static void handle_rx(struct vhost_net *net)
{
	struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_RX];
	struct vhost_virtqueue *vq = &nvq->vq;
	unsigned uninitialized_var(in), log;
	struct vhost_log *vq_log;
	struct msghdr msg = {
		.msg_name = NULL,
		.msg_namelen = 0,
		.msg_control = NULL, /* FIXME: get and handle RX aux data. */
		.msg_controllen = 0,
		.msg_flags = MSG_DONTWAIT,
	};
	struct virtio_net_hdr hdr = {
		.flags = 0,
		.gso_type = VIRTIO_NET_HDR_GSO_NONE
	};
	size_t total_len = 0;
	int err, mergeable;
	s16 headcount, nheads = 0;
	size_t vhost_hlen, sock_hlen;
	size_t vhost_len, sock_len;
	struct socket *sock;
	struct iov_iter fixup;
	__virtio16 num_buffers;

	mutex_lock(&vq->mutex);
	sock = vq->private_data;
	if (!sock)
		goto out;

	if (!vq_iotlb_prefetch(vq))
		goto out;

	vhost_disable_notify(&net->dev, vq);
	vhost_net_disable_vq(net, vq);

	vhost_hlen = nvq->vhost_hlen;
	sock_hlen = nvq->sock_hlen;

	vq_log = unlikely(vhost_has_feature(vq, VHOST_F_LOG_ALL)) ?
		vq->log : NULL;
	mergeable = vhost_has_feature(vq, VIRTIO_NET_F_MRG_RXBUF);

	while ((sock_len = vhost_net_rx_peek_head_len(net, sock->sk))) {
		sock_len += sock_hlen;
		vhost_len = sock_len + vhost_hlen;
		headcount = get_rx_bufs(vq, vq->heads + nheads, vhost_len,
					&in, vq_log, &log,
					likely(mergeable) ? UIO_MAXIOV : 1);
		/* On error, stop handling until the next kick. */
		if (unlikely(headcount < 0))
			goto out;
		/* OK, now we need to know about added descriptors. */
		if (!headcount) {
			if (unlikely(vhost_enable_notify(&net->dev, vq))) {
				/* They have slipped one in as we were
				 * doing that: check again. */
				vhost_disable_notify(&net->dev, vq);
				continue;
			}
			/* Nothing new?  Wait for eventfd to tell us
			 * they refilled. */
			goto out;
		}
		if (nvq->rx_ring)
			msg.msg_control = vhost_net_buf_consume(&nvq->rxq);
		/* On overrun, truncate and discard */
		if (unlikely(headcount > UIO_MAXIOV)) {
			iov_iter_init(&msg.msg_iter, READ, vq->iov, 1, 1);
			err = sock->ops->recvmsg(sock, &msg,
						 1, MSG_DONTWAIT | MSG_TRUNC);
			pr_debug("Discarded rx packet: len %zd\n", sock_len);
			continue;
		}
		/* We don't need to be notified again. */
		iov_iter_init(&msg.msg_iter, READ, vq->iov, in, vhost_len);
		fixup = msg.msg_iter;
		if (unlikely((vhost_hlen))) {
			/* We will supply the header ourselves
			 * TODO: support TSO.
			 */
			iov_iter_advance(&msg.msg_iter, vhost_hlen);
		}
		err = sock->ops->recvmsg(sock, &msg,
					 sock_len, MSG_DONTWAIT | MSG_TRUNC);
		/* Userspace might have consumed the packet meanwhile:
		 * it's not supposed to do this usually, but might be hard
		 * to prevent. Discard data we got (if any) and keep going. */
		if (unlikely(err != sock_len)) {
			pr_debug("Discarded rx packet: "
				 " len %d, expected %zd\n", err, sock_len);
			vhost_discard_vq_desc(vq, headcount);
			continue;
		}
		/* Supply virtio_net_hdr if VHOST_NET_F_VIRTIO_NET_HDR */
		if (unlikely(vhost_hlen)) {
			if (copy_to_iter(&hdr, sizeof(hdr),
					 &fixup) != sizeof(hdr)) {
				vq_err(vq, "Unable to write vnet_hdr "
				       "at addr %p\n", vq->iov->iov_base);
				goto out;
			}
		} else {
			/* Header came from socket; we'll need to patch
			 * ->num_buffers over if VIRTIO_NET_F_MRG_RXBUF
			 */
			iov_iter_advance(&fixup, sizeof(hdr));
		}
		/* TODO: Should check and handle checksum. */

		num_buffers = cpu_to_vhost16(vq, headcount);
		if (likely(mergeable) &&
		    copy_to_iter(&num_buffers, sizeof num_buffers,
				 &fixup) != sizeof num_buffers) {
			vq_err(vq, "Failed num_buffers write");
			vhost_discard_vq_desc(vq, headcount);
			goto out;
		}
		nheads += headcount;
		if (nheads > VHOST_RX_BATCH) {
			vhost_add_used_and_signal_n(&net->dev, vq, vq->heads,
						    nheads);
			nheads = 0;
		}
		if (unlikely(vq_log))
			vhost_log_write(vq, vq_log, log, vhost_len);
		total_len += vhost_len;
		if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
			vhost_poll_queue(&vq->poll);
			goto out;
		}
	}
	vhost_net_enable_vq(net, vq);
out:
	if (nheads)
		vhost_add_used_and_signal_n(&net->dev, vq, vq->heads,
					    nheads);
	mutex_unlock(&vq->mutex);
}