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From: Peter Zijlstra <peterz@infradead.org>
To: Mark Brown <broonie@opensource.wolfsonmicro.com>
Cc: Steven Rostedt <rostedt@goodmis.org>,
	David Collins <collinsd@codeaurora.org>,
	Liam Girdwood <lrg@slimlogic.co.uk>,
	linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org,
	Ingo Molnar <mingo@elte.hu>
Subject: Re: Deadlock scenario in regulator core
Date: Fri, 25 Mar 2011 11:59:16 +0100	[thread overview]
Message-ID: <1301050756.2250.190.camel@laptop> (raw)
In-Reply-To: <20110323104230.GA778@opensource.wolfsonmicro.com>

On Wed, 2011-03-23 at 10:42 +0000, Mark Brown wrote:
> 
> That's helpful, though it doesn't really say anything about how one
> picks subclass? 

With care ;-)

Its most useful for recursive use of the same lock class, typically we
only have 2 locks held and we can use the SINGLE_DEPTH_NESTING thing.
Some few sites use subclasses for larger things, some are ok, some are
dubious (ext4 comes to mind).

And like said in the other email, be careful with lockdep annotations,
you can actually annotate real deadlocks away.


  reply	other threads:[~2011-03-25 10:57 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-03-22 22:02 Deadlock scenario in regulator core David Collins
2011-03-22 22:31 ` Mark Brown
2011-03-22 23:30   ` David Collins
2011-03-22 23:45     ` Mark Brown
2011-03-22 22:37 ` Steven Rostedt
2011-03-22 23:08   ` David Collins
2011-03-22 23:19     ` Steven Rostedt
2011-03-22 23:41       ` David Collins
2011-03-23  0:07         ` Steven Rostedt
2011-03-23  0:11           ` Mark Brown
2011-03-25 10:55           ` Peter Zijlstra
2011-03-23  0:01       ` Mark Brown
2011-03-23  0:38         ` Steven Rostedt
2011-03-23 10:42           ` Mark Brown
2011-03-25 10:59             ` Peter Zijlstra [this message]
2011-03-22 22:43 ` Mark Brown

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