Re: [PATCH 2/4] arch: Add lightweight memory barriers fast_rmb() and fast_wmb()

Linus Torvalds
2014-11-17T20:52:17Z

On Mon, Nov 17, 2014 at 9:18 AM, Alexander Duyck
<alexander.h.duyck@redhat.com> wrote:
> There are a number of situations where the mandatory barriers rmb() and
> wmb() are used to order memory/memory operations in the device drivers
> and those barriers are much heavier than they actually need to be.

Ugh. I absolutely despise the name.

It's not "fast". It's just limited. It's the same as "smp_*mb()", in
that it works on cacheable memory, but it actually stays around even
for non-SMP builds.

So I think the name is actively misleading.

Naming should be about what it does, not about some kind of PR thing
that confuses people into thinking it's "better".

Maybe "dma_*mb()" would be acceptable, and ends up having the same
naming convention as "smb_*mb()", and explains what it's about.

And yes, in the same spirit, it would probably be good to try to
eventually get rid of the plain "*mb()" functions, and perhaps call
them "mmio_*mb()" to clarify that they are about ordering memory wrt
mmio.

Hmm?

Linus