Re: [PATCH v2 RFC 1/3] documentation: Add needed ACCESS_ONCE() calls to memory-barriers.txt

Peter Zijlstra
2013-11-22T15:39:40Z

On Thu, Nov 21, 2013 at 01:31:27PM -0800, Paul E. McKenney wrote:
> From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
>
> The Documentation/memory-barriers.txt file was written before the need
> for ACCESS_ONCE() was fully appreciated. It therefore contains no
> ACCESS_ONCE() calls, which can be a problem when people lift examples
> from it. This commit therefore adds ACCESS_ONCE() calls.
>

Under the 'COMPILER BARRIER' section we state that:

"This is a general barrier - lesser varieties of compiler barrier do not
exist."

One could argue ACCESS_ONCE() is such a lesser barrier.