diff options
| author |   Thomas Gleixner <tglx@linutronix.de> | 2019-08-02 07:35:59 +0200 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2019-08-20 22:05:46 +0200 |
| commit | ec8f954a40da8cd3d159713b608e901f0cd909a9 (patch) | |
| tree | a6099be5d308424ad07e3332f45cc3b757b28e90 /kernel/time/alarmtimer.c | |
| parent | posix-timers: Move rcu_head out of it union (diff) | |
| download | linux-dev-ec8f954a40da8cd3d159713b608e901f0cd909a9.tar.xz linux-dev-ec8f954a40da8cd3d159713b608e901f0cd909a9.zip | |
posix-timers: Use a callback for cancel synchronization on PREEMPT_RT
Posix timer delete retry loops are affected by the same priority inversion
and live lock issues as the other timers.
Provide a RT specific synchronization function which keeps a reference to
the timer by holding rcu read lock to prevent the timer from being freed,
dropping the timer lock and invoking the timer specific wait function via a
new callback.
This does not yet cover posix CPU timers because they need more special
treatment on PREEMPT_RT.
[ This is folded into the original attempt which did not use a callback. ]
Originally-by: Anna-Maria Gleixenr <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lkml.kernel.org/r/20190819143801.656864506@linutronix.de
Diffstat (limited to 'kernel/time/alarmtimer.c')
| -rw-r--r-- | kernel/time/alarmtimer.c | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c index 36947449dba2..ec32876e284d 100644 --- a/kernel/time/alarmtimer.c +++ b/kernel/time/alarmtimer.c @@ -606,6 +606,19 @@ static int alarm_timer_try_to_cancel(struct k_itimer *timr) } /** + * alarm_timer_wait_running - Posix timer callback to wait for a timer + * @timr: Pointer to the posixtimer data struct + * + * Called from the core code when timer cancel detected that the callback + * is running. @timr is unlocked and rcu read lock is held to prevent it + * from being freed. + */ +static void alarm_timer_wait_running(struct k_itimer *timr) +{ + hrtimer_cancel_wait_running(&timr->it.alarm.alarmtimer.timer); +} + +/** * alarm_timer_arm - Posix timer callback to arm a timer * @timr: Pointer to the posixtimer data struct * @expires: The new expiry time @@ -834,6 +847,7 @@ const struct k_clock alarm_clock = { .timer_forward = alarm_timer_forward, .timer_remaining = alarm_timer_remaining, .timer_try_to_cancel = alarm_timer_try_to_cancel, + .timer_wait_running = alarm_timer_wait_running, .nsleep = alarm_timer_nsleep, }; #endif /* CONFIG_POSIX_TIMERS */ |