Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934607AbZDHR3w (ORCPT ); Wed, 8 Apr 2009 13:29:52 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753100AbZDHR3l (ORCPT ); Wed, 8 Apr 2009 13:29:41 -0400 Received: from mail-bw0-f169.google.com ([209.85.218.169]:34315 "EHLO mail-bw0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751718AbZDHR3k convert rfc822-to-8bit (ORCPT ); Wed, 8 Apr 2009 13:29:40 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=gilsEye0bo8K5AAX6VGiDpmJMOSew9kJSbF1gnqx822crF5lbDNRc6XVJO90lMUzrs HBhmriE57bGsm2/0znqH/Cc1vdq2K6Sa8pj77NaCzT6Gy3vRpKUcO2TWr26F29LEJJCR ScAM/cU8+c8LkKgn8wcCN4fTOvVsp++fv9bgk= MIME-Version: 1.0 In-Reply-To: <200904051620.02311.bart.vanassche@gmail.com> References: <200904051620.02311.bart.vanassche@gmail.com> Date: Wed, 8 Apr 2009 19:29:38 +0200 Message-ID: Subject: Re: [2.6.29] Fix for enabling branch profiling makes sparse unusable From: Bart Van Assche To: Steven Rostedt , Ingo Molnar Cc: Andrew Morton , LKML Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2114 Lines: 51 On Sun, Apr 5, 2009 at 4:20 PM, Bart Van Assche wrote: > One of the changes between kernels 2.6.28 and 2.6.29 is that a branch profiler > has been added for if() statements. Unfortunately this patch makes the sparse > output unusable with CONFIG_TRACE_BRANCH_PROFILING=y: when branch profiling is > enabled, sparse prints so much false positives that the real issues are no > longer visible. This behavior can be reproduced as follows: > * enable CONFIG_TRACE_BRANCH_PROFILING, e.g. by running make allyesconfig or > ?make allmodconfig. > * run make C=2 > > Result: a huge number of the following sparse warnings. > ... > include/linux/cpumask.h:547:2: warning: symbol '______r' shadows an earlier one > include/linux/cpumask.h:547:2: originally declared here > ... > > The patch below fixes this by disabling branch profiling while analyzing the > kernel code with sparse. > > See also: > * http://lkml.org/lkml/2008/11/21/18 > * http://bugzilla.kernel.org/show_bug.cgi?id=12925 > > Signed-off-by: Bart Van Assche > > --- orig/linux-2.6.29/include/linux/compiler.h ?2009-03-23 19:12:14.000000000 -0400 > +++ linux-2.6.29/include/linux/compiler.h ? ? ? 2009-03-24 08:46:46.000000000 -0400 > @@ -75,7 +75,8 @@ struct ftrace_branch_data { > ?* Note: DISABLE_BRANCH_PROFILING can be used by special lowlevel code > ?* to disable branch tracing on a per file basis. > ?*/ > -#if defined(CONFIG_TRACE_BRANCH_PROFILING) && !defined(DISABLE_BRANCH_PROFILING) > +#if defined(CONFIG_TRACE_BRANCH_PROFILING) \ > + ? ?&& !defined(DISABLE_BRANCH_PROFILING) && !defined(__CHECKER__) > ?void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect); > > ?#define likely_notrace(x) ? ? ?__builtin_expect(!!(x), 1) (ping) Hello, Is there any chance the above patch will get included in the 2.6.30 kernel ? Bart. -- 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/