Commit-ID: fc3b86d673e41ac66b4ba5b75a90c2fcafb90089 Gitweb: http://git.kernel.org/tip/fc3b86d673e41ac66b4ba5b75a90c2fcafb90089 Author: Frederic Weisbecker <[email protected]> AuthorDate: Fri, 2 Aug 2013 18:29:54 +0200 Committer: Ingo Molnar <[email protected]> CommitDate: Fri, 16 Aug 2013 17:55:50 +0200
perf: Roll back callchain buffer refcount under the callchain mutex When we fail to allocate the callchain buffers, we roll back the refcount we did and return from get_callchain_buffers(). However we take the refcount and allocate under the callchain lock but the rollback is done outside the lock. As a result, while we roll back, some concurrent callchain user may call get_callchain_buffers(), see the non-zero refcount and give up because the buffers are NULL without itself retrying the allocation. The consequences aren't that bad but that behaviour looks weird enough and it's better to give their chances to the following callchain users where we failed. Reported-by: Jiri Olsa <[email protected]> Signed-off-by: Frederic Weisbecker <[email protected]> Acked-by: Jiri Olsa <[email protected]> Cc: Namhyung Kim <[email protected]> Cc: Arnaldo Carvalho de Melo <[email protected]> Cc: Stephane Eranian <[email protected]> Signed-off-by: Peter Zijlstra <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]> --- kernel/events/callchain.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/kernel/events/callchain.c b/kernel/events/callchain.c index 76a8bc5..97b67df 100644 --- a/kernel/events/callchain.c +++ b/kernel/events/callchain.c @@ -116,10 +116,11 @@ int get_callchain_buffers(void) err = alloc_callchain_buffers(); exit: - mutex_unlock(&callchain_mutex); if (err) atomic_dec(&nr_callchain_events); + mutex_unlock(&callchain_mutex); + return err; } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
