netxen: Fix BUG "sleeping function called from invalid context"

o __netxen_nic_down() function might sleep while holding spinlock_t(tx_clean_lock).
  Acquire this lock for only releasing TX buffers instead of taking it
  for whole down path.
Reported-by: Mike Galbraith <umgwanakikbuti@gmail.com>
Signed-off-by: Manish Chopra <manish.chopra@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/qlogic/netxen/netxen_nic_init.c

@@ -135,6 +135,7 @@ void netxen_release_tx_buffers(struct netxen_adapter *adapter)
 	int i, j;
 	struct nx_host_tx_ring *tx_ring = adapter->tx_ring;
 
+	spin_lock(&adapter->tx_clean_lock);
 	cmd_buf = tx_ring->cmd_buf_arr;
 	for (i = 0; i < tx_ring->num_desc; i++) {
 		buffrag = cmd_buf->frag_array;
@@ -158,6 +159,7 @@ void netxen_release_tx_buffers(struct netxen_adapter *adapter)
 		}
 		cmd_buf++;
 	}
+	spin_unlock(&adapter->tx_clean_lock);
 }
 
 void netxen_free_sw_resources(struct netxen_adapter *adapter)

drivers/net/ethernet/qlogic/netxen/netxen_nic_main.c

@@ -1186,7 +1186,6 @@ __netxen_nic_down(struct netxen_adapter *adapter, struct net_device *netdev)
 		return;
 
 	smp_mb();
-	spin_lock(&adapter->tx_clean_lock);
 	netif_carrier_off(netdev);
 	netif_tx_disable(netdev);
 
@@ -1204,7 +1203,6 @@ __netxen_nic_down(struct netxen_adapter *adapter, struct net_device *netdev)
 	netxen_napi_disable(adapter);
 
 	netxen_release_tx_buffers(adapter);
-	spin_unlock(&adapter->tx_clean_lock);
 }
 
 /* Usage: During suspend and firmware recovery module */