From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751748AbeEDN5B (ORCPT ); Fri, 4 May 2018 09:57:01 -0400 Received: from mail.monom.org ([188.138.9.77]:44006 "EHLO mail.monom.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751948AbeEDNzZ (ORCPT ); Fri, 4 May 2018 09:55:25 -0400 From: Daniel Wagner To: linux-rt-users@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Steven Rostedt , Thomas Gleixner , Carsten Emde , John Kacur , Sebastian Andrzej Siewior , Daniel Wagner , Tom Zanussi , Julia Cartwright , 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 Message-Id: <20180504135516.32601-2-wagi@monom.org> X-Mailer: git-send-email 2.14.3 In-Reply-To: <20180504135516.32601-1-wagi@monom.org> References: <20180504135516.32601-1-wagi@monom.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: 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-rt@vger.kernel.org Signed-off-by: Sebastian Andrzej Siewior --- 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