static int xenvif_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
	struct xenvif *vif = netdev_priv(dev);

	BUG_ON(skb->dev != dev);

	if (vif->netbk == NULL)
		goto drop;

	/* Drop the packet if the target domain has no receive buffers. */
	if (!xenvif_rx_schedulable(vif))
		goto drop;

	/* Reserve ring slots for the worst-case number of fragments. */
	vif->rx_req_cons_peek += xen_netbk_count_skb_slots(vif, skb);
	xenvif_get(vif);

	if (vif->can_queue && xen_netbk_must_stop_queue(vif))
		netif_stop_queue(dev);

	xen_netbk_queue_tx_skb(vif, skb);

	return NETDEV_TX_OK;

 drop:
	vif->dev->stats.tx_dropped++;
	dev_kfree_skb(skb);
	return NETDEV_TX_OK;
}
static int xenvif_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
	struct xenvif *vif = netdev_priv(dev);

	BUG_ON(skb->dev != dev);

	if (vif->netbk == NULL)
		goto drop;

	 
	if (!xenvif_rx_schedulable(vif))
		goto drop;

	 
	vif->rx_req_cons_peek += xen_netbk_count_skb_slots(vif, skb);
	xenvif_get(vif);

	if (vif->can_queue && xen_netbk_must_stop_queue(vif))
		netif_stop_queue(dev);

	xen_netbk_queue_tx_skb(vif, skb);

	return NETDEV_TX_OK;

 drop:
	vif->dev->stats.tx_dropped++;
	dev_kfree_skb(skb);
	return NETDEV_TX_OK;
}