From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751494AbcGNQNr (ORCPT ); Thu, 14 Jul 2016 12:13:47 -0400 Received: from smtprelay0031.hostedemail.com ([216.40.44.31]:48136 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751150AbcGNQNo (ORCPT ); Thu, 14 Jul 2016 12:13:44 -0400 X-Session-Marker: 726F737465647440676F6F646D69732E6F7267 X-Spam-Summary: 2,0,0,,d41d8cd98f00b204,rostedt@goodmis.org,:::::::,RULES_HIT:41:355:379:541:599:800:960:973:988:989:1260:1277:1311:1313:1314:1345:1359:1437:1515:1516:1518:1534:1541:1593:1594:1711:1730:1747:1777:1792:2393:2553:2559:2562:2693:3138:3139:3140:3141:3142:3353:3622:3865:3866:3867:3868:3871:3872:3873:3874:4321:5007:6261:7875:10004:10400:10848:10967:11026:11232:11658:11914:12043:12296:12438:12517:12519:12555:12663:12740:13069:13311:13357:13439:14096:14097:14181:14659:14721:21080:21324:30054:30090:30091,0,RBL:none,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fn,MSBL:0,DNSBL:none,Custom_rules:0:0:0,LFtime:3,LUA_SUMMARY:none X-HE-Tag: girls55_77c00c529cd43 X-Filterd-Recvd-Size: 2385 Date: Thu, 14 Jul 2016 12:13:41 -0400 From: Steven Rostedt To: Sebastian Andrzej Siewior Cc: linux-rt-users@vger.kernel.org, linux-kernel@vger.kernel.org, tglx@linutronix.de Subject: Re: [RT PATCH 1/2] timers: wakeup all timer waiters Message-ID: <20160714121341.2b0e70f5@gandalf.local.home> In-Reply-To: <1468512304-15310-1-git-send-email-bigeasy@linutronix.de> References: <1468512304-15310-1-git-send-email-bigeasy@linutronix.de> X-Mailer: Claws Mail 3.13.2 (GTK+ 2.24.30; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 14 Jul 2016 18:05:03 +0200 Sebastian Andrzej Siewior wrote: > The base lock is dropped during the invocation if the timer. That means > it is possible that we have one waiter while timer1 is running and once > this one finished, we get another waiter while timer2 is running. Since > we wake up only one waiter it is possible that we miss the other one. > This will probably heal itself over time because most of the time we > complete timers without an active wake up. > To avoid the scenario where we don't wake up all waiters at once, > wake_up_all() is used. > > Cc: stable-rt@vger.kernel.org > Signed-off-by: Sebastian Andrzej Siewior > --- > kernel/time/timer.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/time/timer.c b/kernel/time/timer.c > index 5f9d3599ef0a..b3c3d3a6216f 100644 > --- a/kernel/time/timer.c > +++ b/kernel/time/timer.c > @@ -1051,7 +1051,7 @@ static void wait_for_running_timer(struct timer_list *timer) > base->running_timer != timer); > } > > -# define wakeup_timer_waiters(b) wake_up(&(b)->wait_for_running_timer) > +# define wakeup_timer_waiters(b) wake_up_all(&(b)->wait_for_running_timer) OK, I just received this patch (way after patch 2) I'm assuming that patch two was done such that you don't do a "wake_up_all" under a spinlock. -- Steve > #else > static inline void wait_for_running_timer(struct timer_list *timer) > {