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Subject[PATCH RT 1/3] alarmtimer: Prevent live lock in alarm_cancel()
Date
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

If alarm_try_to_cancel() requires a retry, then depending on the
priority setting the retry loop might prevent timer callback completion
on RT. Prevent that by waiting for completion on RT, no change for a
non RT kernel.

Cc: stable-rt@vger.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
kernel/time/alarmtimer.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index 6fcc367ad531..9d5eac2c9275 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -392,7 +392,7 @@ int alarm_cancel(struct alarm *alarm)
int ret = alarm_try_to_cancel(alarm);
if (ret >= 0)
return ret;
- cpu_relax();
+ hrtimer_wait_for_timer(&alarm->timer);
}
}
EXPORT_SYMBOL_GPL(alarm_cancel);
--
2.14.3
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