From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753176AbcJCQYC (ORCPT ); Mon, 3 Oct 2016 12:24:02 -0400 Received: from smtprelay0114.hostedemail.com ([216.40.44.114]:34683 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751687AbcJCQXy (ORCPT ); Mon, 3 Oct 2016 12:23:54 -0400 X-Session-Marker: 726F737465647440676F6F646D69732E6F7267 X-Spam-Summary: 2,0,0,,d41d8cd98f00b204,rostedt@goodmis.org,:::::::::::::::::::,RULES_HIT:41:355:379:541:599:800:960:973:988:989:1260:1277:1311:1313:1314:1345:1359:1437:1515:1516:1518:1534:1539:1593:1594:1711:1730:1747:1777:1792:2393:2553:2559:2562:2691:2895:3138:3139:3140:3141:3142:3352:3622:3865:3868:3870:3871:3872:3874:5007:6261:7875:10004:10400:10848:10967:11026:11232:11473:11658:11914:12043:12663:12740:12760:13069:13311:13357:13439:14181:14659:14721:21080:21324:30054:30070:30090:30091,0,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:2,LUA_SUMMARY:none X-HE-Tag: game45_78f4e5d8a435e X-Filterd-Recvd-Size: 1804 Date: Mon, 3 Oct 2016 12:23:49 -0400 From: Steven Rostedt To: Peter Zijlstra Cc: mingo@kernel.org, tglx@linutronix.de, juri.lelli@arm.com, xlpang@redhat.com, bigeasy@linutronix.de, linux-kernel@vger.kernel.org, mathieu.desnoyers@efficios.com, jdesfossez@efficios.com, bristot@redhat.com Subject: Re: [RFC][PATCH 4/4] futex: Rewrite FUTEX_UNLOCK_PI Message-ID: <20161003122349.620df91e@gandalf.local.home> In-Reply-To: <20161003154514.GF3117@twins.programming.kicks-ass.net> References: <20161003091234.879763059@infradead.org> <20161003091847.704255067@infradead.org> <20161003113624.04f1f9f2@gandalf.local.home> <20161003154514.GF3117@twins.programming.kicks-ass.net> 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 Mon, 3 Oct 2016 17:45:14 +0200 Peter Zijlstra wrote: > On Mon, Oct 03, 2016 at 11:36:24AM -0400, Steven Rostedt wrote: > > > > + WARN_ON_ONCE(!atomic_inc_not_zero(&pi_state->refcount)); > > > > Don't we have a rule where WARN_ON() and BUG_ON() should never have > > "side effects"? That is, they should only check values, but their > > contents should not update values. > > not that I'm aware, there's various places in the kernel (including > kref.h) that relies on WARN_ON*() having side effects. Looking more into it, I believe the "no side effect" is only with BUG_ON(), as WARN_ON() can be used within if statements. -- Steve