IB/mlx4: Move rtnl locking to the right place

On the one hand, the invocation of netdev_master_upper_dev_get()
within mlx4_ib_scan_netdevs() must be done with rtnl lock held.  On
the other hand, it's wrong to call rtnl_lock() from within this
function since it's also called by our netdev notifier callback.
Therefore move the locking to mlx4_ib_add() so that both cases are
covered.
Signed-off-by: Moni Shoua <monis@mellanox.co.il>
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>

drivers/infiniband/hw/mlx4/main.c

@@ -1707,10 +1707,8 @@ static void mlx4_ib_scan_netdevs(struct mlx4_ib_dev *ibdev)
 						iboe->netdevs[port - 1], port);
 		if (iboe->netdevs[port - 1] &&
 		    netif_is_bond_slave(iboe->netdevs[port - 1])) {
-			rtnl_lock();
 			iboe->masters[port - 1] = netdev_master_upper_dev_get(
 				iboe->netdevs[port - 1]);
-			rtnl_unlock();
 		}
 		curr_master = iboe->masters[port - 1];
 
@@ -2100,7 +2098,9 @@ static void *mlx4_ib_add(struct mlx4_dev *dev)
 			}
 		}
 #endif
+		rtnl_lock();
 		mlx4_ib_scan_netdevs(ibdev);
+		rtnl_unlock();
 		mlx4_ib_init_gid_table(ibdev);
 	}