ldmvsw: unregistering netdev before disable hardware

When running LDom binding/unbinding test, kernel may panic
in ldmvsw_open(). It is more likely that because we're removing
the ldc connection before unregistering the netdev in vsw_port_remove(),
we set up a window of time where one process could be removing the
device while another trying to UP the device. This also sometimes causes
vio handshake error due to opening a device without closing it completely.
We should unregister the netdev before we disable the "hardware".

Orabug: 25980913, 25925306

Signed-off-by: Thomas Tai <thomas.tai@oracle.com>
Signed-off-by: Shannon Nelson <shannon.nelson@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/sun/ldmvsw.c

@@ -413,6 +413,7 @@ static int vsw_port_remove(struct vio_dev *vdev)
 		del_timer_sync(&port->vio.timer);
 
 		napi_disable(&port->napi);
+		unregister_netdev(port->dev);
 
 		list_del_rcu(&port->list);
 
@@ -427,7 +428,6 @@ static int vsw_port_remove(struct vio_dev *vdev)
 
 		dev_set_drvdata(&vdev->dev, NULL);
 
-		unregister_netdev(port->dev);
 		free_netdev(port->dev);
 	}