Messages in this thread | | | Date | Wed, 8 Apr 2009 19:58:50 +0200 | From | Ingo Molnar <> | Subject | Re: [2.6.29] Fix for enabling branch profiling makes sparse unusable |
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* Bart Van Assche <bart.vanassche@gmail.com> wrote:
> 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 ?
it already is part of .30-rc1, see d9ad8bc0ca823705413f75b50c442a88cc518b35.
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