diff options
Diffstat (limited to 'kernel/posix-cpu-timers.c')
| -rw-r--r-- | kernel/posix-cpu-timers.c | 126 |
1 files changed, 73 insertions, 53 deletions
diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c index b3f3edc475de..91a894264941 100644 --- a/kernel/posix-cpu-timers.c +++ b/kernel/posix-cpu-timers.c @@ -91,7 +91,7 @@ static inline union cpu_time_count cpu_time_sub(clockid_t which_clock, * Update expiry time from increment, and increase overrun count, * given the current clock sample. */ -static inline void bump_cpu_timer(struct k_itimer *timer, +static void bump_cpu_timer(struct k_itimer *timer, union cpu_time_count now) { int i; @@ -110,7 +110,7 @@ static inline void bump_cpu_timer(struct k_itimer *timer, for (i = 0; incr < delta - incr; i++) incr = incr << 1; for (; i >= 0; incr >>= 1, i--) { - if (delta <= incr) + if (delta < incr) continue; timer->it.cpu.expires.sched += incr; timer->it_overrun += 1 << i; @@ -128,7 +128,7 @@ static inline void bump_cpu_timer(struct k_itimer *timer, 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_le(delta, incr)) + if (cputime_lt(delta, incr)) continue; timer->it.cpu.expires.cpu = cputime_add(timer->it.cpu.expires.cpu, incr); @@ -380,28 +380,31 @@ int posix_cpu_timer_create(struct k_itimer *new_timer) int posix_cpu_timer_del(struct k_itimer *timer) { struct task_struct *p = timer->it.cpu.task; + int ret = 0; - if (timer->it.cpu.firing) - return TIMER_RETRY; - - if (unlikely(p == NULL)) - return 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); - spin_lock(&p->sighand->siglock); - if (!list_empty(&timer->it.cpu.entry)) { - /* - * Take us off the task's timer list. We don't need to - * take tasklist_lock and check for the task being reaped. - * If it was reaped, it already called posix_cpu_timers_exit - * and posix_cpu_timers_exit_group to clear all the timers - * that pointed to it. - */ - list_del(&timer->it.cpu.entry); - put_task_struct(p); + if (!ret) + put_task_struct(p); } - spin_unlock(&p->sighand->siglock); - return 0; + return ret; } /* @@ -418,8 +421,6 @@ static void cleanup_timers(struct list_head *head, cputime_t ptime = cputime_add(utime, stime); list_for_each_entry_safe(timer, next, head, entry) { - put_task_struct(timer->task); - timer->task = NULL; list_del_init(&timer->entry); if (cputime_lt(timer->expires.cpu, ptime)) { timer->expires.cpu = cputime_zero; @@ -431,8 +432,6 @@ static void cleanup_timers(struct list_head *head, ++head; list_for_each_entry_safe(timer, next, head, entry) { - put_task_struct(timer->task); - timer->task = NULL; list_del_init(&timer->entry); if (cputime_lt(timer->expires.cpu, utime)) { timer->expires.cpu = cputime_zero; @@ -444,8 +443,6 @@ static void cleanup_timers(struct list_head *head, ++head; list_for_each_entry_safe(timer, next, head, entry) { - put_task_struct(timer->task); - timer->task = NULL; list_del_init(&timer->entry); if (timer->expires.sched < sched_time) { timer->expires.sched = 0; @@ -489,6 +486,9 @@ static void process_timer_rebalance(struct task_struct *p, struct task_struct *t = p; unsigned int nthreads = atomic_read(&p->signal->live); + if (!nthreads) + return; + switch (clock_idx) { default: BUG(); @@ -497,7 +497,7 @@ static void process_timer_rebalance(struct task_struct *p, left = cputime_div(cputime_sub(expires.cpu, val.cpu), nthreads); do { - if (!unlikely(t->exit_state)) { + if (!unlikely(t->flags & PF_EXITING)) { ticks = cputime_add(prof_ticks(t), left); if (cputime_eq(t->it_prof_expires, cputime_zero) || @@ -512,7 +512,7 @@ static void process_timer_rebalance(struct task_struct *p, left = cputime_div(cputime_sub(expires.cpu, val.cpu), nthreads); do { - if (!unlikely(t->exit_state)) { + if (!unlikely(t->flags & PF_EXITING)) { ticks = cputime_add(virt_ticks(t), left); if (cputime_eq(t->it_virt_expires, cputime_zero) || @@ -527,7 +527,7 @@ static void process_timer_rebalance(struct task_struct *p, nsleft = expires.sched - val.sched; do_div(nsleft, nthreads); do { - if (!unlikely(t->exit_state)) { + if (!unlikely(t->flags & PF_EXITING)) { ns = t->sched_time + nsleft; if (t->it_sched_expires == 0 || t->it_sched_expires > ns) { @@ -566,6 +566,9 @@ static void arm_timer(struct k_itimer *timer, union cpu_time_count now) struct cpu_timer_list *next; unsigned long i; + if (CPUCLOCK_PERTHREAD(timer->it_clock) && (p->flags & PF_EXITING)) + return; + head = (CPUCLOCK_PERTHREAD(timer->it_clock) ? p->cpu_timers : p->signal->cpu_timers); head += CPUCLOCK_WHICH(timer->it_clock); @@ -576,17 +579,15 @@ static void arm_timer(struct k_itimer *timer, union cpu_time_count now) listpos = head; if (CPUCLOCK_WHICH(timer->it_clock) == CPUCLOCK_SCHED) { list_for_each_entry(next, head, entry) { - if (next->expires.sched > nt->expires.sched) { - listpos = &next->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)) { - listpos = &next->entry; + if (cputime_gt(next->expires.cpu, nt->expires.cpu)) break; - } + listpos = &next->entry; } } list_add(&nt->entry, listpos); @@ -730,9 +731,15 @@ int posix_cpu_timer_set(struct k_itimer *timer, int flags, * 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; - list_del_init(&timer->it.cpu.entry); + 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); /* @@ -780,7 +787,7 @@ int posix_cpu_timer_set(struct k_itimer *timer, int flags, } } - if (unlikely(timer->it.cpu.firing)) { + if (unlikely(ret)) { /* * We are colliding with the timer actually firing. * Punt after filling in the timer's old value, and @@ -788,8 +795,6 @@ int posix_cpu_timer_set(struct k_itimer *timer, int flags, * it as an overrun (thanks to bump_cpu_timer above). */ read_unlock(&tasklist_lock); - timer->it.cpu.firing = -1; - ret = TIMER_RETRY; goto out; } @@ -955,14 +960,16 @@ void posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec *itp) 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_entry(timers->next, struct cpu_timer_list, entry); - if (cputime_lt(prof_ticks(tsk), t->expires.cpu)) { + if (!--maxfire || cputime_lt(prof_ticks(tsk), t->expires.cpu)) { tsk->it_prof_expires = t->expires.cpu; break; } @@ -971,12 +978,13 @@ static void check_thread_timers(struct task_struct *tsk, } ++timers; + maxfire = 20; tsk->it_virt_expires = cputime_zero; while (!list_empty(timers)) { struct cpu_timer_list *t = list_entry(timers->next, struct cpu_timer_list, entry); - if (cputime_lt(virt_ticks(tsk), t->expires.cpu)) { + if (!--maxfire || cputime_lt(virt_ticks(tsk), t->expires.cpu)) { tsk->it_virt_expires = t->expires.cpu; break; } @@ -985,12 +993,13 @@ static void check_thread_timers(struct task_struct *tsk, } ++timers; + maxfire = 20; tsk->it_sched_expires = 0; while (!list_empty(timers)) { struct cpu_timer_list *t = list_entry(timers->next, struct cpu_timer_list, entry); - if (tsk->sched_time < t->expires.sched) { + if (!--maxfire || tsk->sched_time < t->expires.sched) { tsk->it_sched_expires = t->expires.sched; break; } @@ -1007,6 +1016,7 @@ static void check_thread_timers(struct task_struct *tsk, 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 sched_time, sched_expires; @@ -1039,12 +1049,13 @@ static void check_process_timers(struct task_struct *tsk, } while (t != tsk); ptime = cputime_add(utime, stime); + maxfire = 20; prof_expires = cputime_zero; while (!list_empty(timers)) { struct cpu_timer_list *t = list_entry(timers->next, struct cpu_timer_list, entry); - if (cputime_lt(ptime, t->expires.cpu)) { + if (!--maxfire || cputime_lt(ptime, t->expires.cpu)) { prof_expires = t->expires.cpu; break; } @@ -1053,12 +1064,13 @@ static void check_process_timers(struct task_struct *tsk, } ++timers; + maxfire = 20; virt_expires = cputime_zero; while (!list_empty(timers)) { struct cpu_timer_list *t = list_entry(timers->next, struct cpu_timer_list, entry); - if (cputime_lt(utime, t->expires.cpu)) { + if (!--maxfire || cputime_lt(utime, t->expires.cpu)) { virt_expires = t->expires.cpu; break; } @@ -1067,12 +1079,13 @@ static void check_process_timers(struct task_struct *tsk, } ++timers; + maxfire = 20; sched_expires = 0; while (!list_empty(timers)) { struct cpu_timer_list *t = list_entry(timers->next, struct cpu_timer_list, entry); - if (sched_time < t->expires.sched) { + if (!--maxfire || sched_time < t->expires.sched) { sched_expires = t->expires.sched; break; } @@ -1155,6 +1168,9 @@ static void check_process_timers(struct task_struct *tsk, 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(prof_left, nthreads); @@ -1191,7 +1207,7 @@ static void check_process_timers(struct task_struct *tsk, do { t = next_thread(t); - } while (unlikely(t->exit_state)); + } while (unlikely(t->flags & PF_EXITING)); } while (t != tsk); } } @@ -1209,7 +1225,7 @@ void posix_cpu_timer_schedule(struct k_itimer *timer) /* * The task was cleaned up already, no future firings. */ - return; + goto out; /* * Fetch the current sample and update the timer's expiry time. @@ -1219,7 +1235,7 @@ void posix_cpu_timer_schedule(struct k_itimer *timer) bump_cpu_timer(timer, now); if (unlikely(p->exit_state)) { clear_dead_task(timer, now); - return; + goto out; } read_lock(&tasklist_lock); /* arm_timer needs it. */ } else { @@ -1232,8 +1248,7 @@ void posix_cpu_timer_schedule(struct k_itimer *timer) put_task_struct(p); timer->it.cpu.task = p = NULL; timer->it.cpu.expires.sched = 0; - read_unlock(&tasklist_lock); - return; + goto out_unlock; } else if (unlikely(p->exit_state) && thread_group_empty(p)) { /* * We've noticed that the thread is dead, but @@ -1241,8 +1256,7 @@ void posix_cpu_timer_schedule(struct k_itimer *timer) * drop our task ref. */ clear_dead_task(timer, now); - read_unlock(&tasklist_lock); - return; + goto out_unlock; } cpu_clock_sample_group(timer->it_clock, p, &now); bump_cpu_timer(timer, now); @@ -1254,7 +1268,13 @@ void posix_cpu_timer_schedule(struct k_itimer *timer) */ 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; } /* |