[RFC PATCH] locking/atomics/powerpc: Introduce optimized cmpxchg_release() family of APIs for PowerPC

[Benjamin Herrenschmidt]

On Sat, 2018-05-05 at 12:00 +0200, Ingo Molnar wrote:
> This clearly suggests that PPC_RELEASE_BARRIER is in active use and 'lwsync' is 
> the 'release barrier' instruction, if I interpreted that right.

The closest to one we got.

The semantics are that it orders all load/store pairs to cachable
storage except store+load.

Cheers,
Ben.