linux-kernel - Re: [PATCH][GIT PULL] ftrace: Add function names to dangling } in function graph tracer

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Message-ID: <1267298703.6328.181.camel@gandalf.stny.rr.com>
Date:	Sat, 27 Feb 2010 14:25:03 -0500
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Frederic Weisbecker <fweisbec@...il.com>
Cc:	LKML <linux-kernel@...r.kernel.org>, Ingo Molnar <mingo@...e.hu>,
	Tim Bird <tim.bird@...sony.com>
Subject: Re: [PATCH][GIT PULL] ftrace: Add function names to dangling } in
 function graph tracer

On Sat, 2010-02-27 at 11:02 +0100, Frederic Weisbecker wrote:

> >  		/*
> >  		 * Comments display at + 1 to depth. Since
> >  		 * this is a leaf function, keep the comments
> >  		 * equal to this depth.
> >  		 */
> > -		*depth = call->depth - 1;
> > +		cpu_data->depth = call->depth - 1;
> > +
> > +		/* No need to keep this function around for this depth */
> > +		if (call->depth < FTRACE_RETFUNC_DEPTH)
> 
> 
> 
> Do you really need to check that? call->depth >= FTRACE_RETFUNC_DEPTH
> are not recorded.
> 
> 

Call me paranoid, but working inside the kernel makes me paranoid. If
for some reason a trace gets corrupted here, not doing this check can
cause a kernel oops.

> 
> > +			cpu_data->enter_funcs[call->depth] = 0;

cpu_data->enter_funcs[102340320211] = 0;

would be bad ;-)


Hmm, I should also make sure depth is not less than zero. I'll send a
new patch to do that too.

-- Steve

> >  	}
> >  

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