diff options
Diffstat (limited to 'kernel/time/posix-timers.c')
| -rw-r--r-- | kernel/time/posix-timers.c | 61 |
1 files changed, 50 insertions, 11 deletions
diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c index d7f2d91acdac..0ec5b7a1d769 100644 --- a/kernel/time/posix-timers.c +++ b/kernel/time/posix-timers.c @@ -442,7 +442,7 @@ static struct k_itimer * alloc_posix_timer(void) static void k_itimer_rcu_free(struct rcu_head *head) { - struct k_itimer *tmr = container_of(head, struct k_itimer, it.rcu); + struct k_itimer *tmr = container_of(head, struct k_itimer, rcu); kmem_cache_free(posix_timers_cache, tmr); } @@ -459,7 +459,7 @@ static void release_posix_timer(struct k_itimer *tmr, int it_id_set) } put_pid(tmr->it_pid); sigqueue_free(tmr->sigq); - call_rcu(&tmr->it.rcu, k_itimer_rcu_free); + call_rcu(&tmr->rcu, k_itimer_rcu_free); } static int common_timer_create(struct k_itimer *new_timer) @@ -805,6 +805,35 @@ static int common_hrtimer_try_to_cancel(struct k_itimer *timr) return hrtimer_try_to_cancel(&timr->it.real.timer); } +static void common_timer_wait_running(struct k_itimer *timer) +{ + hrtimer_cancel_wait_running(&timer->it.real.timer); +} + +/* + * On PREEMPT_RT this prevent priority inversion against softirq kthread in + * case it gets preempted while executing a timer callback. See comments in + * hrtimer_cancel_wait_running. For PREEMPT_RT=n this just results in a + * cpu_relax(). + */ +static struct k_itimer *timer_wait_running(struct k_itimer *timer, + unsigned long *flags) +{ + const struct k_clock *kc = READ_ONCE(timer->kclock); + timer_t timer_id = READ_ONCE(timer->it_id); + + /* Prevent kfree(timer) after dropping the lock */ + rcu_read_lock(); + unlock_timer(timer, *flags); + + if (!WARN_ON_ONCE(!kc->timer_wait_running)) + kc->timer_wait_running(timer); + + rcu_read_unlock(); + /* Relock the timer. It might be not longer hashed. */ + return lock_timer(timer_id, flags); +} + /* Set a POSIX.1b interval timer. */ int common_timer_set(struct k_itimer *timr, int flags, struct itimerspec64 *new_setting, @@ -844,13 +873,13 @@ int common_timer_set(struct k_itimer *timr, int flags, return 0; } -static int do_timer_settime(timer_t timer_id, int flags, +static int do_timer_settime(timer_t timer_id, int tmr_flags, struct itimerspec64 *new_spec64, struct itimerspec64 *old_spec64) { const struct k_clock *kc; struct k_itimer *timr; - unsigned long flag; + unsigned long flags; int error = 0; if (!timespec64_valid(&new_spec64->it_interval) || @@ -859,8 +888,9 @@ static int do_timer_settime(timer_t timer_id, int flags, if (old_spec64) memset(old_spec64, 0, sizeof(*old_spec64)); + + timr = lock_timer(timer_id, &flags); retry: - timr = lock_timer(timer_id, &flag); if (!timr) return -EINVAL; @@ -868,13 +898,16 @@ retry: if (WARN_ON_ONCE(!kc || !kc->timer_set)) error = -EINVAL; else - error = kc->timer_set(timr, flags, new_spec64, old_spec64); + error = kc->timer_set(timr, tmr_flags, new_spec64, old_spec64); - unlock_timer(timr, flag); if (error == TIMER_RETRY) { - old_spec64 = NULL; // We already got the old time... + // We already got the old time... + old_spec64 = NULL; + /* Unlocks and relocks the timer if it still exists */ + timr = timer_wait_running(timr, &flags); goto retry; } + unlock_timer(timr, flags); return error; } @@ -951,13 +984,15 @@ SYSCALL_DEFINE1(timer_delete, timer_t, timer_id) struct k_itimer *timer; unsigned long flags; -retry_delete: timer = lock_timer(timer_id, &flags); + +retry_delete: if (!timer) return -EINVAL; - if (timer_delete_hook(timer) == TIMER_RETRY) { - unlock_timer(timer, flags); + if (unlikely(timer_delete_hook(timer) == TIMER_RETRY)) { + /* Unlocks and relocks the timer if it still exists */ + timer = timer_wait_running(timer, &flags); goto retry_delete; } @@ -1238,6 +1273,7 @@ static const struct k_clock clock_realtime = { .timer_forward = common_hrtimer_forward, .timer_remaining = common_hrtimer_remaining, .timer_try_to_cancel = common_hrtimer_try_to_cancel, + .timer_wait_running = common_timer_wait_running, .timer_arm = common_hrtimer_arm, }; @@ -1253,6 +1289,7 @@ static const struct k_clock clock_monotonic = { .timer_forward = common_hrtimer_forward, .timer_remaining = common_hrtimer_remaining, .timer_try_to_cancel = common_hrtimer_try_to_cancel, + .timer_wait_running = common_timer_wait_running, .timer_arm = common_hrtimer_arm, }; @@ -1283,6 +1320,7 @@ static const struct k_clock clock_tai = { .timer_forward = common_hrtimer_forward, .timer_remaining = common_hrtimer_remaining, .timer_try_to_cancel = common_hrtimer_try_to_cancel, + .timer_wait_running = common_timer_wait_running, .timer_arm = common_hrtimer_arm, }; @@ -1298,6 +1336,7 @@ static const struct k_clock clock_boottime = { .timer_forward = common_hrtimer_forward, .timer_remaining = common_hrtimer_remaining, .timer_try_to_cancel = common_hrtimer_try_to_cancel, + .timer_wait_running = common_timer_wait_running, .timer_arm = common_hrtimer_arm, }; |