From: Daniel Wagner <wagi@monom.org>
To: linux-rt-users@vger.kernel.org
Cc: linux-kernel@vger.kernel.org,
Steven Rostedt <rostedt@goodmis.org>,
Thomas Gleixner <tglx@linutronix.de>,
Carsten Emde <C.Emde@osadl.org>, John Kacur <jkacur@redhat.com>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Daniel Wagner <daniel.wagner@siemens.com>,
Tom Zanussi <tom.zanussi@linux.intel.com>,
Julia Cartwright <julia@ni.com>,
stable-rt@vger.kernel.org
Subject: [PATCH RT 1/3] alarmtimer: Prevent live lock in alarm_cancel()
Date: Fri, 4 May 2018 15:55:14 +0200 [thread overview]
Message-ID: <20180504135516.32601-2-wagi@monom.org> (raw)
In-Reply-To: <20180504135516.32601-1-wagi@monom.org>
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
next prev parent reply other threads:[~2018-05-04 13:57 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-04 13:55 [PATCH RT 0/3] 4.4.131-rt148-rc1 Daniel Wagner
2018-05-04 13:55 ` Daniel Wagner [this message]
2018-05-04 13:55 ` [PATCH RT 2/3] posix-timers: move the rcu head out of the union Daniel Wagner
2018-05-04 13:55 ` [PATCH RT 3/3] Linux 4.4.131-rt148-rc1 Daniel Wagner
-- strict thread matches above, loose matches on Subject: below --
2018-03-28 10:07 [PATCH RT 1/3] alarmtimer: Prevent live lock in alarm_cancel() Sebastian Andrzej Siewior
2018-04-03 18:32 ` Daniel Wagner
2018-04-04 7:37 ` Sebastian Andrzej Siewior
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