Re: [PATCH 1/5] x86/percpu: Differentiate this_cpu_{}() and __this_cpu_{}()

[Peter Zijlstra]

On Wed, Feb 27, 2019 at 11:41:31AM -0800, Linus Torvalds wrote:
> On Wed, Feb 27, 2019 at 9:57 AM Nadav Amit <namit@xxxxxxxxxx> wrote:
> >
> > Iâll have a look at some specific function assembly, but overall, the â+mâ
> > approach might prevent even more code optimizations than the âvolatileâ one.
> 
> Ok, that being the case, let's forget that patch.
> 
> I still wonder about the added volatiles to the xadd/cmpxchg cases,
> which already had the "memory" clobber which should make the volatile
> immaterial..

That was mostly me being OCD style consistent; but also notice that the
atomic ops also often have volatile even though they have a memory
clobber.