From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: linux-rt-users@vger.kernel.org
Cc: linux-kernel@vger.kernel.org,
Thomas Gleixner <tglx@linutronix.de>,
Steven Rostedt <rostedt@goodmis.org>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
stable-rt@vger.kernel.org
Subject: [PATCH RT 1/3] alarmtimer: Prevent live lock in alarm_cancel()
Date: Wed, 28 Mar 2018 12:07:44 +0200 [thread overview]
Message-ID: <20180328100746.18668-1-bigeasy@linutronix.de> (raw)
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 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
next reply other threads:[~2018-03-28 10:07 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-28 10:07 Sebastian Andrzej Siewior [this message]
2018-03-28 10:07 ` [PATCH RT 2/3] posix-timers: user proper timer while waiting for alarmtimer Sebastian Andrzej Siewior
2018-03-28 10:28 ` [PATCH RT 2/3 v2] " Sebastian Andrzej Siewior
2018-03-28 10:07 ` [PATCH RT 3/3] posix-timers: move the rcu head out of the union Sebastian Andrzej Siewior
2018-03-28 10:29 ` [PATCH RT 3/3 v2] " Sebastian Andrzej Siewior
2018-04-03 18:32 ` [PATCH RT 1/3] alarmtimer: Prevent live lock in alarm_cancel() Daniel Wagner
2018-04-04 7:37 ` Sebastian Andrzej Siewior
-- strict thread matches above, loose matches on Subject: below --
2018-05-04 13:55 [PATCH RT 0/3] 4.4.131-rt148-rc1 Daniel Wagner
2018-05-04 13:55 ` [PATCH RT 1/3] alarmtimer: Prevent live lock in alarm_cancel() Daniel Wagner
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