From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752449AbbDOTRD (ORCPT ); Wed, 15 Apr 2015 15:17:03 -0400 Received: from smtprelay0024.hostedemail.com ([216.40.44.24]:42736 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751480AbbDOTQz (ORCPT ); Wed, 15 Apr 2015 15:16:55 -0400 X-Session-Marker: 726F737465647440676F6F646D69732E6F7267 X-Spam-Summary: 2,0,0,,d41d8cd98f00b204,rostedt@goodmis.org,:::::::::::::::::::::::::::::::::::::,RULES_HIT:41:355:379:541:599:800:960:973:988:989:1260:1277:1311:1313:1314:1345:1359:1437:1515:1516:1518:1534:1538:1593:1594:1711:1730:1747:1777:1792:2393:2553:2559:2562:3138:3139:3140:3141:3142:3352:3622:3865:3866:3867:3868:3870:3871:3872:3874:5007:6261:6742:7875:10004:10400:10848:10967:11232:11658:11914:12296:12517:12519:12740:13069:13149:13230:13311:13357:21080,0,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 X-HE-Tag: order89_3c06c7041615d X-Filterd-Recvd-Size: 2334 Date: Wed, 15 Apr 2015 15:16:51 -0400 From: Steven Rostedt To: Jason Low Cc: Ingo Molnar , Peter Zijlstra , Mel Gorman , Rik van Riel , Linus Torvalds , Peter Zijlstra , Thomas Gleixner , linux-kernel@vger.kernel.org, "Paul E. McKenney" , Andrew Morton , Oleg Nesterov , Mike Galbraith , Frederic Weisbecker , Mel Gorman , Preeti U Murthy , hideaki.kimura@hp.com, Aswin Chandramouleeswaran , Scott J Norton Subject: Re: [PATCH 1/3] sched, timer: Remove usages of ACCESS_ONCE in the scheduler Message-ID: <20150415151651.312c8f48@gandalf.local.home> In-Reply-To: <1429123749.7039.107.camel@j-VirtualBox> References: <1429052986-9420-1-git-send-email-jason.low2@hp.com> <1429052986-9420-2-git-send-email-jason.low2@hp.com> <20150414195906.3adc89d9@gandalf.local.home> <1429063953.7039.88.camel@j-VirtualBox> <20150414224059.061ec5bf@grimm.local.home> <20150415074601.GC13449@gmail.com> <1429123749.7039.107.camel@j-VirtualBox> X-Mailer: Claws Mail 3.11.1 (GTK+ 2.24.25; 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 Wed, 15 Apr 2015 11:49:09 -0700 Jason Low wrote: > So I'll keep the READ_ONCE nested inside WRITE_ONCE for the purpose of > this patch since this patch is a conversion from ACCESS_ONCE, but yes, > if the original purpose of ACCESS_ONCE was to do an atomic increment, > then the ACCESS_ONCE doesn't help with that. For the purpose of this patch, I think it's fine, as being more paranoid is better than not being paranoid enough. But this has shined light onto whether it is needed or not, and we should figure that out in the not so far future. -- Steve