/* * Implement CPU time clocks for the POSIX clock interface. */ #include <linux/sched.h> #include <linux/posix-timers.h> #include <asm/uaccess.h> #include <linux/errno.h> 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; read_lock(&tasklist_lock); p = find_task_by_pid(pid); if (!p || !(CPUCLOCK_PERTHREAD(which_clock) ? same_thread_group(p, current) : thread_group_leader(p))) { error = -EINVAL; } read_unlock(&tasklist_lock); 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->tv_sec = div_long_long_rem(cpu.sched, NSEC_PER_SEC, &tp->tv_nsec); } 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 inline unsigned long long sched_ns(struct task_struct *p) { return task_sched_runtime(p); } 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; } 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 = sched_ns(p); break; } return 0; } /* * Sample a process (thread group) clock for the given group_leader task. * Must be called with tasklist_lock held for reading. * Must be called with tasklist_lock held for reading, and p->sighand->siglock. */ static int cpu_clock_sample_group_locked(unsigned int clock_idx, struct task_struct *p, union cpu_time_count *cpu) { struct task_struct *t = p; switch (clock_idx) { default: return -EINVAL; case CPUCLOCK_PROF: cpu->cpu = cputime_add(p->signal->utime, p->signal->stime); do { cpu->cpu = cputime_add(cpu->cpu, prof_ticks(t)); t = next_thread(t); } while (t != p); break; case CPUCLOCK_VIRT: cpu->cpu = p->signal->utime; do { cpu->cpu = cputime_add(cpu->cpu, virt_ticks(t)); t = next_thread(t); } while (t != p); break; case CPUCLOCK_SCHED: cpu->sched = p->signal->sum_sched_runtime; /* Add in each other live thread. */ while ((t = next_thread(t)) != p) { cpu->sched += t->se.sum_exec_runtime; } cpu->sched += sched_ns(p); break; } return 0; } /* * 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) { int ret; unsigned long flags; spin_lock_irqsave(&p->sighand->siglock, flags); ret = cpu_clock_sample_group_locked(CPUCLOCK_WHICH(which_clock), p, cpu); spin_unlock_irqrestore(&p->sighand->siglock, flags); return ret; } 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_pid(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->signal) { 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 with the new timer already locked. */ 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); new_timer->it.cpu.incr.sched = 0; new_timer->it.cpu.expires.sched = 0; read_lock(&tasklist_lock); if (CPUCLOCK_PERTHREAD(new_timer->it_clock)) { if (pid == 0) { p = current; } else { p = find_task_by_pid(pid); if (p && !same_thread_group(p, current)) p = NULL; } } else { if (pid == 0) { p = current->group_leader; } else { p = find_task_by_pid(pid); if (p && !thread_group_leader(p)) p = NULL; } } new_timer->it.cpu.task = p; if (p) { get_task_struct(p); } else { ret = -EINVAL; } read_unlock(&tasklist_lock); 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.) */ 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->signal == 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) { cleanup_timers(tsk->signal->cpu_timers, cputime_add(tsk->utime, tsk->signal->utime), cputime_add(tsk->stime, tsk->signal->stime), tsk->se.sum_exec_runtime + tsk->signal->sum_sched_runtime); } /* * Set the expiry times of all the threads in the process so one of them * will go off before the process cumulative expiry total is reached. */ static void process_timer_rebalance(struct task_struct *p, unsigned int clock_idx, union cpu_time_count expires, union cpu_time_count val) { cputime_t ticks, left; unsigned long long ns, nsleft; struct task_struct *t = p; unsigned int nthreads = atomic_read(&p->signal->live); if (!nthreads) return; switch (clock_idx) { default: BUG(); break; case CPUCLOCK_PROF: left = cputime_div_non_zero(cputime_sub(expires.cpu, val.cpu), nthreads); do { if (likely(!(t->flags & PF_EXITING))) { ticks = cputime_add(prof_ticks(t), left); if (cputime_eq(t->it_prof_expires, cputime_zero) || cputime_gt(t->it_prof_expires, ticks)) { t->it_prof_expires = ticks; } } t = next_thread(t); } while (t != p); break; case CPUCLOCK_VIRT: left = cputime_div_non_zero(cputime_sub(expires.cpu, val.cpu), nthreads); do { if (likely(!(t->flags & PF_EXITING))) { ticks = cputime_add(virt_ticks(t), left); if (cputime_eq(t->it_virt_expires, cputime_zero) || cputime_gt(t->it_virt_expires, ticks)) { t->it_virt_expires = ticks; } } t = next_thread(t); } while (t != p); break; case CPUCLOCK_SCHED: nsleft = expires.sched - val.sched; do_div(nsleft, nthreads); nsleft = max_t(unsigned long long, nsleft, 1); do { if (likely(!(t->flags & PF_EXITING))) { ns = t->se.sum_exec_runtime + nsleft; if (t->it_sched_expires == 0 || t->it_sched_expires > ns) { t->it_sched_expires = ns; } } t = next_thread(t); } while (t != p); break; } } 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); } /* * Insert the timer on the appropriate list before any timers that * expire later. This must be called with the tasklist_lock held * for reading, and interrupts disabled. */ static void arm_timer(struct k_itimer *timer, union cpu_time_count now) { struct task_struct *p = timer->it.cpu.task; struct list_head *head, *listpos; struct cpu_timer_list *const nt = &timer->it.cpu; struct cpu_timer_list *next; unsigned long i; head = (CPUCLOCK_PERTHREAD(timer->it_clock) ? p->cpu_timers : p->signal->cpu_timers); head += CPUCLOCK_WHICH(timer->it_clock); BUG_ON(!irqs_disabled()); spin_lock(&p->sighand->siglock); listpos = head; if (CPUCLOCK_WHICH(timer->it_clock) == CPUCLOCK_SCHED) { list_for_each_entry(next, head, entry) { if (next->expires.sched > nt->expires.sched) break; listpos = &next->entry; } } else { list_for_each_entry(next, head, entry) { if (cputime_gt(next->expires.cpu, nt->expires.cpu)) break; listpos = &next->entry; } } list_add(&nt->entry, listpos); if (listpos == head) { /* * We are the new earliest-expiring timer. * If we are a thread timer, there can always * be a process timer telling us to stop earlier. */ if (CPUCLOCK_PERTHREAD(timer->it_clock)) { switch (CPUCLOCK_WHICH(timer->it_clock)) { default: BUG(); case CPUCLOCK_PROF: if (cputime_eq(p->it_prof_expires, cputime_zero) || cputime_gt(p->it_prof_expires, nt->expires.cpu)) p->it_prof_expires = nt->expires.cpu; break; case CPUCLOCK_VIRT: if (cputime_eq(p->it_virt_expires, cputime_zero) || cputime_gt(p->it_virt_expires, nt->expires.cpu)) p->it_virt_expires = nt->expires.cpu; break; case CPUCLOCK_SCHED: if (p->it_sched_expires == 0 || p->it_sched_expires > nt->expires.sched) p->it_sched_expires = nt->expires.sched; break; } } else { /* * For a process timer, we must balance * all the live threads' expirations. */ switch (CPUCLOCK_WHICH(timer->it_clock)) { default: BUG(); case CPUCLOCK_VIRT: if (!cputime_eq(p->signal->it_virt_expires, cputime_zero) && cputime_lt(p->signal->it_virt_expires, timer->it.cpu.expires.cpu)) break; goto rebalance; case CPUCLOCK_PROF: if (!cputime_eq(p->signal->it_prof_expires, cputime_zero) && cputime_lt(p->signal->it_prof_expires, timer->it.cpu.expires.cpu)) break; i = p->signal->rlim[RLIMIT_CPU].rlim_cur; if (i != RLIM_INFINITY && i <= cputime_to_secs(timer->it.cpu.expires.cpu)) break; goto rebalance; case CPUCLOCK_SCHED: rebalance: process_timer_rebalance( timer->it.cpu.task, CPUCLOCK_WHICH(timer->it_clock), timer->it.cpu.expires, now); break; } } } spin_unlock(&p->sighand->siglock); } /* * The timer is locked, fire it and arrange for its reload. */ static void cpu_timer_fire(struct k_itimer *timer) { 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); } } /* * 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.) */ 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, 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->signal. If p has just been reaped, we can no * longer get any information about it at all. */ if (unlikely(p->signal == 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; 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); spin_unlock(&p->sighand->siglock); /* * 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_clock_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). */ 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 && (timer->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE && cpu_time_before(timer->it_clock, val, new_expires)) { arm_timer(timer, val); } 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 && (timer->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE && !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, timer->it.cpu.incr, &old->it_interval); } return ret; } 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->signal == 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_clock_sample_group(timer->it_clock, p, &now); clear_dead = (unlikely(p->exit_state) && thread_group_empty(p)); } read_unlock(&tasklist_lock); } if ((timer->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE) { if (timer->it.cpu.incr.sched == 0 && cpu_time_before(timer->it_clock, timer->it.cpu.expires, now)) { /* * Do-nothing timer expired and has no reload, * so it's as if it was never set. */ timer->it.cpu.expires.sched = 0; itp->it_value.tv_sec = itp->it_value.tv_nsec = 0; return; } /* * Account for any expirations and reloads that should * have happened. */ bump_cpu_timer(timer, now); } 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; maxfire = 20; tsk->it_prof_expires = 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->it_prof_expires = t->expires.cpu; break; } t->firing = 1; list_move_tail(&t->entry, firing); } ++timers; maxfire = 20; tsk->it_virt_expires = 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->it_virt_expires = t->expires.cpu; break; } t->firing = 1; list_move_tail(&t->entry, firing); } ++timers; maxfire = 20; tsk->it_sched_expires = 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->it_sched_expires = t->expires.sched; break; } t->firing = 1; list_move_tail(&t->entry, firing); } } /* * 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, stime, ptime, virt_expires, prof_expires; unsigned long long sum_sched_runtime, sched_expires; struct task_struct *t; struct list_head *timers = sig->cpu_timers; /* * Don't sample the current process CPU clocks if there are no timers. */ if (list_empty(&timers[CPUCLOCK_PROF]) && cputime_eq(sig->it_prof_expires, cputime_zero) && sig->rlim[RLIMIT_CPU].rlim_cur == RLIM_INFINITY && list_empty(&timers[CPUCLOCK_VIRT]) && cputime_eq(sig->it_virt_expires, cputime_zero) && list_empty(&timers[CPUCLOCK_SCHED])) return; /* * Collect the current process totals. */ utime = sig->utime; stime = sig->stime; sum_sched_runtime = sig->sum_sched_runtime; t = tsk; do { utime = cputime_add(utime, t->utime); stime = cputime_add(stime, t->stime); sum_sched_runtime += t->se.sum_exec_runtime; t = next_thread(t); } while (t != tsk); ptime = cputime_add(utime, stime); maxfire = 20; prof_expires = cputime_zero; while (!list_empty(timers)) { struct cpu_timer_list *t = list_first_entry(timers, struct cpu_timer_list, entry); if (!--maxfire || cputime_lt(ptime, t->expires.cpu)) { prof_expires = t->expires.cpu; break; } t->firing = 1; list_move_tail(&t->entry, firing); } ++timers; maxfire = 20; virt_expires = cputime_zero; while (!list_empty(timers)) { struct cpu_timer_list *t = list_first_entry(timers, struct cpu_timer_list, entry); if (!--maxfire || cputime_lt(utime, t->expires.cpu)) { virt_expires = t->expires.cpu; break; } t->firing = 1; list_move_tail(&t->entry, firing); } ++timers; maxfire = 20; sched_expires = 0; while (!list_empty(timers)) { struct cpu_timer_list *t = list_first_entry(timers, struct cpu_timer_list, entry); if (!--maxfire || sum_sched_runtime < t->expires.sched) { sched_expires = t->expires.sched; break; } t->firing = 1; list_move_tail(&t->entry, firing); } /* * Check for the special case process timers. */ if (!cputime_eq(sig->it_prof_expires, cputime_zero)) { if (cputime_ge(ptime, sig->it_prof_expires)) { /* ITIMER_PROF fires and reloads. */ sig->it_prof_expires = sig->it_prof_incr; if (!cputime_eq(sig->it_prof_expires, cputime_zero)) { sig->it_prof_expires = cputime_add( sig->it_prof_expires, ptime); } __group_send_sig_info(SIGPROF, SEND_SIG_PRIV, tsk); } if (!cputime_eq(sig->it_prof_expires, cputime_zero) && (cputime_eq(prof_expires, cputime_zero) || cputime_lt(sig->it_prof_expires, prof_expires))) { prof_expires = sig->it_prof_expires; } } if (!cputime_eq(sig->it_virt_expires, cputime_zero)) { if (cputime_ge(utime, sig->it_virt_expires)) { /* ITIMER_VIRTUAL fires and reloads. */ sig->it_virt_expires = sig->it_virt_incr; if (!cputime_eq(sig->it_virt_expires, cputime_zero)) { sig->it_virt_expires = cputime_add( sig->it_virt_expires, utime); } __group_send_sig_info(SIGVTALRM, SEND_SIG_PRIV, tsk); } if (!cputime_eq(sig->it_virt_expires, cputime_zero) && (cputime_eq(virt_expires, cputime_zero) || cputime_lt(sig->it_virt_expires, virt_expires))) { virt_expires = sig->it_virt_expires; } } if (sig->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY) { unsigned long psecs = cputime_to_secs(ptime); cputime_t x; if (psecs >= sig->rlim[RLIMIT_CPU].rlim_max) { /* * 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 >= sig->rlim[RLIMIT_CPU].rlim_cur) { /* * At the soft limit, send a SIGXCPU every second. */ __group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk); if (sig->rlim[RLIMIT_CPU].rlim_cur < sig->rlim[RLIMIT_CPU].rlim_max) { sig->rlim[RLIMIT_CPU].rlim_cur++; } } x = secs_to_cputime(sig->rlim[RLIMIT_CPU].rlim_cur); if (cputime_eq(prof_expires, cputime_zero) || cputime_lt(x, prof_expires)) { prof_expires = x; } } if (!cputime_eq(prof_expires, cputime_zero) || !cputime_eq(virt_expires, cputime_zero) || sched_expires != 0) { /* * Rebalance the threads' expiry times for the remaining * process CPU timers. */ cputime_t prof_left, virt_left, ticks; unsigned long long sched_left, sched; const unsigned int nthreads = atomic_read(&sig->live); if (!nthreads) return; prof_left = cputime_sub(prof_expires, utime); prof_left = cputime_sub(prof_left, stime); prof_left = cputime_div_non_zero(prof_left, nthreads); virt_left = cputime_sub(virt_expires, utime); virt_left = cputime_div_non_zero(virt_left, nthreads); if (sched_expires) { sched_left = sched_expires - sum_sched_runtime; do_div(sched_left, nthreads); sched_left = max_t(unsigned long long, sched_left, 1); } else { sched_left = 0; } t = tsk; do { if (unlikely(t->flags & PF_EXITING)) continue; ticks = cputime_add(cputime_add(t->utime, t->stime), prof_left); if (!cputime_eq(prof_expires, cputime_zero) && (cputime_eq(t->it_prof_expires, cputime_zero) || cputime_gt(t->it_prof_expires, ticks))) { t->it_prof_expires = ticks; } ticks = cputime_add(t->utime, virt_left); if (!cputime_eq(virt_expires, cputime_zero) && (cputime_eq(t->it_virt_expires, cputime_zero) || cputime_gt(t->it_virt_expires, ticks))) { t->it_virt_expires = ticks; } sched = t->se.sum_exec_runtime + sched_left; if (sched_expires && (t->it_sched_expires == 0 || t->it_sched_expires > sched)) { t->it_sched_expires = sched; } } while ((t = next_thread(t)) != tsk); } } /* * 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. */ } else { read_lock(&tasklist_lock); if (unlikely(p->signal == 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; } cpu_clock_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. */ arm_timer(timer, now); out_unlock: read_unlock(&tasklist_lock); out: timer->it_overrun_last = timer->it_overrun; timer->it_overrun = -1; ++timer->it_requeue_pending; } /* * 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; BUG_ON(!irqs_disabled()); #define UNEXPIRED(clock) \ (cputime_eq(tsk->it_##clock##_expires, cputime_zero) || \ cputime_lt(clock##_ticks(tsk), tsk->it_##clock##_expires)) if (UNEXPIRED(prof) && UNEXPIRED(virt) && (tsk->it_sched_expires == 0 || tsk->se.sum_exec_runtime < tsk->it_sched_expires)) return; #undef UNEXPIRED /* * Double-check with locks held. */ read_lock(&tasklist_lock); if (likely(tsk->signal != NULL)) { spin_lock(&tsk->sighand->siglock); /* * Here we take off tsk->cpu_timers[N] and tsk->signal->cpu_timers[N] * all the timers that are firing, and put them on the firing list. */ check_thread_timers(tsk, &firing); 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. */ spin_unlock(&tsk->sighand->siglock); } read_unlock(&tasklist_lock); /* * Now that all the timers on our list have the firing flag, * noone 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 firing; spin_lock(&timer->it_lock); list_del_init(&timer->it.cpu.entry); 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(firing >= 0)) { cpu_timer_fire(timer); } spin_unlock(&timer->it_lock); } } /* * Set one of the process-wide special case CPU timers. * The tasklist_lock and tsk->sighand->siglock must be held by the caller. * The oldval argument is null for the RLIMIT_CPU timer, where *newval is * absolute; non-null for ITIMER_*, where *newval is relative and we update * it to be absolute, *oldval is absolute and we update it to be relative. */ void set_process_cpu_timer(struct task_struct *tsk, unsigned int clock_idx, cputime_t *newval, cputime_t *oldval) { union cpu_time_count now; struct list_head *head; BUG_ON(clock_idx == CPUCLOCK_SCHED); cpu_clock_sample_group_locked(clock_idx, tsk, &now); if (oldval) { if (!cputime_eq(*oldval, cputime_zero)) { if (cputime_le(*oldval, now.cpu)) { /* Just about to fire. */ *oldval = jiffies_to_cputime(1); } else { *oldval = cputime_sub(*oldval, now.cpu); } } if (cputime_eq(*newval, cputime_zero)) return; *newval = cputime_add(*newval, now.cpu); /* * If the RLIMIT_CPU timer will expire before the * ITIMER_PROF timer, we have nothing else to do. */ if (tsk->signal->rlim[RLIMIT_CPU].rlim_cur < cputime_to_secs(*newval)) return; } /* * Check whether there are any process timers already set to fire * before this one. If so, we don't have anything more to do. */ head = &tsk->signal->cpu_timers[clock_idx]; if (list_empty(head) || cputime_ge(list_first_entry(head, struct cpu_timer_list, entry)->expires.cpu, *newval)) { /* * Rejigger each thread's expiry time so that one will * notice before we hit the process-cumulative expiry time. */ union cpu_time_count expires = { .sched = 0 }; expires.cpu = *newval; process_timer_rebalance(tsk, clock_idx, expires, now); } } 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; } 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 != NULL && copy_to_user(rmtp, &it.it_value, sizeof *rmtp)) return -EFAULT; restart_block->fn = posix_cpu_nsleep_restart; restart_block->arg0 = which_clock; restart_block->arg1 = (unsigned long) rmtp; restart_block->arg2 = rqtp->tv_sec; restart_block->arg3 = rqtp->tv_nsec; } return error; } long posix_cpu_nsleep_restart(struct restart_block *restart_block) { clockid_t which_clock = restart_block->arg0; struct timespec __user *rmtp; struct timespec t; struct itimerspec it; int error; rmtp = (struct timespec __user *) restart_block->arg1; t.tv_sec = restart_block->arg2; t.tv_nsec = restart_block->arg3; restart_block->fn = do_no_restart_syscall; error = do_cpu_nanosleep(which_clock, TIMER_ABSTIME, &t, &it); if (error == -ERESTART_RESTARTBLOCK) { /* * Report back to the user the time still remaining. */ if (rmtp != NULL && copy_to_user(rmtp, &it.it_value, sizeof *rmtp)) return -EFAULT; restart_block->fn = posix_cpu_nsleep_restart; restart_block->arg0 = which_clock; restart_block->arg1 = (unsigned long) rmtp; restart_block->arg2 = t.tv_sec; restart_block->arg3 = t.tv_nsec; } 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); } static int thread_cpu_nsleep(const clockid_t which_clock, int flags, struct timespec *rqtp, struct timespec __user *rmtp) { return -EINVAL; } static long thread_cpu_nsleep_restart(struct restart_block *restart_block) { return -EINVAL; } static __init int init_posix_cpu_timers(void) { struct k_clock process = { .clock_getres = process_cpu_clock_getres, .clock_get = process_cpu_clock_get, .clock_set = do_posix_clock_nosettime, .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, .clock_set = do_posix_clock_nosettime, .timer_create = thread_cpu_timer_create, .nsleep = thread_cpu_nsleep, .nsleep_restart = thread_cpu_nsleep_restart, }; register_posix_clock(CLOCK_PROCESS_CPUTIME_ID, &process); register_posix_clock(CLOCK_THREAD_CPUTIME_ID, &thread); return 0; } __initcall(init_posix_cpu_timers);