From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754627Ab0JVHqG (ORCPT ); Fri, 22 Oct 2010 03:46:06 -0400 Received: from 0122700014.0.fullrate.dk ([95.166.99.235]:39649 "EHLO kernel.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753320Ab0JVHqE (ORCPT ); Fri, 22 Oct 2010 03:46:04 -0400 Message-ID: <4CC1414B.8070102@fusionio.com> Date: Fri, 22 Oct 2010 09:46:19 +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> In-Reply-To: <20101021182403.GA8378@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 2010-10-21 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. -- Jens Axboe