From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: Re: [PATCH v2] introduce atomic_pointer to fix a race condition in cancelable mcs spinlocks Date: Fri, 6 Jun 2014 17:06:07 +0200 Message-ID: <20140606150607.GT13930@laptop.programming.kicks-ass.net> References: <20140602162525.GH16155@laptop.programming.kicks-ass.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Mikulas Patocka , "James E.J. Bottomley" , Helge Deller , John David Anglin , Parisc List , Linux Kernel Mailing List , Paul McKenney , "Vinod, Chegu" , Waiman Long , Thomas Gleixner , Rik van Riel , Andrew Morton , Davidlohr Bueso , Peter Anvin , Andi Kleen , "Chandramouleeswaran, Aswin" , "Norton, Scott J" , Jason Low , mingo@kernel.org To: Linus Torvalds Return-path: In-Reply-To: List-ID: List-Id: linux-parisc.vger.kernel.org On Mon, Jun 02, 2014 at 10:09:35AM -0700, Linus Torvalds wrote: > On Mon, Jun 2, 2014 at 9:25 AM, Peter Zijlstra 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 Signed-off-by: Peter Zijlstra --- 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