Messages in this thread Patch in this message | | | Date | Tue, 7 Apr 2009 19:30:34 GMT | From | Bart Van Assche <> | Subject | [tip:tracing/urgent] branch tracer: Fix for enabling branch profiling makes sparse unusable |
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Commit-ID: d9ad8bc0ca823705413f75b50c442a88cc518b35 Gitweb: http://git.kernel.org/tip/d9ad8bc0ca823705413f75b50c442a88cc518b35 Author: Bart Van Assche <bart.vanassche@gmail.com> AuthorDate: Sun, 5 Apr 2009 16:20:02 +0200 Committer: Ingo Molnar <mingo@elte.hu> CommitDate: Tue, 7 Apr 2009 17:07:40 +0200
branch tracer: Fix for enabling branch profiling makes sparse unusable
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 <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>
--- include/linux/compiler.h | 3 ++- 1 files changed, 2 insertions(+), 1 deletions(-)
diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 6faa7e5..8872ad6 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -76,7 +76,8 @@ 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)
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