On Fri, Jan 20, 2012 at 04:17:08PM +0800, Jason Wang wrote: > Use virtio_mb() to make sure the available index to be exposed before > checking the the avail event. Otherwise we may get stale value of > avail event in guest and never kick the host after. > > Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx> Good catch. Note: this fixes a bug introduced by ee7cd8981e15bcb365fc762afe3fc47b8242f630. Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx> > --- > drivers/virtio/virtio_ring.c | 6 +++--- > 1 files changed, 3 insertions(+), 3 deletions(-) > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > index 78428a8..07d9360 100644 > --- a/drivers/virtio/virtio_ring.c > +++ b/drivers/virtio/virtio_ring.c > @@ -308,9 +308,9 @@ bool virtqueue_kick_prepare(struct virtqueue *_vq) > bool needs_kick; > > START_USE(vq); > - /* Descriptors and available array need to be set before we expose the > - * new available array entries. */ > - virtio_wmb(vq); > + /* We need expose available array entries before checking avail Nit: We need expose -> Need to expose > + * event. */ > + virtio_mb(vq); > > old = vq->vring.avail->idx - vq->num_added; > new = vq->vring.avail->idx; _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
