Re: [RFC][PATCH 7/7] lockdep: spin_lock_nest_lock()

Peter Zijlstra
2008-08-04T19:39:17Z

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.