qlcnic: fix race in skb->len access.

As soon as skb is given to hardware, TX completion can free skb under us.
Therefore, we should update dev stats before kicking the device.

Signed-off-by: Sucheta Chakraborty <sucheta.chakraborty@qlogic.com>
Signed-off-by: Amit Kumar Salecha <amit.salecha@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/qlcnic/qlcnic_main.c

@@ -2290,11 +2290,11 @@ qlcnic_xmit_frame(struct sk_buff *skb, struct net_device *netdev)
 	if (adapter->mac_learn)
 		qlcnic_send_filter(adapter, tx_ring, first_desc, skb);
 
-	qlcnic_update_cmd_producer(adapter, tx_ring);
-
 	adapter->stats.txbytes += skb->len;
 	adapter->stats.xmitcalled++;
 
+	qlcnic_update_cmd_producer(adapter, tx_ring);
+
 	return NETDEV_TX_OK;
 
 unwind_buff: