netxen: fix deadlock on dev close

netxen: fix deadlock on dev close

The tx ring accounting fix in commit cb2107be43d2fc5eadec58b92b
("netxen: fix tx ring accounting") introduced intermittent
deadlock when inteface is going down.

This was possibly combined effect of speculative tx pause,
calling netif_tx_lock instead of queue lock and unclean
synchronization with napi which could end up unmasking
interrupt.

Signed-off-by: Dhananjay Phadke <dhananjay@netxen.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/netxen/netxen_nic_hw.c b/drivers/net/netxen/netxen_nic_hw.c
index ce3b89d..b9123d4 100644
--- a/drivers/net/netxen/netxen_nic_hw.c
+++ b/drivers/net/netxen/netxen_nic_hw.c
@@ -461,13 +461,14 @@
 	i = 0;
 
 	tx_ring = adapter->tx_ring;
-	netif_tx_lock_bh(adapter->netdev);
+	__netif_tx_lock_bh(tx_ring->txq);
 
 	producer = tx_ring->producer;
 	consumer = tx_ring->sw_consumer;
 
-	if (nr_desc >= find_diff_among(producer, consumer, tx_ring->num_desc)) {
-		netif_tx_unlock_bh(adapter->netdev);
+	if (nr_desc >= netxen_tx_avail(tx_ring)) {
+		netif_tx_stop_queue(tx_ring->txq);
+		__netif_tx_unlock_bh(tx_ring->txq);
 		return -EBUSY;
 	}
 
@@ -490,7 +491,7 @@
 
 	netxen_nic_update_cmd_producer(adapter, tx_ring);
 
-	netif_tx_unlock_bh(adapter->netdev);
+	__netif_tx_unlock_bh(tx_ring->txq);
 
 	return 0;
 }