Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753523AbYLTKx6 (ORCPT ); Sat, 20 Dec 2008 05:53:58 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751971AbYLTKxt (ORCPT ); Sat, 20 Dec 2008 05:53:49 -0500 Received: from e28smtp05.in.ibm.com ([59.145.155.5]:41450 "EHLO e28smtp05.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751555AbYLTKxt (ORCPT ); Sat, 20 Dec 2008 05:53:49 -0500 Date: Sat, 20 Dec 2008 16:26:52 +0530 From: Vaidyanathan Srinivasan To: Andrew Morton Cc: linux-kernel@vger.kernel.org, suresh.b.siddha@intel.com, venkatesh.pallipadi@intel.com, a.p.zijlstra@chello.nl, mingo@elte.hu, dipankar@in.ibm.com, balbir@linux.vnet.ibm.com, vatsa@linux.vnet.ibm.com, ego@in.ibm.com, andi@firstfloor.org, davecb@sun.com, tconnors@astro.swin.edu.au, maxk@qualcomm.com, gregory.haskins@gmail.com, pavel@suse.cz, Rusty Russell Subject: Re: [PATCH v7 4/8] sched: nominate preferred wakeup cpu Message-ID: <20081220105652.GD24181@dirshya.in.ibm.com> Reply-To: svaidy@linux.vnet.ibm.com References: <20081218175313.29812.4781.stgit@drishya.in.ibm.com> <20081218175622.29812.69201.stgit@drishya.in.ibm.com> <20081219135508.9c6217ba.akpm@linux-foundation.org> <20081220043638.GA24181@dirshya.in.ibm.com> <20081219204455.5f954823.akpm@linux-foundation.org> <20081220100228.GB24181@dirshya.in.ibm.com> <20081220103602.GC24181@dirshya.in.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20081220103602.GC24181@dirshya.in.ibm.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2082 Lines: 55 * Vaidyanathan Srinivasan [2008-12-20 16:06:02]: > * Vaidyanathan Srinivasan [2008-12-20 15:32:28]: > > > * Andrew Morton [2008-12-19 20:44:55]: > > > > > On Sat, 20 Dec 2008 10:06:38 +0530 Vaidyanathan Srinivasan wrote: > > > > > > > > > > > > > kernel/sched.c: In function 'schedule': > > > > > kernel/sched.c:3679: warning: 'active_balance' may be used uninitialized in this function > > > > > > > > > > This warning is correct - the code is buggy. > > > > > > > > Yes this is my code bug. I did not see the warning in sched.c. Is > > > > there any build option that I need to pass in order to get -Wall > > > > effect? > > > > > > That was just with plain old kbuild: `make allmodconfig;make'. > > > > > > That warning was produced by gcc-4.0.2. If you're using something more > > > recent then gcc has regressed. > > > > This is an interesting problem. I am unable to get that warning in the > > following GCC versions even with a combination of the following > > cmdline options: -Wall -Wextra -Wuninitialized > > > > gcc version 4.1.2 20070502 > > gcc version 4.2.3 > > > > I will look for older gcc and check this out. > > I am able to get the above warning in > gcc version 3.4.6 (Debian 3.4.6-9) > with default kbuild, no additional params. > > Did not get the warning in > gcc version 4.1.3 20080623 > > Hence there has been some change in GCC that prevented the > uninitialized warning. Related GCC bug: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=179 Claimed to have been fixed in GCC 4.4, but I don't know if we are ready to test kernel compile with GCC 4.4. I have tested till gcc version 4.3.2 (Debian 4.3.2-1) and the bug is not fixed. I do not get the warning from sched.c. --Vaidy -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/