Re: [PATCH v2] introduce atomic_pointer to fix a race condition in cancelable mcs spinlocks

[Davidlohr Bueso]

On Fri, 2014-06-06 at 17:06 +0200, Peter Zijlstra wrote:
> On Mon, Jun 02, 2014 at 10:09:35AM -0700, Linus Torvalds wrote:
> > On Mon, Jun 2, 2014 at 9:25 AM, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> > >
> > > And I can't say I'm a particular fan of these ops either, as alternative
> > > I'm almost inclined to just exclude parisc from using opt spinning.
> > 
> > Please do.
> 
> Something like so; if the rwsem stuff lands in .15 we need more for
> that, it doesn't have a convenient CONFIG symbol like this.
> 
> Linus will you take this from email, or should I get it through
> tip/locking/urgent or so?
> 
> ---
> Subject: locking, mutex: Disable optimistic spinning for PA-RISC
> 
> PA-RISC's cmpxchg is not save against normal stores and the code used
> for optimistic spinning is known broken because of this.
> 
> Disable for now.

I almost hit the send button :)

> 
> Reported-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
> Signed-off-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> ---

Reviewed-by: Davidlohr Bueso <davidlohr@xxxxxx>

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