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From: Jiri Olsa <jolsa@kernel.org>
To: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: lkml <linux-kernel@vger.kernel.org>,
	David Ahern <dsahern@gmail.com>, Ingo Molnar <mingo@kernel.org>,
	Namhyung Kim <namhyung@kernel.org>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>
Subject: [PATCH 04/10] perf python: Fix pyrf_evlist__read_on_cpu event consuming
Date: Sun, 10 Jul 2016 13:07:56 +0200	[thread overview]
Message-ID: <1468148882-10362-5-git-send-email-jolsa@kernel.org> (raw)
In-Reply-To: <1468148882-10362-1-git-send-email-jolsa@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 <jolsa@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

  parent reply	other threads:[~2016-07-10 11:09 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-07-10 11:07 [PATCH 00/10] perf python: Add support to access tracepoint fields Jiri Olsa
2016-07-10 11:07 ` [PATCH 01/10] perf tools: Make perf_evlist__event2evsel public Jiri Olsa
2016-07-13  7:24   ` [tip:perf/core] perf evlist: Make event2evsel public tip-bot for Jiri Olsa
2016-07-10 11:07 ` [PATCH 02/10] perf tools: Introduce trace_event__tp_format_id function Jiri Olsa
2016-07-13  7:25   ` [tip:perf/core] perf tools: Introduce trace_event__tp_format_id() tip-bot for Jiri Olsa
2016-07-10 11:07 ` [PATCH 03/10] perf python: Init perf_event_attr::size in perf.evsel constructor Jiri Olsa
2016-07-13  7:25   ` [tip:perf/core] " tip-bot for Jiri Olsa
2016-07-10 11:07 ` Jiri Olsa [this message]
2016-07-13  7:26   ` [tip:perf/core] perf python: Fix pyrf_evlist__read_on_cpu event consuming tip-bot for Jiri Olsa
2016-07-10 11:07 ` [PATCH 05/10] perf python: Put perf.event objects into dictionary Jiri Olsa
2016-07-13  7:26   ` [tip:perf/core] " tip-bot for Jiri Olsa
2016-07-10 11:07 ` [PATCH 06/10] perf python: Add perf.tracepoint method Jiri Olsa
2016-07-13  7:27   ` [tip:perf/core] " tip-bot for Jiri Olsa
2016-07-10 11:07 ` [PATCH 07/10] perf python: Add struct evsel into struct pyrf_event Jiri Olsa
2016-07-13  7:27   ` [tip:perf/core] " tip-bot for Jiri Olsa
2016-07-10 11:08 ` [PATCH 08/10] perf python: Add support to resolve tracepoint fields Jiri Olsa
2016-07-13  7:27   ` [tip:perf/core] " tip-bot for Jiri Olsa
2016-07-10 11:08 ` [PATCH 09/10] perf python: Add tracepoint example Jiri Olsa
2016-07-13  7:28   ` [tip:perf/core] " tip-bot for Jiri Olsa
2016-07-10 11:08 ` [PATCH 10/10] perf script python: Fix string vs byte array resolving Jiri Olsa
2016-07-11 15:54   ` Steven Rostedt
2016-07-12  8:11     ` Jiri Olsa
2016-07-12 12:37       ` Steven Rostedt
2016-07-12 12:52         ` Jiri Olsa
2016-07-12 13:00           ` Steven Rostedt
2016-07-12 13:35             ` Jiri Olsa
2016-07-12 13:48               ` Steven Rostedt
2016-07-12 19:27                 ` Arnaldo Carvalho de Melo
2016-07-12 19:48                   ` Steven Rostedt
2016-07-13  9:06                     ` Jiri Olsa

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