[tip:perf/core] perf python: Reference Py_None before returning it

[tip-bot for Petr Machata]

Commit-ID:  83428f2fad48e16fddff0cb445cb4fedf5afe4ab
Gitweb:     https://git.kernel.org/tip/83428f2fad48e16fddff0cb445cb4fedf5afe4ab
Author:     Petr Machata <petrm@xxxxxxxxxxxx>
AuthorDate: Thu, 22 Mar 2018 00:57:32 +0100
Committer:  Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Fri, 23 Mar 2018 16:45:20 -0300

perf python: Reference Py_None before returning it

Python None objects are handled just like all the other objects with
respect to their reference counting. Before returning Py_None, its
reference count thus needs to be bumped.

Signed-off-by: Petr Machata <petrm@xxxxxxxxxxxx>
Acked-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Petr Machata <petrm@xxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/b1e565ecccf68064d8d54f37db5d028dda8fa522.1521675563.git.petrm@xxxxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 tools/perf/util/python.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/python.c b/tools/perf/util/python.c
index b956868fd445..863b61478edd 100644
--- a/tools/perf/util/python.c
+++ b/tools/perf/util/python.c
@@ -1004,8 +1004,10 @@ static PyObject *pyrf_evlist__read_on_cpu(struct pyrf_evlist *pevlist,
 			return PyErr_NoMemory();
 
 		evsel = perf_evlist__event2evsel(evlist, event);
-		if (!evsel)
+		if (!evsel) {
+			Py_INCREF(Py_None);
 			return Py_None;
+		}
 
 		pevent->evsel = evsel;