Message-ID: <538CB78A.8090500@hp.com>
Date: Mon, 02 Jun 2014 13:42:34 -0400
From: Waiman Long <waiman.long@hp.com>
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To: Davidlohr Bueso <davidlohr@hp.com>
CC: Linus Torvalds <torvalds@linux-foundation.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Mikulas Patocka <mpatocka@redhat.com>,
        "James E.J. Bottomley" <jejb@parisc-linux.org>,
        Helge Deller <deller@gmx.de>, John David Anglin <dave.anglin@bell.net>,
        Parisc List <linux-parisc@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Paul McKenney <paulmck@linux.vnet.ibm.com>,
        "Vinod, Chegu" <chegu_vinod@hp.com>,
        Thomas Gleixner <tglx@linutronix.de>, Rik van Riel <riel@redhat.com>,
        Andrew Morton <akpm@linux-foundation.org>, Peter Anvin <hpa@zytor.com>,
        Andi Kleen <andi@firstfloor.org>,
        "Chandramouleeswaran, Aswin" <aswin@hp.com>,
        "Norton, Scott J" <scott.norton@hp.com>, Jason Low <jason.low2@hp.com>
Subject: Re: [PATCH v2] introduce atomic_pointer to fix a race condition in
 cancelable mcs spinlocks
References: <alpine.LRH.2.02.1406011342470.20831@file01.intranet.prod.int.rdu2.redhat.com>  <alpine.LRH.2.02.1406021158360.20627@file01.intranet.prod.int.rdu2.redhat.com>  <20140602162525.GH16155@laptop.programming.kicks-ass.net>  <CA+55aFzwrqkwD=G=w2m7TdXTpsMFjV7XUMXv5DMPGr=5x5YGCQ@mail.gmail.com> <1401729145.5185.5.camel@buesod1.americas.hpqcorp.net>
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On 06/02/2014 01:12 PM, Davidlohr Bueso wrote:
> On Mon, 2014-06-02 at 10:09 -0700, Linus Torvalds wrote:
>> On Mon, Jun 2, 2014 at 9:25 AM, Peter Zijlstra<peterz@infradead.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.
> I agree, this is the best way out of this mess. Furthermore, it would
> also be nice to consolidate opt spinning in a common CONFIG option --
> right now mutexes and rwsems create their own dependencies.
>

I would suggest adding a RWSEM_SPIN_ON_OWNER to control opt spinning in 
rwsem. Currently MUTEX_SPIN_ON_OWNER is doing that for mutex, and it is 
disabled when mutex debugging is turned on. So I think it is better to 
allow them to be disabled separately.

-Longman
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