perf: Fix branch stack refcount leak on callchain init failure
On callchain buffers allocation failure, free_event() is called and all the accounting performed in perf_event_alloc() for that event is cancelled. But if the event has branch stack sampling, it is unaccounted as well from the branch stack sampling events refcounts. This is a bug because this accounting is performed after the callchain buffer allocation. As a result, the branch stack sampling events refcount can become negative. To fix this, move the branch stack event accounting before the callchain buffer allocation. Reported-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Stephane Eranian <eranian@google.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1374539466-4799-2-git-send-email-fweisbec@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
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@ -6567,6 +6567,12 @@ done:
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atomic_inc(&nr_comm_events);
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if (event->attr.task)
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atomic_inc(&nr_task_events);
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if (has_branch_stack(event)) {
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static_key_slow_inc(&perf_sched_events.key);
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if (!(event->attach_state & PERF_ATTACH_TASK))
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atomic_inc(&per_cpu(perf_branch_stack_events,
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event->cpu));
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}
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if (event->attr.sample_type & PERF_SAMPLE_CALLCHAIN) {
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err = get_callchain_buffers();
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if (err) {
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@ -6574,12 +6580,6 @@ done:
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return ERR_PTR(err);
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}
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}
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if (has_branch_stack(event)) {
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static_key_slow_inc(&perf_sched_events.key);
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if (!(event->attach_state & PERF_ATTACH_TASK))
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atomic_inc(&per_cpu(perf_branch_stack_events,
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event->cpu));
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}
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}
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return event;
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