[NET] front: clean up transmit queue waking

Signed-off-by: Keir Fraser <keir@xensource.com>

diff --git a/linux-2.6-xen-sparse/drivers/xen/netfront/netfront.c b/linux-2.6-xen-sparse/drivers/xen/netfront/netfront.c
index d7b2bbc83e4e23c2729f4fd147240fce1efe432c..0017a90794367bb7f6168c115e724ec6977b3c19 100644 (file)
--- a/linux-2.6-xen-sparse/drivers/xen/netfront/netfront.c
+++ b/linux-2.6-xen-sparse/drivers/xen/netfront/netfront.c
@@ -449,9 +449,20 @@ static int network_open(struct net_device *dev)
        return 0;
 }
 
+static inline void network_maybe_wake_tx(struct net_device *dev)
+{
+       struct netfront_info *np = netdev_priv(dev);
+
+       if (unlikely(netif_queue_stopped(dev)) &&
+           !RING_FULL(&np->tx) &&
+           !gnttab_empty_grant_references(&np->gref_tx_head) &&
+           likely(netif_running(dev)))
+               netif_wake_queue(dev);
+}
+
 static void network_tx_buf_gc(struct net_device *dev)
 {
-       RING_IDX i, prod;
+       RING_IDX cons, prod;
        unsigned short id;
        struct netfront_info *np = netdev_priv(dev);
        struct sk_buff *skb;
@@ -463,15 +474,15 @@ static void network_tx_buf_gc(struct net_device *dev)
                prod = np->tx.sring->rsp_prod;
                rmb(); /* Ensure we see responses up to 'rp'. */
 
-               for (i = np->tx.rsp_cons; i != prod; i++) {
-                       id  = RING_GET_RESPONSE(&np->tx, i)->id;
+               for (cons = np->tx.rsp_cons; cons != prod; cons++) {
+                       id  = RING_GET_RESPONSE(&np->tx, cons)->id;
                        skb = np->tx_skbs[id];
                        if (unlikely(gnttab_query_foreign_access(
                                np->grant_tx_ref[id]) != 0)) {
                                printk(KERN_ALERT "network_tx_buf_gc: warning "
                                       "-- grant still in use by backend "
                                       "domain.\n");
-                               goto out;
+                               break; /* bail immediately */
                        }
                        gnttab_end_foreign_access_ref(
                                np->grant_tx_ref[id], GNTMAP_readonly);
@@ -495,15 +506,9 @@ static void network_tx_buf_gc(struct net_device *dev)
                np->tx.sring->rsp_event =
                        prod + ((np->tx.sring->req_prod - prod) >> 1) + 1;
                mb();
-       } while (prod != np->tx.sring->rsp_prod);
+       } while ((cons == prod) && (prod != np->tx.sring->rsp_prod));
 
- out:
-       if (unlikely(netif_queue_stopped(dev)) &&
-           ((np->tx.sring->req_prod - prod) < NET_TX_RING_SIZE) &&
-           !gnttab_empty_grant_references(&np->gref_tx_head)) {
-               if (likely(netif_running(dev)))
-                       netif_wake_queue(dev);
-       }
+       network_maybe_wake_tx(dev);
 }
 
 
@@ -695,9 +700,8 @@ static int network_start_xmit(struct sk_buff *skb, struct net_device *dev)
        network_tx_buf_gc(dev);
 
        if (RING_FULL(&np->tx) ||
-           gnttab_empty_grant_references(&np->gref_tx_head)) {
+           gnttab_empty_grant_references(&np->gref_tx_head))
                netif_stop_queue(dev);
-       }
 
        spin_unlock_irq(&np->tx_lock);
 
@@ -1043,8 +1047,7 @@ static void network_connect(struct net_device *dev)
        notify_remote_via_irq(np->irq);
        network_tx_buf_gc(dev);
 
-       if (netif_running(dev))
-               netif_start_queue(dev);
+       network_maybe_wake_tx(dev);
 
        spin_unlock(&np->rx_lock);
        spin_unlock_irq(&np->tx_lock);