Subject: Re: [RFC][PATCH 7/7] lockdep: spin_lock_nest_lock()
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>, David Miller <davem@davemloft.net>,
       hugh@veritas.com, mingo@elte.hu, akpm@linux-foundation.org,
       linux-kernel@vger.kernel.org, davej@redhat.com
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	 <20080804131012.246115111@chello.nl>  <48974512.7000206@goop.org>
	 <1217876046.3589.61.camel@twins> <489757EC.3000309@goop.org>
	 <alpine.LFD.1.10.0808041230070.3340@nehalem.linux-foundation.org>
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Date: Mon, 04 Aug 2008 21:39:02 +0200
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On Mon, 2008-08-04 at 12:31 -0700, Linus Torvalds wrote:
> 
> On Mon, 4 Aug 2008, Jeremy Fitzhardinge wrote:
> > 
> > OK.  I don't actually need to do this, but I was asking for completeness.  But
> > to clarify, you only need to do the reverse unlock if you do it after
> > unlocking the outer lock?  If you're still holding the outer lock, you can
> > unlock in any order?
> 
> Release order should always be totally irrelevant, whether you hold outer 
> locks or not. Only the order of _getting_ locks matter.
> 
> And yes, if there is an outer lock, even the order of getting locks is 
> irrelevant, as long as anybody who gets more than one inner lock always 
> holds the outer one.

I agree, its just non-trivial to convince lockdep of this. I can give it
a go though.

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