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perf: Fix errors path in perf_output_begin()

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In case the sampling buffer has no "payload" pages,
nr_pages is 0. The problem is that the error path in
perf_output_begin() skips to a label which assumes
perf_output_lock() has been issued which is not the
case. That triggers a WARN_ON() in
perf_output_unlock().

This patch fixes the problem by skipping
perf_output_unlock() in case data->nr_pages is 0.

Signed-off-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <4bf13674.014fd80a.6c82.ffffb20c@mx.google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Stephane Eranian 2010-05-17 12:46:01 +02:00 committed by Ingo Molnar
parent 4f41c013f5
commit 00d1d0b095
1 changed files with 1 additions and 1 deletions
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2
kernel/perf_event.c
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@ -3036,7 +3036,7 @@ int perf_output_begin(struct perf_output_handle *handle,
handle->sample = sample;
if (!data->nr_pages)
goto fail;
goto out;
have_lost = atomic_read(&data->lost);
if (have_lost)