From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752613Ab1GYXt7 (ORCPT ); Mon, 25 Jul 2011 19:49:59 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.125]:39268 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751794Ab1GYXty (ORCPT ); Mon, 25 Jul 2011 19:49:54 -0400 X-Authority-Analysis: v=1.1 cv=sbbt6Wn8j+VvNVI1Ftt/uHhinWyuFt+R57MN9Ty2Tys= c=1 sm=0 a=wp_X8QvuP7UA:10 a=5SG0PmZfjMsA:10 a=Q9fys5e9bTEA:10 a=OPBmh+XkhLl+Enan7BmTLg==:17 a=meVymXHHAAAA:8 a=20KFwNOVAAAA:8 a=YMhppL7k-yvyJFBL_mUA:9 a=HP0wG5ovJNupJBSRVpgA:7 a=PUjeQqilurYA:10 a=jeBq3FmKZ4MA:10 a=OPBmh+XkhLl+Enan7BmTLg==:117 X-Cloudmark-Score: 0 X-Originating-IP: 67.242.120.143 Subject: Re: [PATCH] TRACING: Fix a copmile warning From: Steven Rostedt To: Arnaud Lacombe Cc: stufever@gmail.com, linux-kernel@vger.kernel.org, Wang Shaoyan , Frederic Weisbecker , Ingo Molnar In-Reply-To: References: <1310982010-13849-1-git-send-email-wangshaoyan.pt@taobao.com> <1311618747.3526.32.camel@gandalf.stny.rr.com> <1311625197.3526.35.camel@gandalf.stny.rr.com> Content-Type: text/plain; charset="ISO-8859-15" Date: Mon, 25 Jul 2011 19:49:48 -0400 Message-ID: <1311637788.3526.38.camel@gandalf.stny.rr.com> Mime-Version: 1.0 X-Mailer: Evolution 2.32.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2011-07-25 at 18:38 -0400, Arnaud Lacombe wrote: > Hi, > > On Mon, Jul 25, 2011 at 4:19 PM, Steven Rostedt wrote: > > On Mon, 2011-07-25 at 15:43 -0400, Arnaud Lacombe wrote: > > > >> Actually, we have a special uninitialized_var(x) macro to handle such > >> false positive. From include/linux/compiler-gcc.h: > >> > >> /* > >> * A trick to suppress uninitialized variable warning without generating any > >> * code > >> */ > >> #define uninitialized_var(x) x = x > > > > I'm aware of that too, but I think that is inappropriate as well. As I > > said, some versions of gcc report it, others don't. Seems that gcc 4.6.0 > > says this is an error where 4.5.1 does not (I just tried both). > > > did you ? gcc 4.5.1 from Fedora 14 definitively shows the warning: Heh, I didn't use Fedora's version. I wonder if they added a patch or built it differently. I built my own 4.5.1 as well as my own 4.6.0. -- Steve > > # make ARCH=i386 kernel/trace/trace_printk.o V=1 > [...] > gcc -Wp,-MD,kernel/trace/.trace_printk.o.d -nostdinc -isystem > /usr/lib/gcc/x86_64-redhat-linux/4.5.1/include [...] -c -o > kernel/trace/trace_printk.o kernel/trace/trace_printk.c > /src/linux/linux/kernel/trace/trace_printk.c: In function > 'hold_module_trace_bprintk_format': > /src/linux/linux/kernel/trace/trace_printk.c:52:8: warning: 'fmt' may > be used uninitialized in this function > > # gcc -v > gcc -v > Using built-in specs. > COLLECT_GCC=gcc > COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-redhat-linux/4.5.1/lto-wrapper > Target: x86_64-redhat-linux > Configured with: ../configure --prefix=/usr --mandir=/usr/share/man > --infodir=/usr/share/info > --with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-bootstrap > --enable-shared --enable-threads=posix --enable-checking=release > --with-system-zlib --enable-__cxa_atexit > --disable-libunwind-exceptions --enable-gnu-unique-object > --enable-linker-build-id > --enable-languages=c,c++,objc,obj-c++,java,fortran,ada,lto > --enable-plugin --enable-java-awt=gtk --disable-dssi > --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-1.5.0.0/jre > --enable-libgcj-multifile --enable-java-maintainer-mode > --with-ecj-jar=/usr/share/java/eclipse-ecj.jar > --disable-libjava-multilib --with-ppl --with-cloog --with-tune=generic > --with-arch_32=i686 --build=x86_64-redhat-linux > Thread model: posix > gcc version 4.5.1 20100924 (Red Hat 4.5.1-4) (GCC) > > - Arnaud