4.17-stable review patch. If anyone has any objections, please let me know.
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From: Janne Huttunen janne.huttunen@nokia.com
[ 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 janne.huttunen@nokia.com Acked-by: Jiri Olsa jolsa@kernel.org Acked-by: Namhyung Kim namhyung@kernel.org Cc: Alexander Shishkin alexander.shishkin@linux.intel.com Cc: Andi Kleen ak@linux.intel.com Cc: Jaroslav Skarvada jskarvad@redhat.com Cc: Namhyung Kim namhyung@kernel.org Cc: Peter Zijlstra peterz@infradead.org Link: http://lkml.kernel.org/r/1531133990-17485-1-git-send-email-janne.huttunen@no... Signed-off-by: Arnaldo Carvalho de Melo acme@redhat.com Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- tools/perf/util/scripting-engines/trace-event-python.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-)
--- a/tools/perf/util/scripting-engines/trace-event-python.c +++ b/tools/perf/util/scripting-engines/trace-event-python.c @@ -676,14 +676,11 @@ static void python_process_tracepoint(st 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); }
@@ -1003,7 +1000,6 @@ static void python_process_general_event
call_object(handler, t, handler_name);
- Py_DECREF(dict); Py_DECREF(t); }