static void xennet_tx_buf_gc(struct net_device *dev)
{
	RING_IDX cons, prod;
	unsigned short id;
	struct netfront_info *np = netdev_priv(dev);
	struct sk_buff *skb;

	BUG_ON(!netif_carrier_ok(dev));

	do {
		prod = np->tx.sring->rsp_prod;
		rmb(); /* Ensure we see responses up to 'rp'. */

		for (cons = np->tx.rsp_cons; cons != prod; cons++) {
			struct xen_netif_tx_response *txrsp;

			txrsp = RING_GET_RESPONSE(&np->tx, cons);
			if (txrsp->status == NETIF_RSP_NULL)
				continue;

			id  = txrsp->id;
			skb = np->tx_skbs[id].skb;
			if (unlikely(gnttab_query_foreign_access(
				np->grant_tx_ref[id]) != 0)) {
				printk(KERN_ALERT "xennet_tx_buf_gc: warning "
				       "-- grant still in use by backend "
				       "domain.\n");
				BUG();
			}
			gnttab_end_foreign_access_ref(
				np->grant_tx_ref[id], GNTMAP_readonly);
			gnttab_release_grant_reference(
				&np->gref_tx_head, np->grant_tx_ref[id]);
			np->grant_tx_ref[id] = GRANT_INVALID_REF;
			add_id_to_freelist(&np->tx_skb_freelist, np->tx_skbs, id);
			dev_kfree_skb_irq(skb);
		}

		np->tx.rsp_cons = prod;

		/*
		 * Set a new event, then check for race with update of tx_cons.
		 * Note that it is essential to schedule a callback, no matter
		 * how few buffers are pending. Even if there is space in the
		 * transmit ring, higher layers may be blocked because too much
		 * data is outstanding: in such cases notification from Xen is
		 * likely to be the only kick that we'll get.
		 */
		np->tx.sring->rsp_event =
			prod + ((np->tx.sring->req_prod - prod) >> 1) + 1;
		mb();		/* update shared area */
	} while ((cons == prod) && (prod != np->tx.sring->rsp_prod));

	xennet_maybe_wake_tx(dev);
}
Beispiel #2
0
static void xennet_tx_buf_gc(struct net_device *dev)
{
	RING_IDX cons, prod;
	unsigned short id;
	struct netfront_info *np = netdev_priv(dev);
	struct sk_buff *skb;

	BUG_ON(!netif_carrier_ok(dev));

	do {
		prod = np->tx.sring->rsp_prod;
		rmb(); 

		for (cons = np->tx.rsp_cons; cons != prod; cons++) {
			struct xen_netif_tx_response *txrsp;

			txrsp = RING_GET_RESPONSE(&np->tx, cons);
			if (txrsp->status == NETIF_RSP_NULL)
				continue;

			id  = txrsp->id;
			skb = np->tx_skbs[id].skb;
			if (unlikely(gnttab_query_foreign_access(
				np->grant_tx_ref[id]) != 0)) {
				printk(KERN_ALERT "xennet_tx_buf_gc: warning "
				       "-- grant still in use by backend "
				       "domain.\n");
				BUG();
			}
			gnttab_end_foreign_access_ref(
				np->grant_tx_ref[id], GNTMAP_readonly);
			gnttab_release_grant_reference(
				&np->gref_tx_head, np->grant_tx_ref[id]);
			np->grant_tx_ref[id] = GRANT_INVALID_REF;
			add_id_to_freelist(&np->tx_skb_freelist, np->tx_skbs, id);
			dev_kfree_skb_irq(skb);
		}

		np->tx.rsp_cons = prod;

		
		np->tx.sring->rsp_event =
			prod + ((np->tx.sring->req_prod - prod) >> 1) + 1;
		mb();		
	} while ((cons == prod) && (prod != np->tx.sring->rsp_prod));

	xennet_maybe_wake_tx(dev);
}