diff options
| author | John Stultz <john.stultz@linaro.org> | 2011-08-10 12:41:36 -0700 |
|---|---|---|
| committer | John Stultz <john.stultz@linaro.org> | 2011-08-10 14:55:29 -0700 |
| commit | 9082c465a5403f4a98734193e078552991a2e283 (patch) | |
| tree | 387e564f326488abe9ee84b0c723294ea573de1e | |
| parent | a28cde81ab13cc251748a4c4ef06883dd09a10ea (diff) | |
alarmtimers: Add try_to_cancel functionality
There's a number of edge cases when cancelling a alarm, so
to be sure we accurately do so, introduce try_to_cancel, which
returns proper failure errors if it cannot. Also modify cancel
to spin until the alarm is properly disabled.
CC: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
| -rw-r--r-- | include/linux/alarmtimer.h | 3 | ||||
| -rw-r--r-- | kernel/time/alarmtimer.c | 43 |
2 files changed, 39 insertions, 7 deletions
diff --git a/include/linux/alarmtimer.h b/include/linux/alarmtimer.h index 304124a6c982..975009e1cbe6 100644 --- a/include/linux/alarmtimer.h +++ b/include/linux/alarmtimer.h @@ -44,7 +44,8 @@ struct alarm { void alarm_init(struct alarm *alarm, enum alarmtimer_type type, enum alarmtimer_restart (*function)(struct alarm *, ktime_t)); void alarm_start(struct alarm *alarm, ktime_t start); -void alarm_cancel(struct alarm *alarm); +int alarm_try_to_cancel(struct alarm *alarm); +int alarm_cancel(struct alarm *alarm); u64 alarm_forward(struct alarm *alarm, ktime_t now, ktime_t interval); diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c index 5b14cc29b6a6..bdb7342b6896 100644 --- a/kernel/time/alarmtimer.c +++ b/kernel/time/alarmtimer.c @@ -336,21 +336,49 @@ void alarm_start(struct alarm *alarm, ktime_t start) } /** - * alarm_cancel - Tries to cancel an alarm timer + * alarm_try_to_cancel - Tries to cancel an alarm timer * @alarm: ptr to alarm to be canceled + * + * Returns 1 if the timer was canceled, 0 if it was not running, + * and -1 if the callback was running */ -void alarm_cancel(struct alarm *alarm) +int alarm_try_to_cancel(struct alarm *alarm) { struct alarm_base *base = &alarm_bases[alarm->type]; unsigned long flags; - + int ret = -1; spin_lock_irqsave(&base->lock, flags); - if (alarmtimer_is_queued(alarm)) + + if (alarmtimer_callback_running(alarm)) + goto out; + + if (alarmtimer_is_queued(alarm)) { alarmtimer_remove(base, alarm); + ret = 1; + } else + ret = 0; +out: spin_unlock_irqrestore(&base->lock, flags); + return ret; } +/** + * alarm_cancel - Spins trying to cancel an alarm timer until it is done + * @alarm: ptr to alarm to be canceled + * + * Returns 1 if the timer was canceled, 0 if it was not active. + */ +int alarm_cancel(struct alarm *alarm) +{ + for (;;) { + int ret = alarm_try_to_cancel(alarm); + if (ret >= 0) + return ret; + cpu_relax(); + } +} + u64 alarm_forward(struct alarm *alarm, ktime_t now, ktime_t interval) { @@ -510,7 +538,9 @@ static int alarm_timer_del(struct k_itimer *timr) if (!rtcdev) return -ENOTSUPP; - alarm_cancel(&timr->it.alarm.alarmtimer); + if (alarm_try_to_cancel(&timr->it.alarm.alarmtimer) < 0) + return TIMER_RETRY; + return 0; } @@ -534,7 +564,8 @@ static int alarm_timer_set(struct k_itimer *timr, int flags, alarm_timer_get(timr, old_setting); /* If the timer was already set, cancel it */ - alarm_cancel(&timr->it.alarm.alarmtimer); + if (alarm_try_to_cancel(&timr->it.alarm.alarmtimer) < 0) + return TIMER_RETRY; /* start the timer */ timr->it.alarm.interval = timespec_to_ktime(new_setting->it_interval); |