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

From Peter Zijlstra <peterz@infradead.org>
Newsgroups linux.kernel
Subject Re: [RFC v2 6/7] powerpc: atomic: Make atomic{,64}_xchg and xchg a full barrier
Date 2015-10-02 07:40 +0200
Message-ID <qf1ex-2v1-9@gated-at.bofh.it> (permalink)
References <q9nhM-vs-7@gated-at.bofh.it> <q9nhO-vs-47@gated-at.bofh.it> <qeL9N-3Vj-21@gated-at.bofh.it> <qf1ex-2v1-11@gated-at.bofh.it>
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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@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.
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Re: [RFC v2 6/7] powerpc: atomic: Make atomic{,64}_xchg and xchg a  full barrier Peter Zijlstra <peterz@infradead.org> - 2015-10-01 14:30 +0200
  Re: [RFC v2 6/7] powerpc: atomic: Make atomic{,64}_xchg and xchg a  full barrier Peter Zijlstra <peterz@infradead.org> - 2015-10-02 07:40 +0200

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