[PATCH] skge: compute available ring buffers

Don't need to keep track of available buffers, it is simpler
to just compute the value (ala e1000). Don't need tes on link up
because should always have available buffers then.
Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

drivers/net/skge.c

@@ -847,8 +847,7 @@ static void skge_link_up(struct skge_port *skge)
 		    LED_BLK_OFF|LED_SYNC_OFF|LED_ON);
 
 	netif_carrier_on(skge->netdev);
-	if (skge->tx_avail > MAX_SKB_FRAGS + 1)
-		netif_wake_queue(skge->netdev);
+	netif_wake_queue(skge->netdev);
 
 	if (netif_msg_link(skge))
 		printk(KERN_INFO PFX
@@ -2190,8 +2189,6 @@ static int skge_up(struct net_device *dev)
 	if (err)
 		goto free_rx_ring;
 
-	skge->tx_avail = skge->tx_ring.count - 1;
-
 	/* Initialize MAC */
 	spin_lock_bh(&hw->phy_lock);
 	if (hw->chip_id == CHIP_ID_GENESIS)
@@ -2294,6 +2291,12 @@ static int skge_down(struct net_device *dev)
 	return 0;
 }
 
+static inline int skge_avail(const struct skge_ring *ring)
+{
+	return ((ring->to_clean > ring->to_use) ? 0 : ring->count)
+		+ (ring->to_clean - ring->to_use) - 1;
+}
+
 static int skge_xmit_frame(struct sk_buff *skb, struct net_device *dev)
 {
 	struct skge_port *skge = netdev_priv(dev);
@@ -2314,7 +2317,7 @@ static int skge_xmit_frame(struct sk_buff *skb, struct net_device *dev)
 		return NETDEV_TX_LOCKED;
 	}
 
-	if (unlikely(skge->tx_avail < skb_shinfo(skb)->nr_frags +1)) {
+	if (unlikely(skge_avail(&skge->tx_ring) < skb_shinfo(skb)->nr_frags + 1)) {
 		if (!netif_queue_stopped(dev)) {
 			netif_stop_queue(dev);
 
@@ -2390,8 +2393,7 @@ static int skge_xmit_frame(struct sk_buff *skb, struct net_device *dev)
 		       dev->name, e - ring->start, skb->len);
 
 	ring->to_use = e->next;
-	skge->tx_avail -= skb_shinfo(skb)->nr_frags + 1;
-	if (skge->tx_avail <= MAX_SKB_FRAGS + 1) {
+	if (skge_avail(&skge->tx_ring) <= MAX_SKB_FRAGS + 1) {
 		pr_debug("%s: transmit queue full\n", dev->name);
 		netif_stop_queue(dev);
 	}
@@ -2416,14 +2418,12 @@ static void skge_tx_complete(struct skge_port *skge, struct skge_element *last)
 		e->skb = NULL;
 		pci_unmap_single(pdev, pci_unmap_addr(e, mapaddr),
 				 skb_headlen(skb), PCI_DMA_TODEVICE);
-		++skge->tx_avail;
 
 		for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
 			e = e->next;
 			pci_unmap_page(pdev, pci_unmap_addr(e, mapaddr),
 				       skb_shinfo(skb)->frags[i].size,
 				       PCI_DMA_TODEVICE);
-			++skge->tx_avail;
 		}
 
 		dev_kfree_skb(skb);
@@ -2688,7 +2688,7 @@ static void skge_tx_done(struct skge_port *skge)
 
 	skge_write8(skge->hw, Q_ADDR(txqaddr[skge->port], Q_CSR), CSR_IRQ_CL_F);
 
-	if (skge->tx_avail > MAX_SKB_FRAGS + 1)
+	if (skge_avail(&skge->tx_ring) > MAX_SKB_FRAGS + 1)
 		netif_wake_queue(skge->netdev);
 
 	spin_unlock(&skge->tx_lock);

drivers/net/skge.h

@@ -2418,7 +2418,6 @@ struct skge_port {
 	int		     port;
 
 	spinlock_t	     tx_lock;
-	u32		     tx_avail;
 	struct skge_ring     tx_ring;
 	struct skge_ring     rx_ring;