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

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Message-ID: <1401893046.1673.12.camel@leonhard>
Date:	Wed, 04 Jun 2014 23:44:06 +0900
From:	Namhyung Kim <namhyung@...nel.org>
To:	Joseph Schuchart <joseph.schuchart@...dresden.de>
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, jolsa@...hat.com
Subject: Re: [PATCH 1/3] Add missing calls to Py_DECREF

Hi Joseph,

(Adding Jiri Olsa to CC list as he's maintaining the tooling part as of
now..)

2014-06-04 (수), 14:07 +0200, Joseph Schuchart:
> 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

Acked-by: Namhyung Kim <namhyung@...nel.org>

Just nitpicks below..

> ---
>  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;

Why is this extra decl line needed?  What about just adding the NORETURN
marker to the function definition?


>  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

Please use C-style /* ... */ comments.

Thanks,
Namhyung


> +	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);



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