From: Jeff Layton <jeff.layton@primarydata.com>
Date: Tue, 1 Jul 2014 07:10:41 -0400
To: Peter Zijlstra <peterz@infradead.org>
Cc: Jeff Layton <jeff.layton@primarydata.com>, bfields@fieldses.org,
        linux-nfs@vger.kernel.org, Ingo Molnar <mingo@redhat.com>
Subject: Re: [PATCH v3 071/114] lockdep: add lockdep_assert_not_held
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On Tue, 1 Jul 2014 13:07:18 +0200
Peter Zijlstra <peterz@infradead.org> wrote:

> On Tue, Jul 01, 2014 at 06:41:11AM -0400, Jeff Layton wrote:
> > Right -- in the case of something like atomic_dec_and_lock, we only
> > take the spinlock if we think the count might go to zero. So, we might
> > miss catching some places that could deadlock if the refcounts don't go
> > to zero in the testing we're doing.
> > 
> > might_lock may be what we need, but I don't see any callers of it, 
> 
> might_fault()
>   might_lock_read(&current->mm->mmap_sem)
> 
> I'm not sure we have others; but this is the one I remember providing
> this for.
> 
> > and
> > at a quick glance it doesn't appear to be disabled if debug_locks is
> > false.
> 
> The whole of lockdep gets killed, and that would include the
> lock_acquire/lock_release used to implement these.

Ok, good. Let's just drop this patch then and I'll plan to use
might_lock instead of this call.

Thanks!
-- 
Jeff Layton <jlayton@primarydata.com>