linux-kernel - [PATCH 1/3] Add missing calls to Py

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Date:	Wed, 04 Jun 2014 14:07:10 +0200
From:	Joseph Schuchart <joseph.schuchart@...dresden.de>
To:	Namhyung Kim <namhyung@...il.com>
CC:	Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Paul Mackerras <paulus@...ba.org>,
	Ingo Molnar <mingo@...hat.com>,
	Thomas Ilsche <thomas.ilsche@...dresden.de>,
	linux-kernel@...r.kernel.org
Subject: [PATCH 1/3] Add missing calls to Py_DECREF

Add missing calls to Py_DECREF.

The function PyObject_CallObject() returns a new PyObject reference 
on which Py_DECREF has to be called to avoid memory leaks.
This patch adds these calls where necessary.

It also marks handler_call_die() as NORETURN to make this clear and to 
avoid unnecessary else statements. Note that the abort() is necessary 
since Py_FatalError() does not return but seems to be missing the 
__noretun__ attribute in Python versions <=2.7

Signed-off-by: Joseph Schuchart <joseph.schuchart@...dresden.de>

---
 tools/perf/util/scripting-engines/trace-event-python.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/scripting-engines/trace-event-python.c b/tools/perf/util/scripting-engines/trace-event-python.c
index cd9774d..8454dc9 100644
--- a/tools/perf/util/scripting-engines/trace-event-python.c
+++ b/tools/perf/util/scripting-engines/trace-event-python.c
@@ -50,10 +50,14 @@ static int zero_flag_atom;
 
 static PyObject *main_module, *main_dict;
 
+static void handler_call_die(const char *handler_name) NORETURN;
 static void handler_call_die(const char *handler_name)
 {
 	PyErr_Print();
 	Py_FatalError("problem in Python trace event handler");
+	// Py_FatalError does not return
+	// but we have to make the compiler happy
+	abort();
 }
 
 /*
@@ -97,6 +101,7 @@ static void define_value(enum print_arg_type field_type,
 		retval = PyObject_CallObject(handler, t);
 		if (retval == NULL)
 			handler_call_die(handler_name);
+		Py_DECREF(retval);
 	}
 
 	Py_DECREF(t);
@@ -143,6 +148,7 @@ static void define_field(enum print_arg_type field_type,
 		retval = PyObject_CallObject(handler, t);
 		if (retval == NULL)
 			handler_call_die(handler_name);
+		Py_DECREF(retval);
 	}
 
 	Py_DECREF(t);
@@ -333,6 +339,7 @@ static void python_process_tracepoint(struct perf_sample *sample,
 		retval = PyObject_CallObject(handler, t);
 		if (retval == NULL)
 			handler_call_die(handler_name);
+		Py_DECREF(retval);
 	} else {
 		handler = PyDict_GetItemString(main_dict, "trace_unhandled");
 		if (handler && PyCallable_Check(handler)) {
@@ -340,6 +347,7 @@ static void python_process_tracepoint(struct perf_sample *sample,
 			retval = PyObject_CallObject(handler, t);
 			if (retval == NULL)
 				handler_call_die("trace_unhandled");
+			Py_DECREF(retval);
 		}
 		Py_DECREF(dict);
 	}
@@ -399,6 +407,7 @@ static void python_process_general_event(struct perf_sample *sample,
 	retval = PyObject_CallObject(handler, t);
 	if (retval == NULL)
 		handler_call_die(handler_name);
+	Py_DECREF(retval);
 exit:
 	Py_DECREF(dict);
 	Py_DECREF(t);
@@ -520,8 +529,7 @@ static int python_stop_script(void)
 	retval = PyObject_CallObject(handler, NULL);
 	if (retval == NULL)
 		handler_call_die("trace_end");
-	else
-		Py_DECREF(retval);
+	Py_DECREF(retval);
 out:
 	Py_XDECREF(main_dict);
 	Py_XDECREF(main_module);
-- 
1.8.1.2



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