linux-kernel - Re: [BUG] ftrace: available_filter_functions empty after unloading module

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Date:	Thu, 13 Dec 2012 14:39:29 -0500
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Piotr Haber <phaber@...adcom.com>
Cc:	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...hat.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [BUG] ftrace: available_filter_functions empty after unloading
 module

On Thu, 2012-12-13 at 08:34 -0500, Steven Rostedt wrote:
> On Mon, 2012-12-10 at 12:45 +0100, Piotr Haber wrote:
> 
> > > So you unloaded a module that you were tracing, correct? Hmm, the
> > > warning that you hit was an accounting error. The accounting of what
> > > functions are traced and what isn't. For some reason it tried to disable
> > > a function that wasn't being traced.
> > Yes, it happens when i unload a module that i traced before
> > 
> > > Can you easily reproduce this? If so, can you give my your .config and
> > > the steps you used to trigger it.
> > Not 100% but it happens often enough to be annoying
> > Attached is the config
> > As for reproduction, i load the brcmsmac module, add all it symbols to
> > set_ftrace_filter, associate with AP and unload the module
> > nothing fancy, i use 'function' tracer
> 
> Thanks, I'll see if I can reproduce it.

Can you tell me exactly what steps you took too?

Did you start function tracing before loading the module?

For example, did you do something like:

echo function > current_tracer
modprobe brcmsmac
echo :mod:brcmsmac > set_ftrace_filter
echo 0 > tracing_on
rmmod brcmsmac

??

Thanks,

-- Steve


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