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.
Link: http://lkml.kernel.org/n/tip-8dbalvrufeisa4cioyd9k...@git.kernel.org Signed-off-by: Jiri Olsa <jo...@kernel.org> --- tools/perf/util/python.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/tools/perf/util/python.c b/tools/perf/util/python.c index d0c1267741ee..c68ef0319114 100644 --- a/tools/perf/util/python.c +++ b/tools/perf/util/python.c @@ -865,12 +865,14 @@ static PyObject *pyrf_evlist__read_on_cpu(struct pyrf_evlist *pevlist, PyObject *pyevent = pyrf_event__new(event); struct pyrf_event *pevent = (struct pyrf_event *)pyevent; - perf_evlist__mmap_consume(evlist, cpu); - if (pyevent == NULL) return PyErr_NoMemory(); 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) return PyErr_Format(PyExc_OSError, "perf: can't parse sample, err=%d", err); -- 2.4.11
