From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756129Ab2CLR0r (ORCPT ); Mon, 12 Mar 2012 13:26:47 -0400 Received: from merlin.infradead.org ([205.233.59.134]:54564 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755036Ab2CLR0q convert rfc822-to-8bit (ORCPT ); Mon, 12 Mar 2012 13:26:46 -0400 Message-ID: <1331374349.18960.15.camel@twins> Subject: Re: [RFC PATCH 5/6] implement per-cpu&per-domain state machine call_srcu() From: Peter Zijlstra To: paulmck@linux.vnet.ibm.com Cc: Lai Jiangshan , Lai Jiangshan , linux-kernel@vger.kernel.org, mingo@elte.hu, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@polymtl.ca, josh@joshtriplett.org, niv@us.ibm.com, tglx@linutronix.de, rostedt@goodmis.org, Valdis.Kletnieks@vt.edu, dhowells@redhat.com, eric.dumazet@gmail.com, darren@dvhart.com, fweisbec@gmail.com, patches@linaro.org Date: Sat, 10 Mar 2012 11:12:29 +0100 In-Reply-To: <20120308194905.GB2412@linux.vnet.ibm.com> References: <1331023359-6987-1-git-send-email-laijs@cn.fujitsu.com> <1331027858-7648-1-git-send-email-laijs@cn.fujitsu.com> <1331027858-7648-5-git-send-email-laijs@cn.fujitsu.com> <1331031498.11248.273.camel@twins> <1331048298.11248.320.camel@twins> <20120308194905.GB2412@linux.vnet.ibm.com> Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT X-Mailer: Evolution 3.2.2- Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2012-03-08 at 11:49 -0800, Paul E. McKenney wrote: > > I too have used (long)(a - b) for a long time, but I saw with my own eyes > the glee in the compiler-writers' eyes when they discussed signed overflow > being undefined in the C standard. I believe that the reasons for signed > overflow being undefined are long obsolete, but better safe than sorry. Thing is, if they break that the whole kernel comes falling down, I really wouldn't worry about RCU at that point. But to each their pet-paranoia I guess ;-)