[PATCH RT 1/3] alarmtimer: Prevent live lock in alarm_cancel()

[Sebastian Andrzej Siewior]

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...@vger.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bige...@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 ec09ce9a6012..ede5ef787865 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -429,7 +429,7 @@ 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);
-- 
2.16.3