| From stable-bounces@linux.kernel.org Tue May 12 13:49:38 2009 |
| From: Bart Van Assche <bart.vanassche@gmail.com> |
| Date: Sat, 9 May 2009 11:43:44 +0200 |
| Subject: Fix for enabling branch profiling makes sparse unusable |
| To: stable@kernel.org |
| Message-ID: <200905091143.44144.bart.vanassche@gmail.com> |
| Content-Disposition: inline |
| |
| From: Bart Van Assche <bart.vanassche@gmail.com> |
| |
| commit d9ad8bc0ca823705413f75b50c442a88cc518b35 upstream. |
| |
| 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. |
| |
| This patch is already included in 2.6.30-rc1 -- see also |
| http://lkml.org/lkml/2009/4/5/120. |
| |
| Signed-off-by: Bart Van Assche <bart.vanassche@gmail.com> |
| Cc: Andrew Morton <akpm@linux-foundation.org> |
| Cc: Steven Rostedt <srostedt@redhat.com> |
| LKML-Reference: <200904051620.02311.bart.vanassche@gmail.com> |
| Signed-off-by: Ingo Molnar <mingo@elte.hu> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> |
| |
| --- |
| include/linux/compiler.h | 3 ++- |
| 1 file changed, 2 insertions(+), 1 deletion(-) |
| |
| --- a/include/linux/compiler.h |
| +++ b/include/linux/compiler.h |
| @@ -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) |
