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.duyck@xxxxxxxxxx> > > 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. _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
