vxge: don't drop frame on tx queue full

The vxge driver will drop a packet in its transmit function if the number
of TxDs available hits 0.  Instead of doing that, simply stop the transmit
queue when transmitting a packet with the last available TxD.

Signed-off-by: Benjamin LaHaise <ben.lahaise@neterion.com>
Signed-off-by: Sreenivasa Honnur <sreenivasa.honnur@neterion.com>
Signed-off-by: Ramkrishna Vepa <ram.vepa@neterion.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/vxge/vxge-main.c

@@ -895,6 +895,12 @@ vxge_xmit(struct sk_buff *skb, struct net_device *dev)
 		goto _exit2;
 	}
 
+	/* Last TXD?  Stop tx queue to avoid dropping packets.  TX
+	 * completion will resume the queue.
+	 */
+	if (avail == 1)
+		vxge_stop_tx_queue(fifo);
+
 	status = vxge_hw_fifo_txdl_reserve(fifo_hw, &dtr, &dtr_priv);
 	if (unlikely(status != VXGE_HW_OK)) {
 		vxge_debug_tx(VXGE_ERR,