From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933502AbcGJLJs (ORCPT ); Sun, 10 Jul 2016 07:09:48 -0400 Received: from mx1.redhat.com ([209.132.183.28]:56601 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757126AbcGJLIM (ORCPT ); Sun, 10 Jul 2016 07:08:12 -0400 From: Jiri Olsa To: Arnaldo Carvalho de Melo Cc: lkml , David Ahern , Ingo Molnar , Namhyung Kim , Peter Zijlstra Subject: [PATCH 04/10] perf python: Fix pyrf_evlist__read_on_cpu event consuming Date: Sun, 10 Jul 2016 13:07:56 +0200 Message-Id: <1468148882-10362-5-git-send-email-jolsa@kernel.org> In-Reply-To: <1468148882-10362-1-git-send-email-jolsa@kernel.org> References: <1468148882-10362-1-git-send-email-jolsa@kernel.org> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.30]); Sun, 10 Jul 2016 11:08:12 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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-8dbalvrufeisa4cioyd9k65i@git.kernel.org Signed-off-by: Jiri Olsa --- 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