From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnaldo Carvalho de Melo Subject: [PATCH 13/14] perf script python: Fix dict reference counting Date: Wed, 11 Jul 2018 16:43:04 -0400 Message-ID: <20180711204305.12924-14-acme@kernel.org> References: <20180711204305.12924-1-acme@kernel.org> Return-path: In-Reply-To: <20180711204305.12924-1-acme@kernel.org> Sender: linux-kernel-owner@vger.kernel.org To: Ingo Molnar Cc: Clark Williams , linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, Janne Huttunen , Alexander Shishkin , Andi Kleen , Jaroslav Skarvada , Namhyung Kim , Peter Zijlstra , Arnaldo Carvalho de Melo List-Id: linux-perf-users.vger.kernel.org From: Janne Huttunen 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 --- 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 8b2eb6dbff4d..bc32e57d17be 100644 --- a/tools/perf/util/scripting-engines/trace-event-python.c +++ b/tools/perf/util/scripting-engines/trace-event-python.c @@ -908,14 +908,11 @@ 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); } @@ -1235,7 +1232,6 @@ static void python_process_general_event(struct perf_sample *sample, call_object(handler, t, handler_name); - Py_DECREF(dict); Py_DECREF(t); } -- 2.14.4