On Thu, Dec 17, 2015 at 03:02:12PM +0100, Peter Zijlstra wrote: > On Thu, Dec 17, 2015 at 03:26:29PM +0200, Michael S. Tsirkin wrote: > > > Note that virtio_mb() is weirdly inconsistent with virtio_[rw]mb() in > > > that they use dma_* ops for weak_barriers, while virtio_mb() uses > > > smp_mb(). > > > > It's a hack really. I think I'll clean it up a bit to > > make it more consistent. > > > > To simplify things, you may consider things before > > the optimization brought in by > > commit 9e1a27ea42691429e31f158cce6fc61bc79bb2e9 > > Author: Alexander Duyck <alexander.h.du...@redhat.com> > > 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. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
