linux-kernel - Re: [PATCH 1/5] Add a global synchronization point for pvclock

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Date:	Mon, 19 Apr 2010 13:50:44 +0300
From:	Avi Kivity <avi@...hat.com>
To:	Peter Zijlstra <peterz@...radead.org>
CC:	Jeremy Fitzhardinge <jeremy@...p.org>,
	Glauber Costa <glommer@...hat.com>, kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Marcelo Tosatti <mtosatti@...hat.com>,
	Zachary Amsden <zamsden@...hat.com>
Subject: Re: [PATCH 1/5] Add a global synchronization point for pvclock

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

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