[PATCH 5/9] locking/qrwlock: remove redundant cmpxchg barriers on writer slow-path

[Peter Zijlstra]

On Tue, Jul 07, 2015 at 06:24:21PM +0100, Will Deacon wrote:
> +#ifndef cmpxchg_relaxed
> +# define cmpxchg_relaxed	cmpxchg
> +#endif

Should we collate this _relaxed stuff and make it 'official' instead of
these ad-hoc/in-situ things?

There's more archs that can usefully implement them than seem to have
implemented them atm. Of course that means someone doing a full arch/*
sweep, but hey.. :-)