linux-kernel - Re: [PATCH] tracing/filters: Defer pred allocation

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Date:	Mon, 31 Aug 2009 19:41:08 +0200
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Li Zefan <lizf@...fujitsu.com>
Cc:	Ingo Molnar <mingo@...e.hu>, Steven Rostedt <rostedt@...dmis.org>,
	Tom Zanussi <tzanussi@...il.com>,
	Masami Hiramatsu <mhiramat@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] tracing/filters: Defer pred allocation

On Mon, Aug 31, 2009 at 04:49:41PM +0800, Li Zefan wrote:
> @@ -1094,6 +1118,10 @@ int apply_event_filter(struct ftrace_event_call *call, char *filter_string)
>  
>  	mutex_lock(&event_mutex);
>  
> +	err = init_preds(call);
> +	if (err)
> +		goto out_unlock;



Hmm, but what happens if the filter already has its preds initialized
by a previous filter?

The first thing that init_preds() does is:

filter = call->filter = kzalloc(sizeof(*filter), GFP_KERNEL);

That looks like a memory leak.


>  	if (!strcmp(strstrip(filter_string), "0")) {
>  		filter_disable_preds(call);
>  		remove_filter_string(call->filter);
> @@ -1139,6 +1167,10 @@ int apply_subsystem_event_filter(struct event_subsystem *system,
>  
>  	mutex_lock(&event_mutex);
>  
> +	err = init_subsystem_preds(system);


Whereas this one has a check:
	if (!call->filter)
		alloc...



> +	if (err)
> +		goto out_unlock;
> +
>  	if (!strcmp(strstrip(filter_string), "0")) {
>  		filter_free_subsystem_preds(system, FILTER_DISABLE_ALL);
>  		remove_filter_string(system->filter);
> diff --git a/kernel/trace/trace_export.c b/kernel/trace/trace_export.c
> index 029a91f..df1bf6e 100644
> --- a/kernel/trace/trace_export.c
> +++ b/kernel/trace/trace_export.c
> @@ -135,7 +135,6 @@ __attribute__((section("_ftrace_events"))) event_##call = {		\
>  static int ftrace_raw_init_event_##call(void)				\
>  {									\
>  	INIT_LIST_HEAD(&event_##call.fields);				\
> -	init_preds(&event_##call);					\
>  	return 0;							\
>  }									\
>  
> -- 
> 1.6.3
> 


Other than the above doubts, that looks good.

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