Subject: Re: Deadlock scenario in regulator core
From: Steven Rostedt <rostedt@goodmis.org>
To: David Collins <collinsd@codeaurora.org>
Cc: Liam Girdwood <lrg@slimlogic.co.uk>,
        Mark Brown <broonie@opensource.wolfsonmicro.com>,
        linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org,
        Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@elte.hu>
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Date: Tue, 22 Mar 2011 20:07:36 -0400
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On Tue, 2011-03-22 at 16:41 -0700, David Collins wrote:

> There seem to be very few uses of mutex_lock_nested() in the kernel.  Most
> of them use subclass = SINGLE_DEPTH_NESTING.  Would this be sufficient for
> usage in the regulator core in _notifier_call_chain (and perhaps other
> places) or should some other subclass be used?

Note, I do not know this code well enough to say. I'm assuming that an
rdevA on a rdevB->supply_list never has rdevB on its own
rdevA->supply_list.

If this is the case, and that you only ever have a lock nesting of one,
then sure, use the SINGLE_DEPTH_NESTING.

Peter or Ingo could correct me if I'm wrong.

-- Steve


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