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perf python: Fix pyrf_evlist__read_on_cpu event consuming 

We can't consume the event before parsing it. Under heavy load we could
get caught by kernel writer overwriting the event we're trying to parse.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1468148882-10362-5-git-send-email-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Jiri Olsa 2016-07-10 13:07:56 +02:00 committed by Arnaldo Carvalho de Melo
parent ad4e3c0458
commit e8968e6541
1 changed files with 4 additions and 2 deletions
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6
tools/perf/util/python.c
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@ -865,12 +865,14 @@ static PyObject *pyrf_evlist__read_on_cpu(struct pyrf_evlist *pevlist,
PyObject *pyevent = pyrf_event__new(event); PyObject *pyevent = pyrf_event__new(event);
struct pyrf_event *pevent = (struct pyrf_event *)pyevent; struct pyrf_event *pevent = (struct pyrf_event *)pyevent;
perf_evlist__mmap_consume(evlist, cpu);
if (pyevent == NULL) if (pyevent == NULL)
return PyErr_NoMemory(); return PyErr_NoMemory();
err = perf_evlist__parse_sample(evlist, event, &pevent->sample); err = perf_evlist__parse_sample(evlist, event, &pevent->sample);
/* Consume the even only after we parsed it out. */
perf_evlist__mmap_consume(evlist, cpu);
if (err) if (err)
return PyErr_Format(PyExc_OSError, return PyErr_Format(PyExc_OSError,
"perf: can't parse sample, err=%d", err); "perf: can't parse sample, err=%d", err);