From 953c9cddc99983d4bd78936a42c28d5330ccae61 Mon Sep 17 00:00:00 2001 From: Janne Huttunen Date: Mon, 9 Jul 2018 13:59:50 +0300 Subject: [PATCH] perf script python: Fix dict reference counting [ Upstream commit db0ba84c04ef2cf293aaada5ae97531127844d9d ] The dictionaries are attached to the parameter tuple that steals the references and takes care of releasing them when appropriate. The code should not decrement the reference counts explicitly. E.g. if libpython has been built with reference debugging enabled, the superfluous DECREFs will trigger this error when running perf script: Fatal Python error: Objects/tupleobject.c:238 object at 0x7f10f2041b40 has negative ref count -1 Aborted (core dumped) If the reference debugging is not enabled, the superfluous DECREFs might cause the dict objects to be silently released while they are still in use. This may trigger various other assertions or just cause perf crashes and/or weird and unexpected data changes in the stored Python objects. Signed-off-by: Janne Huttunen Acked-by: Jiri Olsa Acked-by: Namhyung Kim Cc: Alexander Shishkin Cc: Andi Kleen Cc: Jaroslav Skarvada Cc: Namhyung Kim Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/1531133990-17485-1-git-send-email-janne.huttunen@nokia.com Signed-off-by: Arnaldo Carvalho de Melo Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- tools/perf/util/scripting-engines/trace-event-python.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) diff --git a/tools/perf/util/scripting-engines/trace-event-python.c b/tools/perf/util/scripting-engines/trace-event-python.c index c7187f067d31..f03fa7a835a1 100644 --- a/tools/perf/util/scripting-engines/trace-event-python.c +++ b/tools/perf/util/scripting-engines/trace-event-python.c @@ -643,14 +643,11 @@ static void python_process_tracepoint(struct perf_sample *sample, if (_PyTuple_Resize(&t, n) == -1) Py_FatalError("error resizing Python tuple"); - if (!dict) { + if (!dict) call_object(handler, t, handler_name); - } else { + else call_object(handler, t, default_handler_name); - Py_DECREF(dict); - } - Py_XDECREF(all_entries_dict); Py_DECREF(t); } @@ -970,7 +967,6 @@ static void python_process_general_event(struct perf_sample *sample, call_object(handler, t, handler_name); - Py_DECREF(dict); Py_DECREF(t); }