Re: [PATCH v2 optional 3/3] mutex: back out architecture specificcheck for negative mutex count

[Waiman Long]

On 04/16/2013 06:05 AM, Will Deacon wrote:
> On Mon, Apr 15, 2013 at 03:37:59PM +0100, Waiman Long wrote:
> > If it is confirmed that all the supported architectures can allow a
> > negative mutex count without incorrect behavior, we can then back
> > out the architecture specific change and allow the mutex count to
> > go to any negative number. That should further reduce contention for
> > non-x86 architecture.
> >
> > If this is not the case, this patch should be dropped.
> A good starting point might be to look at the asm-generic mutex
> implementations, which clears up the majority of architectures. A cursory
> glance at mutex-dec.h suggests that it's OK to me...

I think the generic version is fine with negative mutex count. However, 
it is the architecture specific versions (we have 22 of them as of 3.8) 
that I am worry about. I just don't have enough know-how and test 
machines to verify that.

Regards,
Longman
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