From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Bergmann Subject: Re: linux-next: build warning after merge of the char-misc tree Date: Fri, 15 Feb 2013 18:07:46 +0000 Message-ID: <201302151807.46217.arnd@arndb.de> References: <20130215162657.6dd03d27e8cfed0c134b5dd3@canb.auug.org.au> <20130215173429.GA27707@kroah.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Return-path: Received: from moutng.kundenserver.de ([212.227.17.8]:50825 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751988Ab3BOSH5 (ORCPT ); Fri, 15 Feb 2013 13:07:57 -0500 In-Reply-To: <20130215173429.GA27707@kroah.com> Sender: linux-next-owner@vger.kernel.org List-ID: To: Greg KH Cc: Stephen Rothwell , linux-next@vger.kernel.org, linux-kernel@vger.kernel.org, David Stevenson On Friday 15 February 2013, Greg KH wrote: > On Fri, Feb 15, 2013 at 04:26:57PM +1100, Stephen Rothwell wrote: > > Hi all, > > > > After merging the char-misc tree, today's linux-next build (x86_64 > > allmodconfig) produced this warning: > > > > drivers/w1/slaves/w1_therm.c: In function 'w1_therm_read': > > drivers/w1/slaves/w1_therm.c:245:15: warning: 'crc' may be used uninitialized in this function [-Wuninitialized] > > > > Its a false positive, but it was introduced by commit 867ff9880d5d > > ("w1_therm: Retries: remove old code add CRC") > > I don't see that here with gcc 4.7.1, perhaps you need to upgrade your > version of gcc to not show these false positives? I see the same warning with gcc-4.6.3, 4.7.2 and 4.8.0-20130114 on ARM. In case of 4.8, the output is drivers/w1/slaves/w1_therm.c: In function 'w1_therm_read': drivers/w1/slaves/w1_therm.c:245:15: warning: 'crc' may be used uninitialized in this function [-Wmaybe-uninitialized] c -= snprintf(buf + PAGE_SIZE - c, c, ": crc=%02x %s\n", ^ I actually see much more of these false positives with 4.7 and 4.8 than I get with 4.6, which is the main reason for me to use 4.6 for my daily builds. I agree that this particular false positive is an especially dumb one and it would be good to not just shut up gcc by initializing it, but I have no other idea what to do with the hundreds of such warnings I get. Arnd