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

Peter Zijlstra
2010-04-19T10:39:11Z

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.