[RFC v2 6/7] powerpc: atomic: Make atomic{,64}_xchg and xchg a full barrier

[Peter Zijlstra]

On Fri, Oct 02, 2015 at 07:19:04AM +0800, Boqun Feng wrote:
> Hi Peter,
> 
> Please forgive me for the format of my reply. I'm travelling,
> and replying from my phone.
> 
> 2015年10月1日 下午7:28，"Peter Zijlstra" <peterz at infradead.org>写道：
> >
> > On Wed, Sep 16, 2015 at 11:49:34PM +0800, Boqun Feng wrote:
> > > According to memory-barriers.txt, xchg and its atomic{,64}_ versions
> > > need to imply a full barrier, however they are now just RELEASE+ACQUIRE,
> > > which is not a full barrier.
> > >
> > > So remove the definition of xchg(), and let __atomic_op_fence() build
> > > the full-barrier versions of these operations.
> >
> > Do you want to do a patch for -stable fixing the current implementation?
> 
> Good idea! I didn't think of this before, and I'd love to do the patch,
> but thing is that I'm not able to use my laptop until Oct 10th.
> I will send the patch once I'm back.
> Does that work for you?

Sure, no hurry.