From mboxrd@z Thu Jan  1 00:00:00 1970
From: Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH v9 03/19] qspinlock: Add pending bit
Date: Fri, 18 Apr 2014 10:13:45 +0200
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To: Waiman Long <waiman.long@hp.com>
Cc: linux-arch@vger.kernel.org, Rik van Riel <riel@redhat.com>, Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>, Gleb Natapov <gleb@redhat.com>, kvm@vger.kernel.org, Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>, Scott J Norton <scott.norton@hp.com>, x86@kernel.org, Paolo Bonzini <paolo.bonzini@gmail.com>, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, Ingo Molnar <mingo@redhat.com>, Chegu Vinod <chegu_vinod@hp.com>, David Vrabel <david.vrabel@citrix.com>, "H. Peter Anvin" <hpa@zytor.com>, xen-devel@lists.xenproject.org, Thomas Gleixner <tglx@linutronix.de>, "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>, Linus Torvalds <torvalds@linux-foundation.org>, Oleg Nesterov <oleg@redhat.com>
List-Id: virtualization@lists.linuxfoundation.org

On Thu, Apr 17, 2014 at 05:20:31PM -0400, Waiman Long wrote:
> >>+	while ((val = atomic_read(&lock->val))&  _Q_LOCKED_MASK)
> >>+		arch_mutex_cpu_relax();
> >That was a cpu_relax().
> 
> Yes, but arch_mutex_cpu_relax() is the same as cpu_relax() for x86.

Yeah, so why bother typing more?

Let the s390 people sort that if/when they try and make this work for
them.