From mboxrd@z Thu Jan  1 00:00:00 1970
From: Avi Kivity <avi@redhat.com>
Subject: Re: [PATCH 1/5] Add a global synchronization point for pvclock
Date: Mon, 19 Apr 2010 13:50:44 +0300
Message-ID: <4BCC3584.1050501@redhat.com>
References: <1271356648-5108-1-git-send-email-glommer@redhat.com>	 <1271356648-5108-2-git-send-email-glommer@redhat.com>	 <4BC8CA52.4090703@goop.org> <1271673545.1674.743.camel@laptop>
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Cc: Jeremy Fitzhardinge <jeremy@goop.org>,
	Glauber Costa <glommer@redhat.com>, kvm@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	Marcelo Tosatti <mtosatti@redhat.com>,
	Zachary Amsden <zamsden@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Return-path: <linux-kernel-owner@vger.kernel.org>
In-Reply-To: <1271673545.1674.743.camel@laptop>
Sender: linux-kernel-owner@vger.kernel.org
List-Id: kvm.vger.kernel.org

On 04/19/2010 01:39 PM, Peter Zijlstra wrote:
> On Fri, 2010-04-16 at 13:36 -0700, Jeremy Fitzhardinge wrote:
>    
>>> +     do {
>>> +             last = last_value;
>>>
>>>        
>> Does this need a barrier() to prevent the compiler from re-reading
>> last_value for the subsequent lines?  Otherwise "(ret<  last)" and
>> "return last" could execute with different values for "last".
>>
>>      
> ACCESS_ONCE() is your friend.
>    

I think it's implied with atomic64_read().

-- 
error compiling committee.c: too many arguments to function