On Wed, Nov 09, 2016 at 03:38:32PM +0800, Jason Wang wrote: > We should use vq->last_avail_idx instead of vq->avail_idx in the > checking of vhost_vq_avail_empty() since latter is the cached avail > index from guest but we want to know if there's pending available > buffers in the virtqueue. > > Signed-off-by: Jason Wang <jasow...@redhat.com>
I'm not sure why is this patch here. Is it related to batching somehow? > --- > drivers/vhost/vhost.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c > index c6f2d89..fdf4cdf 100644 > --- a/drivers/vhost/vhost.c > +++ b/drivers/vhost/vhost.c > @@ -2230,7 +2230,7 @@ bool vhost_vq_avail_empty(struct vhost_dev *dev, struct > vhost_virtqueue *vq) > if (r) > return false; > > - return vhost16_to_cpu(vq, avail_idx) == vq->avail_idx; > + return vhost16_to_cpu(vq, avail_idx) == vq->last_avail_idx; > } > EXPORT_SYMBOL_GPL(vhost_vq_avail_empty); That might be OK for TX but it's probably wrong for RX where the fact that used != avail does not mean we have enough space to store the packet. Maybe we should just rename this to vhost_vq_avail_unchanged to clarify usage. > > -- > 2.7.4
