linux-kernel - Re: [for-next-3.11][PATCH 8/8] ftrace: Clear module traced functions on unload module

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Message-ID: <1375205989.6580.66.camel@gandalf.local.home>
Date:	Tue, 30 Jul 2013 13:39:49 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	linux-kernel@...r.kernel.org
Cc:	Ingo Molnar <mingo@...nel.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	Oleg Nesterov <oleg@...hat.com>,
	Jörn Engel <joern@...fs.org>,
	Dave Jones <davej@...hat.com>,
	Steve Hodgson <steve@...estorage.com>
Subject: Re: [for-next-3.11][PATCH 8/8] ftrace: Clear module traced
 functions on unload module

On Tue, 2013-07-30 at 07:27 -0400, Steven Rostedt wrote:

> The solution here is on module unload, look at all the registered funtion
> callbacks and remove any hash entry that points to any function in the
> module that is about to be removed.

There's another bug that is very similar to this one. I originally did a
ref count to ops, but I didn't really like it (it was included in what
Steve tested). While looking at other solutions I think I have something
that may be a bit better. It wont clear the trace on module reload, but
it can reenable the trace if a module is loaded with a function at the
same address that was traced before.

Sure this may be a bit confusing if another module gets traced, but it
allows for tracing functions on module load, which is useful.

I'm working on a new patch and hopefully Steve can test that one too.

Thanks,

-- Steve

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