Messages in this thread | | | Date | Wed, 8 Apr 2009 19:29:38 +0200 | Subject | Re: [2.6.29] Fix for enabling branch profiling makes sparse unusable | From | Bart Van Assche <> |
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On Sun, Apr 5, 2009 at 4:20 PM, Bart Van Assche <bart.vanassche@gmail.com> 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 <bart.vanassche@gmail.com> > > --- 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/
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