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Subject: Re: [PATCH] 1/2 Maple: Update bus driver to allow support of VMU
	device
From: Adrian McMenamin <adrian@newgolddream.dyndns.info>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: dwmw2@infradead.org, greg@kroah.com, lethal@linux-sh.org,
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Date: Thu, 20 Mar 2008 22:52:27 +0000
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On Thu, 2008-03-20 at 15:39 -0700, Andrew Morton wrote:
> On Thu, 20 Mar 2008 22:23:17 +0000
> Adrian McMenamin <adrian@newgolddream.dyndns.info> wrote:
> 
> > 
> > > urgh, down_trylock().  And a secret, undocumented one too.
> > > 
> > > A trylock is always an exceptional thing.  How is *any* reader of this code
> > > supposed to work out what the heck it's doing there?  Convert it into
> > > down(), run the code and decrypt the lockdep warnings, I suspect.
> > > 
> > > <looks>
> > > 
> > > Nope, I can't see any other lock being held when we call this function.
> > > 
> > > The trylocks are an utter mystery to me.  Please don't write mysterious
> > > code.
> > > 
> > 
> > OK, I am sure this is my problem but I have no idea why you are
> > describing down_trylock as undocumented
> 
> I'm describing your use of it!  I'm sitting here trying to work out why on
> earth this code is using the highly unusual (and highly suspicious) trylock
> idiom and this is far from clear.
> 

OK, I understand your point now. Some comments wouldn't go amiss, for
sure.