we share expiration cache with itimers * and RLIMIT_CPU and for thread timers with RLIMIT_RTTIME. */ switch (CPUCLOCK_WHICH(timer->it_clock)) { case CPUCLOCK_PROF: if (expires_gt(cputime_expires->prof_exp, exp->cpu)) cputime_expires->prof_exp = exp->cpu; break; case CPUCLOCK_VIRT: if (expires_gt(cputime_expires->virt_exp, exp->cpu)) cputime_expires->virt_exp = exp->cpu; break; case CPUCLOCK_SCHED: if (cputime_expires->sched_exp == 0 || cputime_expires->sched_exp > exp->sched) cputime_expires->sched_exp = exp->sched; break; } } } /* * The timer is locked, fire it and arrange for its reload. */ static void cpu_timer_fire(struct k_itimer *timer) { if ((timer->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE) { /* * User don't want any signal. */ timer->it.cpu.expires.sched = 0; } else if (unlikely(timer->sigq == NULL)) { /* * This a special case for clock_nanosleep, * not a normal timer from sys_timer_create. */ wake_up_process(timer->it_process); timer->it.cpu.expires.sched = 0; } else if (timer->it.cpu.incr.sched == 0) { /* * One-shot timer. Clear it as soon as it's fired. */ posix_timer_event(timer, 0); timer->it.cpu.expires.sched = 0; } else if (posix_timer_event(timer, ++timer->it_requeue_pending)) { /* * The signal did not get queued because the signal * was ignored, so we won't get any callback to * reload the timer. But we need to keep it * ticking in case the signal is deliverable next time. */ posix_cpu_timer_schedule(timer); } } /* * Sample a process (thread group) timer for the given group_leader task. * Must be called with tasklist_lock held for reading. */ static int cpu_timer_sample_group(const clockid_t which_clock, struct task_struct *p, union cpu_time_count *cpu) { struct task_cputime cputime; thread_group_cputimer(p, &cputime); switch (CPUCLOCK_WHICH(which_clock)) { default: return -EINVAL; case CPUCLOCK_PROF: cpu->cpu = cputime_add(cputime.utime, cputime.stime); break; case CPUCLOCK_VIRT: cpu->cpu = cputime.utime; break; case CPUCLOCK_SCHED: cpu->sched = cputime.sum_exec_runtime + task_delta_exec(p); break; } return 0; } /* * Guts of sys_timer_settime for CPU timers. * This is called with the timer locked and interrupts disabled. * If we return TIMER_RETRY, it's necessary to release the timer's lock * and try again. (This happens when the timer is in the middle of firing.) */ static int posix_cpu_timer_set(struct k_itimer *timer, int flags, struct itimerspec *new, struct itimerspec *old) { struct task_struct *p = timer->it.cpu.task; union cpu_time_count old_expires, new_expires, old_incr, val; int ret; if (unlikely(p == NULL)) { /* * Timer refers to a dead task's clock. */ return -ESRCH; } new_expires = timespec_to_sample(timer->it_clock, &new->it_value); read_lock(&tasklist_lock); /* * We need the tasklist_lock to protect against reaping that * clears p->sighand. If p has just been reaped, we can no * longer get any information about it at all. */ if (unlikely(p->sighand == NULL)) { read_unlock(&tasklist_lock); put_task_struct(p); timer->it.cpu.task = NULL; return -ESRCH; } /* * Disarm any old timer after extracting its expiry time. */ BUG_ON(!irqs_disabled()); ret = 0; old_incr = timer->it.cpu.incr; spin_lock(&p->sighand->siglock); old_expires = timer->it.cpu.expires; if (unlikely(timer->it.cpu.firing)) { timer->it.cpu.firing = -1; ret = TIMER_RETRY; } else list_del_init(&timer->it.cpu.entry); /* * We need to sample the current value to convert the new * value from to relative and absolute, and to convert the * old value from absolute to relative. To set a process * timer, we need a sample to balance the thread expiry * times (in arm_timer). With an absolute time, we must * check if it's already passed. In short, we need a sample. */ if (CPUCLOCK_PERTHREAD(timer->it_clock)) { cpu_clock_sample(timer->it_clock, p, &val); } else { cpu_timer_sample_group(timer->it_clock, p, &val); } if (old) { if (old_expires.sched == 0) { old->it_value.tv_sec = 0; old->it_value.tv_nsec = 0; } else { /* * Update the timer in case it has * overrun already. If it has, * we'll report it as having overrun * and with the next reloaded timer * already ticking, though we are * swallowing that pending * notification here to install the * new setting. */ bump_cpu_timer(timer, val); if (cpu_time_before(timer->it_clock, val, timer->it.cpu.expires)) { old_expires = cpu_time_sub( timer->it_clock, timer->it.cpu.expires, val); sample_to_timespec(timer->it_clock, old_expires, &old->it_value); } else { old->it_value.tv_nsec = 1; old->it_value.tv_sec = 0; } } } if (unlikely(ret)) { /* * We are colliding with the timer actually firing. * Punt after filling in the timer's old value, and * disable this firing since we are already reporting * it as an overrun (thanks to bump_cpu_timer above). */ spin_unlock(&p->sighand->siglock); read_unlock(&tasklist_lock); goto out; } if (new_expires.sched != 0 && !(flags & TIMER_ABSTIME)) { cpu_time_add(timer->it_clock, &new_expires, val); } /* * Install the new expiry time (or zero). * For a timer with no notification action, we don't actually * arm the timer (we'll just fake it for timer_gettime). */ timer->it.cpu.expires = new_expires; if (new_expires.sched != 0 && cpu_time_before(timer->it_clock, val, new_expires)) { arm_timer(timer); } spin_unlock(&p->sighand->siglock); read_unlock(&tasklist_lock); /* * Install the new reload setting, and * set up the signal and overrun bookkeeping. */ timer->it.cpu.incr = timespec_to_sample(timer->it_clock, &new->it_interval); /* * This acts as a modification timestamp for the timer, * so any automatic reload attempt will punt on seeing * that we have reset the timer manually. */ timer->it_requeue_pending = (timer->it_requeue_pending + 2) & ~REQUEUE_PENDING; timer->it_overrun_last = 0; timer->it_overrun = -1; if (new_expires.sched != 0 && !cpu_time_before(timer->it_clock, val, new_expires)) { /* * The designated time already passed, so we notify * immediately, even if the thread never runs to * accumulate more time on this clock. */ cpu_timer_fire(timer); } ret = 0; out: if (old) { sample_to_timespec(timer->it_clock, old_incr, &old->it_interval); } return ret; } static void posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec *itp) { union cpu_time_count now; struct task_struct *p = timer->it.cpu.task; int clear_dead; /* * Easy part: convert the reload time. */ sample_to_timespec(timer->it_clock, timer->it.cpu.incr, &itp->it_interval); if (timer->it.cpu.expires.sched == 0) { /* Timer not armed at all. */ itp->it_value.tv_sec = itp->it_value.tv_nsec = 0; return; } if (unlikely(p == NULL)) { /* * This task already died and the timer will never fire. * In this case, expires is actually the dead value. */ dead: sample_to_timespec(timer->it_clock, timer->it.cpu.expires, &itp->it_value); return; } /* * Sample the clock to take the difference with the expiry time. */ if (CPUCLOCK_PERTHREAD(timer->it_clock)) { cpu_clock_sample(timer->it_clock, p, &now); clear_dead = p->exit_state; } else { read_lock(&tasklist_lock); if (unlikely(p->sighand == NULL)) { /* * The process has been reaped. * We can't even collect a sample any more. * Call the timer disarmed, nothing else to do. */ put_task_struct(p); timer->it.cpu.task = NULL; timer->it.cpu.expires.sched = 0; read_unlock(&tasklist_lock); goto dead; } else { cpu_timer_sample_group(timer->it_clock, p, &now); clear_dead = (unlikely(p->exit_state) && thread_group_empty(p)); } read_unlock(&tasklist_lock); } if (unlikely(clear_dead)) { /* * We've noticed that the thread is dead, but * not yet reaped. Take this opportunity to * drop our task ref. */ clear_dead_task(timer, now); goto dead; } if (cpu_time_before(timer->it_clock, now, timer->it.cpu.expires)) { sample_to_timespec(timer->it_clock, cpu_time_sub(timer->it_clock, timer->it.cpu.expires, now), &itp->it_value); } else { /* * The timer should have expired already, but the firing * hasn't taken place yet. Say it's just about to expire. */ itp->it_value.tv_nsec = 1; itp->it_value.tv_sec = 0; } } /* * Check for any per-thread CPU timers that have fired and move them off * the tsk->cpu_timers[N] list onto the firing list. Here we update the * tsk->it_*_expires values to reflect the remaining thread CPU timers. */ static void check_thread_timers(struct task_struct *tsk, struct list_head *firing) { int maxfire; struct list_head *timers = tsk->cpu_timers; struct signal_struct *const sig = tsk->signal; unsigned long soft; maxfire = 20; tsk->cputime_expires.prof_exp = cputime_zero; while (!list_empty(timers)) { struct cpu_timer_list *t = list_first_entry(timers, struct cpu_timer_list, entry); if (!--maxfire || cputime_lt(prof_ticks(tsk), t->expires.cpu)) { tsk->cputime_expires.prof_exp = t->expires.cpu; break; } t->firing = 1; list_move_tail(&t->entry, firing); } ++timers; maxfire = 20; tsk->cputime_expires.virt_exp = cputime_zero; while (!list_empty(timers)) { struct cpu_timer_list *t = list_first_entry(timers, struct cpu_timer_list, entry); if (!--maxfire || cputime_lt(virt_ticks(tsk), t->expires.cpu)) { tsk->cputime_expires.virt_exp = t->expires.cpu; break; } t->firing = 1; list_move_tail(&t->entry, firing); } ++timers; maxfire = 20; tsk->cputime_expires.sched_exp = 0; while (!list_empty(timers)) { struct cpu_timer_list *t = list_first_entry(timers, struct cpu_timer_list, entry); if (!--maxfire || tsk->se.sum_exec_runtime < t->expires.sched) { tsk->cputime_expires.sched_exp = t->expires.sched; break; } t->firing = 1; list_move_tail(&t->entry, firing); } /* * Check for the special case thread timers. */ soft = ACCESS_ONCE(sig->rlim[RLIMIT_RTTIME].rlim_cur); if (soft != RLIM_INFINITY) { unsigned long hard = ACCESS_ONCE(sig->rlim[RLIMIT_RTTIME].rlim_max); if (hard != RLIM_INFINITY && tsk->rt.timeout > DIV_ROUND_UP(hard, USEC_PER_SEC/HZ)) { /* * At the hard limit, we just die. * No need to calculate anything else now. */ __group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk); return; } if (tsk->rt.timeout > DIV_ROUND_UP(soft, USEC_PER_SEC/HZ)) { /* * At the soft limit, send a SIGXCPU every second. */ if (soft < hard) { soft += USEC_PER_SEC; sig->rlim[RLIMIT_RTTIME].rlim_cur = soft; } printk(KERN_INFO "RT Watchdog Timeout: %s[%d]\n", tsk->comm, task_pid_nr(tsk)); __group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk); } } } static void stop_process_timers(struct signal_struct *sig) { struct thread_group_cputimer *cputimer = &sig->cputimer; unsigned long flags; spin_lock_irqsave(&cputimer->lock, flags); cputimer->running = 0; spin_unlock_irqrestore(&cputimer->lock, flags); } static u32 onecputick; static void check_cpu_itimer(struct task_struct *tsk, struct cpu_itimer *it, cputime_t *expires, cputime_t cur_time, int signo) { if (cputime_eq(it->expires, cputime_zero)) return; if (cputime_ge(cur_time, it->expires)) { if (!cputime_eq(it->incr, cputime_zero)) { it->expires = cputime_add(it->expires, it->incr); it->error += it->incr_error; if (it->error >= onecputick) { it->expires = cputime_sub(it->expires, cputime_one_jiffy); it->error -= onecputick; } } else { it->expires = cputime_zero; } trace_itimer_expire(signo == SIGPROF ? ITIMER_PROF : ITIMER_VIRTUAL, tsk->signal->leader_pid, cur_time); __group_send_sig_info(signo, SEND_SIG_PRIV, tsk); } if (!cputime_eq(it->expires, cputime_zero) && (cputime_eq(*expires, cputime_zero) || cputime_lt(it->expires, *expires))) { *expires = it->expires; } } /** * task_cputime_zero - Check a task_cputime struct for all zero fields. * * @cputime: The struct to compare. * * Checks @cputime to see if all fields are zero. Returns true if all fields * are zero, false if any field is nonzero. */ static inline int task_cputime_zero(const struct task_cputime *cputime) { if (cputime_eq(cputime->utime, cputime_zero) && cputime_eq(cputime->stime, cputime_zero) && cputime->sum_exec_runtime == 0) return 1; return 0; } /* * Check for any per-thread CPU timers that have fired and move them * off the tsk->*_timers list onto the firing list. Per-thread timers * have already been taken off. */ static void check_process_timers(struct task_struct *tsk, struct list_head *firing) { int maxfire; struct signal_struct *const sig = tsk->signal; cputime_t utime, ptime, virt_expires, prof_expires; unsigned long long sum_sched_runtime, sched_expires; struct list_head *timers = sig->cpu_timers; struct task_cputime cputime; unsigned long soft; /* * Collect the current process totals. */ thread_group_cputimer(tsk, &cputime); utime = cputime.utime; ptime = cputime_add(utime, cputime.stime); sum_sched_runtime = cputime.sum_exec_runtime; maxfire = 20; prof_expires = cputime_zero; while (!list_empty(timers)) { struct cpu_timer_list *tl = list_first_entry(timers, struct cpu_timer_list, entry); if (!--maxfire || cputime_lt(ptime, tl->expires.cpu)) { prof_expires = tl->expires.cpu; break; } tl->firing = 1; list_move_tail(&tl->entry, firing); } ++timers; maxfire = 20; virt_expires = cputime_zero; while (!list_empty(timers)) { struct cpu_timer_list *tl = list_first_entry(timers, struct cpu_timer_list, entry); if (!--maxfire || cputime_lt(utime, tl->expires.cpu)) { virt_expires = tl->expires.cpu; break; } tl->firing = 1; list_move_tail(&tl->entry, firing); } ++timers; maxfire = 20; sched_expires = 0; while (!list_empty(timers)) { struct cpu_timer_list *tl = list_first_entry(timers, struct cpu_timer_list, entry); if (!--maxfire || sum_sched_runtime < tl->expires.sched) { sched_expires = tl->expires.sched; break; } tl->firing = 1; list_move_tail(&tl->entry, firing); } /* * Check for the special case process timers. */ check_cpu_itimer(tsk, &sig->it[CPUCLOCK_PROF], &prof_expires, ptime, SIGPROF); check_cpu_itimer(tsk, &sig->it[CPUCLOCK_VIRT], &virt_expires, utime, SIGVTALRM); soft = ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur); if (soft != RLIM_INFINITY) { unsigned long psecs = cputime_to_secs(ptime); unsigned long hard = ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_max); cputime_t x; if (psecs >= hard) { /* * At the hard limit, we just die. * No need to calculate anything else now. */ __group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk); return; } if (psecs >= soft) { /* * At the soft limit, send a SIGXCPU every second. */ __group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk); if (soft < hard) { soft++; sig->rlim[RLIMIT_CPU].rlim_cur = soft; } } x = secs_to_cputime(soft); if (cputime_eq(prof_expires, cputime_zero) || cputime_lt(x, prof_expires)) { prof_expires = x; } } sig->cputime_expires.prof_exp = prof_expires; sig->cputime_expires.virt_exp = virt_expires; sig->cputime_expires.sched_exp = sched_expires; if (task_cputime_zero(&sig->cputime_expires)) stop_process_timers(sig); } /* * This is called from the signal code (via do_schedule_next_timer) * when the last timer signal was delivered and we have to reload the timer. */ void posix_cpu_timer_schedule(struct k_itimer *timer) { struct task_struct *p = timer->it.cpu.task; union cpu_time_count now; if (unlikely(p == NULL)) /* * The task was cleaned up already, no future firings. */ goto out; /* * Fetch the current sample and update the timer's expiry time. */ if (CPUCLOCK_PERTHREAD(timer->it_clock)) { cpu_clock_sample(timer->it_clock, p, &now); bump_cpu_timer(timer, now); if (unlikely(p->exit_state)) { clear_dead_task(timer, now); goto out; } read_lock(&tasklist_lock); /* arm_timer needs it. */ spin_lock(&p->sighand->siglock); } else { read_lock(&tasklist_lock); if (unlikely(p->sighand == NULL)) { /* * The process has been reaped. * We can't even collect a sample any more. */ put_task_struct(p); timer->it.cpu.task = p = NULL; timer->it.cpu.expires.sched = 0; goto out_unlock; } else if (unlikely(p->exit_state) && thread_group_empty(p)) { /* * We've noticed that the thread is dead, but * not yet reaped. Take this opportunity to * drop our task ref. */ clear_dead_task(timer, now); goto out_unlock; } spin_lock(&p->sighand->siglock); cpu_timer_sample_group(timer->it_clock, p, &now); bump_cpu_timer(timer, now); /* Leave the tasklist_lock locked for the call below. */ } /* * Now re-arm for the new expiry time. */ BUG_ON(!irqs_disabled()); arm_timer(timer); spin_unlock(&p->sighand->siglock); out_unlock: read_unlock(&tasklist_lock); out: timer->it_overrun_last = timer->it_overrun; timer->it_overrun = -1; ++timer->it_requeue_pending; } /** * task_cputime_expired - Compare two task_cputime entities. * * @sample: The task_cputime structure to be checked for expiration. * @expires: Expiration times, against which @sample will be checked. * * Checks @sample against @expires to see if any field of @sample has expired. * Returns true if any field of the former is greater than the corresponding * field of the latter if the latter field is set. Otherwise returns false. */ static inline int task_cputime_expired(const struct task_cputime *sample, const struct task_cputime *expires) { if (!cputime_eq(expires->utime, cputime_zero) && cputime_ge(sample->utime, expires->utime)) return 1; if (!cputime_eq(expires->stime, cputime_zero) && cputime_ge(cputime_add(sample->utime, sample->stime), expires->stime)) return 1; if (expires->sum_exec_runtime != 0 && sample->sum_exec_runtime >= expires->sum_exec_runtime) return 1; return 0; } /** * fastpath_timer_check - POSIX CPU timers fast path. * * @tsk: The task (thread) being checked. * * Check the task and thread group timers. If both are zero (there are no * timers set) return false. Otherwise snapshot the task and thread group * timers and compare them with the corresponding expiration times. Return * true if a timer has expired, else return false. */ static inline int fastpath_timer_check(struct task_struct *tsk) { struct signal_struct *sig; if (!task_cputime_zero(&tsk->cputime_expires)) { struct task_cputime task_sample = { .utime = tsk->utime, .stime = tsk->stime, .sum_exec_runtime = tsk->se.sum_exec_runtime }; if (task_cputime_expired(&task_sample, &tsk->cputime_expires)) return 1; } sig = tsk->signal; if (sig->cputimer.running) { struct task_cputime group_sample; spin_lock(&sig->cputimer.lock); group_sample = sig->cputimer.cputime; spin_unlock(&sig->cputimer.lock); if (task_cputime_expired(&group_sample, &sig->cputime_expires)) return 1; } return 0; } /* * This is called from the timer interrupt handler. The irq handler has * already updated our counts. We need to check if any timers fire now. * Interrupts are disabled. */ void run_posix_cpu_timers(struct task_struct *tsk) { LIST_HEAD(firing); struct k_itimer *timer, *next; unsigned long flags; BUG_ON(!irqs_disabled()); /* * The fast path checks that there are no expired thread or thread * group timers. If that's so, just return. */ if (!fastpath_timer_check(tsk)) return; if (!lock_task_sighand(tsk, &flags)) return; /* * Here we take off tsk->signal->cpu_timers[N] and * tsk->cpu_timers[N] all the timers that are firing, and * put them on the firing list. */ check_thread_timers(tsk, &firing); /* * If there are any active process wide timers (POSIX 1.b, itimers, * RLIMIT_CPU) cputimer must be running. */ if (tsk->signal->cputimer.running) check_process_timers(tsk, &firing); /* * We must release these locks before taking any timer's lock. * There is a potential race with timer deletion here, as the * siglock now protects our private firing list. We have set * the firing flag in each timer, so that a deletion attempt * that gets the timer lock before we do will give it up and * spin until we've taken care of that timer below. */ unlock_task_sighand(tsk, &flags); /* * Now that all the timers on our list have the firing flag, * no one will touch their list entries but us. We'll take * each timer's lock before clearing its firing flag, so no * timer call will interfere. */ list_for_each_entry_safe(timer, next, &firing, it.cpu.entry) { int cpu_firing; spin_lock(&timer->it_lock); list_del_init(&timer->it.cpu.entry); cpu_firing = timer->it.cpu.firing; timer->it.cpu.firing = 0; /* * The firing flag is -1 if we collided with a reset * of the timer, which already reported this * almost-firing as an overrun. So don't generate an event. */ if (likely(cpu_firing >= 0)) cpu_timer_fire(timer); spin_unlock(&timer->it_lock); } } /* * Set one of the process-wide special case CPU timers or RLIMIT_CPU. * The tsk->sighand->siglock must be held by the caller. */ void set_process_cpu_timer(struct task_struct *tsk, unsigned int clock_idx, cputime_t *newval, cputime_t *oldval) { union cpu_time_count now; BUG_ON(clock_idx == CPUCLOCK_SCHED); cpu_timer_sample_group(clock_idx, tsk, &now); if (oldval) { /* * We are setting itimer. The *oldval is absolute and we update * it to be relative, *newval argument is relative and we update * it to be absolute. */ if (!cputime_eq(*oldval, cputime_zero)) { if (cputime_le(*oldval, now.cpu)) { /* Just about to fire. */ *oldval = cputime_one_jiffy; } else { *oldval = cputime_sub(*oldval, now.cpu); } } if (cputime_eq(*newval, cputime_zero)) return; *newval = cputime_add(*newval, now.cpu); } /* * Update expiration cache if we are the earliest timer, or eventually * RLIMIT_CPU limit is earlier than prof_exp cpu timer expire. */ switch (clock_idx) { case CPUCLOCK_PROF: if (expires_gt(tsk->signal->cputime_expires.prof_exp, *newval)) tsk->signal->cputime_expires.prof_exp = *newval; break; case CPUCLOCK_VIRT: if (expires_gt(tsk->signal->cputime_expires.virt_exp, *newval)) tsk->signal->cputime_expires.virt_exp = *newval; break; } } static int do_cpu_nanosleep(const clockid_t which_clock, int flags, struct timespec *rqtp, struct itimerspec *it) { struct k_itimer timer; int error; /* * Set up a temporary timer and then wait for it to go off. */ memset(&timer, 0, sizeof timer); spin_lock_init(&timer.it_lock); timer.it_clock = which_clock; timer.it_overrun = -1; error = posix_cpu_timer_create(&timer); timer.it_process = current; if (!error) { static struct itimerspec zero_it; memset(it, 0, sizeof *it); it->it_value = *rqtp; spin_lock_irq(&timer.it_lock); error = posix_cpu_timer_set(&timer, flags, it, NULL); if (error) { spin_unlock_irq(&timer.it_lock); return error; } while (!signal_pending(current)) { if (timer.it.cpu.expires.sched == 0) { /* * Our timer fired and was reset. */ spin_unlock_irq(&timer.it_lock); return 0; } /* * Block until cpu_timer_fire (or a signal) wakes us. */ __set_current_state(TASK_INTERRUPTIBLE); spin_unlock_irq(&timer.it_lock); schedule(); spin_lock_irq(&timer.it_lock); } /* * We were interrupted by a signal. */ sample_to_timespec(which_clock, timer.it.cpu.expires, rqtp); posix_cpu_timer_set(&timer, 0, &zero_it, it); spin_unlock_irq(&timer.it_lock); if ((it->it_value.tv_sec | it->it_value.tv_nsec) == 0) { /* * It actually did fire already. */ return 0; } error = -ERESTART_RESTARTBLOCK; } return error; } static long posix_cpu_nsleep_restart(struct restart_block *restart_block); static int posix_cpu_nsleep(const clockid_t which_clock, int flags, struct timespec *rqtp, struct timespec __user *rmtp) { struct restart_block *restart_block = ¤t_thread_info()->restart_block; struct itimerspec it; int error; /* * Diagnose required errors first. */ if (CPUCLOCK_PERTHREAD(which_clock) && (CPUCLOCK_PID(which_clock) == 0 || CPUCLOCK_PID(which_clock) == current->pid)) return -EINVAL; error = do_cpu_nanosleep(which_clock, flags, rqtp, &it); if (error == -ERESTART_RESTARTBLOCK) { if (flags & TIMER_ABSTIME) return -ERESTARTNOHAND; /* * Report back to the user the time still remaining. */ if (rmtp && copy_to_user(rmtp, &it.it_value, sizeof *rmtp)) return -EFAULT; restart_block->fn = posix_cpu_nsleep_restart; restart_block->nanosleep.clockid = which_clock; restart_block->nanosleep.rmtp = rmtp; restart_block->nanosleep.expires = timespec_to_ns(rqtp); } return error; } static long posix_cpu_nsleep_restart(struct restart_block *restart_block) { clockid_t which_clock = restart_block->nanosleep.clockid; struct timespec t; struct itimerspec it; int error; t = ns_to_timespec(restart_block->nanosleep.expires); error = do_cpu_nanosleep(which_clock, TIMER_ABSTIME, &t, &it); if (error == -ERESTART_RESTARTBLOCK) { struct timespec __user *rmtp = restart_block->nanosleep.rmtp; /* * Report back to the user the time still remaining. */ if (rmtp && copy_to_user(rmtp, &it.it_value, sizeof *rmtp)) return -EFAULT; restart_block->nanosleep.expires = timespec_to_ns(&t); } return error; } #define PROCESS_CLOCK MAKE_PROCESS_CPUCLOCK(0, CPUCLOCK_SCHED) #define THREAD_CLOCK MAKE_THREAD_CPUCLOCK(0, CPUCLOCK_SCHED) static int process_cpu_clock_getres(const clockid_t which_clock, struct timespec *tp) { return posix_cpu_clock_getres(PROCESS_CLOCK, tp); } static int process_cpu_clock_get(const clockid_t which_clock, struct timespec *tp) { return posix_cpu_clock_get(PROCESS_CLOCK, tp); } static int process_cpu_timer_create(struct k_itimer *timer) { timer->it_clock = PROCESS_CLOCK; return posix_cpu_timer_create(timer); } static int process_cpu_nsleep(const clockid_t which_clock, int flags, struct timespec *rqtp, struct timespec __user *rmtp) { return posix_cpu_nsleep(PROCESS_CLOCK, flags, rqtp, rmtp); } static long process_cpu_nsleep_restart(struct restart_block *restart_block) { return -EINVAL; } static int thread_cpu_clock_getres(const clockid_t which_clock, struct timespec *tp) { return posix_cpu_clock_getres(THREAD_CLOCK, tp); } static int thread_cpu_clock_get(const clockid_t which_clock, struct timespec *tp) { return posix_cpu_clock_get(THREAD_CLOCK, tp); } static int thread_cpu_timer_create(struct k_itimer *timer) { timer->it_clock = THREAD_CLOCK; return posix_cpu_timer_create(timer); } struct k_clock clock_posix_cpu = { .clock_getres = posix_cpu_clock_getres, .clock_set = posix_cpu_clock_set, .clock_get = posix_cpu_clock_get, .timer_create = posix_cpu_timer_create, .nsleep = posix_cpu_nsleep, .nsleep_restart = posix_cpu_nsleep_restart, .timer_set = posix_cpu_timer_set, .timer_del = posix_cpu_timer_del, .timer_get = posix_cpu_timer_get, }; static __init int init_posix_cpu_timers(void) { struct k_clock process = { .clock_getres = process_cpu_clock_getres, .clock_get = process_cpu_clock_get, .timer_create = process_cpu_timer_create, .nsleep = process_cpu_nsleep, .nsleep_restart = process_cpu_nsleep_restart, }; struct k_clock thread = { .clock_getres = thread_cpu_clock_getres, .clock_get = thread_cpu_clock_get, .timer_create = thread_cpu_timer_create, }; struct timespec ts; posix_timers_register_clock(CLOCK_PROCESS_CPUTIME_ID, &process); posix_timers_register_clock(CLOCK_THREAD_CPUTIME_ID, &thread); cputime_to_timespec(cputime_one_jiffy, &ts); onecputick = ts.tv_nsec; WARN_ON(ts.tv_sec != 0); return 0; } __initcall(init_posix_cpu_timers);