linux-kernel - [PATCH 4.19 223/313] perf python: Do not force closing original perf descriptor in evlist.get

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Date:   Mon, 11 Feb 2019 15:18:23 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Ondřej Lysoněk <olysonek@...hat.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jaroslav Škarvada <jskarvad@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Arnaldo Carvalho de Melo <acme@...hat.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.19 223/313] perf python: Do not force closing original perf descriptor in evlist.get_pollfd()

4.19-stable review patch.  If anyone has any objections, please let me know.

------------------

[ Upstream commit a389aece97938966616ce0336466b98b0351ef10 ]

Ondřej reported that when compiled with python3, the python extension
regresses in evlist.get_pollfd function behaviour.

The evlist.get_pollfd function creates file objects from evlist's fds
and returns them in a list. The python3 version also sets them to 'close
the original descriptor' when the object dies (is closed), by passing
True via the 'closefd' arg in the PyFile_FromFd call.

The python's closefd doc says:

  If closefd is False, the underlying file descriptor will be kept open
  when the file is closed.

That's why the following line in python3 closes all evlist fds:

  evlist.get_pollfd()

the returned list is immediately destroyed and that takes down the
original events fds.

Passing closefd as False to PyFile_FromFd to fix this.

Reported-by: Ondřej Lysoněk <olysonek@...hat.com>
Signed-off-by: Jiri Olsa <jolsa@...nel.org>
Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: Jaroslav Škarvada <jskarvad@...hat.com>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Fixes: 66dfdff03d19 ("perf tools: Add Python 3 support")
Link: http://lkml.kernel.org/r/20181226112121.5285-1-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 tools/perf/util/python.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/python.c b/tools/perf/util/python.c
index ce501ba14b08..69f5f6142dcf 100644
--- a/tools/perf/util/python.c
+++ b/tools/perf/util/python.c
@@ -939,7 +939,8 @@ static PyObject *pyrf_evlist__get_pollfd(struct pyrf_evlist *pevlist,
 
 		file = PyFile_FromFile(fp, "perf", "r", NULL);
 #else
-		file = PyFile_FromFd(evlist->pollfd.entries[i].fd, "perf", "r", -1, NULL, NULL, NULL, 1);
+		file = PyFile_FromFd(evlist->pollfd.entries[i].fd, "perf", "r", -1,
+				     NULL, NULL, NULL, 0);
 #endif
 		if (file == NULL)
 			goto free_list;
-- 
2.19.1