linux-kernel - Re: does gcc gives a false warning in kernel/trace/trace_events

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Message-ID: <1346952676.1680.44.camel@gandalf.local.home>
Date:	Thu, 06 Sep 2012 13:31:16 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Toralf Förster <toralf.foerster@....de>
Cc:	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...hat.com>,
	Linux Kernel <linux-kernel@...r.kernel.org>
Subject: Re: does gcc gives a false warning in
 kernel/trace/trace_events_filter.c ?

On Thu, 2012-09-06 at 18:35 +0200, Toralf Förster wrote:

> I filed a bug report
> 
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54495
> and got this answer : 
> 
> --- Comment #1 from Hans-Peter Nilsson <hp at gcc dot gnu.org> 2012-09-05 22:14:00 UTC ---
> But if the call to ftrace_function_filter_re sets re_cnt to 0, then ret indeed
> will be used uninitialized AFAICT.  What am I missing?
> 

That I think we are looking at two different code bases ;-)

I've been looking at what's been queued for 3.7 and not what's in
mainline. If you look at tip/master, or even linux-next, you'll find:

commit 92d8d4a8b0f "tracing/filter: Add missing initialization"

Which does:

 static int __ftrace_function_set_filter(int filter, char *buf, int len,
                                        struct function_filter_data *data)
 {
-       int i, re_cnt, ret;
+       int i, re_cnt, ret = -EINVAL;
        int *reset;
        char **re;


Thus, you were correct. This could have been marked urgent, but as it
isn't that big of a deal I just queued it for the next merge window.

-- Steve


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