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

Avi Kivity
2010-04-19T14:33:57Z

On 04/19/2010 05:21 PM, Glauber Costa wrote:
>
>> Oh yes, just trying to avoid a patch with both atomic64_read() and
>> ACCESS_ONCE().
>>
> you're mixing the private version of the patch you saw with this one.
> there isn't any atomic reads in here. I'll use a barrier then
>

This patch writes last_value atomically, but reads it non-atomically. A
barrier is insufficient.

--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.