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Date: Fri, 6 Jun 2014 08:15:18 -0700
From: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To: Peter Zijlstra <peterz@...radead.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>,
Mikulas Patocka <mpatocka@...hat.com>,
"James E.J. Bottomley" <jejb@...isc-linux.org>,
Helge Deller <deller@....de>,
John David Anglin <dave.anglin@...l.net>,
Parisc List <linux-parisc@...r.kernel.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
"Vinod, Chegu" <chegu_vinod@...com>,
Waiman Long <Waiman.Long@...com>,
Thomas Gleixner <tglx@...utronix.de>,
Rik van Riel <riel@...hat.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Davidlohr Bueso <davidlohr@...com>,
Peter Anvin <hpa@...or.com>, Andi Kleen <andi@...stfloor.org>,
"Chandramouleeswaran, Aswin" <aswin@...com>,
"Norton, Scott J" <scott.norton@...com>,
Jason Low <jason.low2@...com>, mingo@...nel.org
Subject: Re: [PATCH v2] introduce atomic_pointer to fix a race condition in
cancelable mcs spinlocks
On Fri, Jun 06, 2014 at 05:06:07PM +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@...radead.org> 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.
>
> Reported-by: Mikulas Patocka <mpatocka@...hat.com>
> Signed-off-by: Peter Zijlstra <peterz@...radead.org>
Reviewed-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
> ---
> kernel/Kconfig.locks | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/Kconfig.locks b/kernel/Kconfig.locks
> index 35536d9c0964..9c239e080c2d 100644
> --- a/kernel/Kconfig.locks
> +++ b/kernel/Kconfig.locks
> @@ -222,7 +222,7 @@ endif
>
> config MUTEX_SPIN_ON_OWNER
> def_bool y
> - depends on SMP && !DEBUG_MUTEXES
> + depends on SMP && !DEBUG_MUTEXES && !PARISC
>
> config ARCH_USE_QUEUE_RWLOCK
> bool
>
--
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