Re: [Qemu-devel] [PATCH] virtio_ring: use smp_store_mb

[Peter Zijlstra]

On Thu, Dec 17, 2015 at 04:34:57PM +0200, Michael S. Tsirkin wrote:
> On Thu, Dec 17, 2015 at 03:02:12PM +0100, Peter Zijlstra wrote:

> > >   commit 9e1a27ea42691429e31f158cce6fc61bc79bb2e9
> > >   Author: Alexander Duyck <address@hidden>
> > >   Date:   Mon Apr 13 21:03:49 2015 +0930
> > > 
> > >       virtio_ring: Update weak barriers to use dma_wmb/rmb
> > 
> > That commit doesn't make any sense. dma_*mb() explicitly does _NOT_
> > cover the smp_*mb() part.
> > 
> > Again, look at the ARM definitions, the smp_*mb() primitives use the
> > inner coherence stuff, while the dma_*mb() primitives use the outer
> > coherent stuff.
> 
> Does outer coherent imply inner coherent?
> 
> > the *mb() primitives cover both.

I do not think so, but lets add Will, he dreams this stuff.