From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756976Ab0JVOD6 (ORCPT ); Fri, 22 Oct 2010 10:03:58 -0400 Received: from 0122700014.0.fullrate.dk ([95.166.99.235]:60238 "EHLO kernel.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754909Ab0JVODt (ORCPT ); Fri, 22 Oct 2010 10:03:49 -0400 Message-ID: <4CC199D5.1010709@fusionio.com> Date: Fri, 22 Oct 2010 16:04:05 +0200 From: Jens Axboe MIME-Version: 1.0 To: Vivek Goyal CC: linux kernel mailing list , Andi Kleen , Moyer Jeff Moyer Subject: Re: [PATCH] cfq-iosched: Fix a gcc 4.5 warning and put some comments References: <20101021182403.GA8378@redhat.com> <4CC1414B.8070102@fusionio.com> <20101022133101.GA7020@redhat.com> In-Reply-To: <20101022133101.GA7020@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2010-10-22 15:31, Vivek Goyal wrote: > On Fri, Oct 22, 2010 at 09:46:19AM +0200, Jens Axboe wrote: >> On 2010-10-21 20:24, Vivek Goyal wrote: >>> - Andi encountedred following warning with gcc 4.5 >>> >>> linux/block/cfq-iosched.c: In function ‘cfq_dispatch_requests’: >>> linux/block/cfq-iosched.c:2156:3: warning: array subscript is above array >>> bounds >>> >>> - Warning happens due to following code. >>> >>> slice = group_slice * count / >>> max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_prio], >>> cfq_group_busy_queues_wl(cfqd->serving_prio, cfqd, cfqg)); >>> >>> gcc is complaining about cfqg->busy_queues_avg[] being indexed by CFQ >>> prio classes (RT, BE and IDLE) while the array size is only 2. >>> >>> - At run time, we never access cfqg->busy_queues_avg[IDLE] and return from >>> function before this code hits. >>> >>> - To fix warning increase the array size though it will remain unused. This >>> patch also puts some comments to clarify some of the confusions. >>> >>> - I have taken Jens's patch and modified it a bit. >>> >>> - Compile tested with gcc 4.4 and boot tested. I don't have gcc 4.5 >>> running, Andi can you please test it with gcc 4.5 to make sure it >>> worked. >>> >>> Reported-by: Andi Kleen >>> Signed-off-by: Vivek Goyal >>> Signed-off-by: Jens Axboe >> >> Thanks, I'll put this one in. BTW, you can't just add a signed-off-by >> from me (or anyone else, for that matter), they have to be provided >> explicitly by each individual. > > Ok, sorry about that. > > So in general, if I happen to pick somebody's patch, modify it and repost > it, how do I reflect the Signed-off-by of original author. What I usually do is leave the original signed-off-by, then describe my changes, then add my signed-off-by. I think that is acceptable behaviour. It's very different from adding a signed-off-by to something that hasn't been signed-off by the original author yet that's legally an issue. But hey, IANAL :-) -- Jens Axboe