[RFC v2 4/7] powerpc: atomic: Implement xchg_* and atomic{,64}_xchg_* variants

[Peter Zijlstra]

On Thu, Oct 01, 2015 at 08:09:09AM -0700, Paul E. McKenney wrote:
> On Thu, Oct 01, 2015 at 02:24:40PM +0200, Peter Zijlstra wrote:

> > I must say I'm somewhat surprised by this level of relaxation, I had
> > expected to only loose SMP barriers, not the program order ones.
> > 
> > Is there a good argument for this?
> 
> Yes, when we say "relaxed", we really mean relaxed.  ;-)
> 
> Both the CPU and the compiler are allowed to reorder around relaxed
> operations.

Is this documented somewhere, because I completely missed this part.