[TG3]: Fix set ring params tx ring size implementation

Fixes the implementation of the ethtool set ring parameters for the
tg3 transmit ring.  The size of tx_pending is taken into account
before doing a netif_wake_queue.  This prevents the interface from
locking up when smaller transmit ring sizes are used.

Signed-off-by: Ranjit Manomohan <ranjitm@google.com>
Acked-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/tg3.c

@@ -129,7 +129,7 @@
 #define RX_JUMBO_PKT_BUF_SZ	(9046 + tp->rx_offset + 64)
 
 /* minimum number of free TX descriptors required to wake up TX process */
-#define TG3_TX_WAKEUP_THRESH		(TG3_TX_RING_SIZE / 4)
+#define TG3_TX_WAKEUP_THRESH(tp)		((tp)->tx_pending / 4)
 
 /* number of ETHTOOL_GSTATS u64's */
 #define TG3_NUM_STATS		(sizeof(struct tg3_ethtool_stats)/sizeof(u64))
@@ -3075,10 +3075,10 @@ static void tg3_tx(struct tg3 *tp)
 	smp_mb();
 
 	if (unlikely(netif_queue_stopped(tp->dev) &&
-		     (tg3_tx_avail(tp) > TG3_TX_WAKEUP_THRESH))) {
+		     (tg3_tx_avail(tp) > TG3_TX_WAKEUP_THRESH(tp)))) {
 		netif_tx_lock(tp->dev);
 		if (netif_queue_stopped(tp->dev) &&
-		    (tg3_tx_avail(tp) > TG3_TX_WAKEUP_THRESH))
+		    (tg3_tx_avail(tp) > TG3_TX_WAKEUP_THRESH(tp)))
 			netif_wake_queue(tp->dev);
 		netif_tx_unlock(tp->dev);
 	}
@@ -3928,7 +3928,7 @@ static int tg3_start_xmit(struct sk_buff *skb, struct net_device *dev)
 	tp->tx_prod = entry;
 	if (unlikely(tg3_tx_avail(tp) <= (MAX_SKB_FRAGS + 1))) {
 		netif_stop_queue(dev);
-		if (tg3_tx_avail(tp) > TG3_TX_WAKEUP_THRESH)
+		if (tg3_tx_avail(tp) > TG3_TX_WAKEUP_THRESH(tp))
 			netif_wake_queue(tp->dev);
 	}
 
@@ -4143,7 +4143,7 @@ static int tg3_start_xmit_dma_bug(struct sk_buff *skb, struct net_device *dev)
 	tp->tx_prod = entry;
 	if (unlikely(tg3_tx_avail(tp) <= (MAX_SKB_FRAGS + 1))) {
 		netif_stop_queue(dev);
-		if (tg3_tx_avail(tp) > TG3_TX_WAKEUP_THRESH)
+		if (tg3_tx_avail(tp) > TG3_TX_WAKEUP_THRESH(tp))
 			netif_wake_queue(tp->dev);
 	}