Re: [PATCH v2 02/24] virtio: Use weaker barriers

-------if (likely(nb_enqueued)) {
------->-------virtio_wmb();
------->-------if (unlikely(virtqueue_kick_prepare(rxvq))) {
------->------->-------virtqueue_notify(rxvq);
------->------->-------PMD_RX_LOG(DEBUG, "Notified\n");
------->-------}
-------}
-------vq_update_avail_idx(rxvq);

Two confuses for the modification here:

1.
why notify host without updating avail idx?
Will this cause potential deadlock?

2.
Why update avail index even no packets are enqueued?