From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752023AbcGNRTv (ORCPT ); Thu, 14 Jul 2016 13:19:51 -0400 Received: from smtprelay0053.hostedemail.com ([216.40.44.53]:49246 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751535AbcGNRTt (ORCPT ); Thu, 14 Jul 2016 13:19:49 -0400 X-Session-Marker: 726F737465647440676F6F646D69732E6F7267 X-Spam-Summary: 2,0,0,,d41d8cd98f00b204,rostedt@goodmis.org,:::::::,RULES_HIT:41:355:379:541:599:800:960:988:989:1260:1277:1311:1313:1314:1345:1359:1437:1515:1516:1518:1534:1541:1593:1594:1711:1730:1747:1777:1792:2393:2553:2559:2562:3138:3139:3140:3141:3142:3352:3622:3865:3866:3867:3868:3870:3871:3872:3873:3874:4321:5007:6261:7875:7903:8700:10004:10400:10848:10967:11026:11232:11658:11914:12043:12438:12517:12519:12663:12740:13069:13311:13357:13439:14096:14097:14181:14659:21067:21080:21324:30012:30054:30056:30090:30091,0,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:18,LUA_SUMMARY:none X-HE-Tag: dress53_727c1d0190f37 X-Filterd-Recvd-Size: 2064 Date: Thu, 14 Jul 2016 13:19:45 -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: <20160714131945.67cc8ce5@gandalf.local.home> In-Reply-To: References: <1468512304-15310-1-git-send-email-bigeasy@linutronix.de> <20160714121341.2b0e70f5@gandalf.local.home> 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 19:14:58 +0200 Sebastian Andrzej Siewior wrote: > On 07/14/2016 06:13 PM, Steven Rostedt wrote: > >> > >> -# 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. > > No. I pulled in new timer code in and had to redo this part of RT. > > While doing so I noticed that we drop the base lock during timer > invocations and so it could be possible that we have two invocations > of del_timer_sync() on a timer on the same "base" (one after the > other). This is patch #1. > > After that I saw that we do the wake up under the base lock but there > is no reason for it. So here is patch #2. > > Patch #1 is something that could happen in theory and I did not run in > any problem. > OK, so patch 2 was just discovered by reviewing code? -- Steve