RDMA/mlx5: Annotate lock dependency in bind/unbind slave port

NULL-ing notifier_call is performed under protection
of mlx5_ib_multiport_mutex lock. Such protection is
not easily spotted and better to be guarded by lockdep
annotation.
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Link: https://lore.kernel.org/r/20190813102814.22350-1-leon@kernel.orgSigned-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/hw/mlx5/main.c

@@ -5819,7 +5819,6 @@ static void init_delay_drop(struct mlx5_ib_dev *dev)
 		mlx5_ib_warn(dev, "Failed to init delay drop debugfs\n");
 }
 
-/* The mlx5_ib_multiport_mutex should be held when calling this function */
 static void mlx5_ib_unbind_slave_port(struct mlx5_ib_dev *ibdev,
 				      struct mlx5_ib_multiport_info *mpi)
 {
@@ -5829,6 +5828,8 @@ static void mlx5_ib_unbind_slave_port(struct mlx5_ib_dev *ibdev,
 	int err;
 	int i;
 
+	lockdep_assert_held(&mlx5_ib_multiport_mutex);
+
 	mlx5_ib_cleanup_cong_debugfs(ibdev, port_num);
 
 	spin_lock(&port->mp.mpi_lock);
@@ -5879,13 +5880,14 @@ static void mlx5_ib_unbind_slave_port(struct mlx5_ib_dev *ibdev,
 	ibdev->port[port_num].roce.last_port_state = IB_PORT_DOWN;
 }
 
-/* The mlx5_ib_multiport_mutex should be held when calling this function */
 static bool mlx5_ib_bind_slave_port(struct mlx5_ib_dev *ibdev,
 				    struct mlx5_ib_multiport_info *mpi)
 {
 	u8 port_num = mlx5_core_native_port_num(mpi->mdev) - 1;
 	int err;
 
+	lockdep_assert_held(&mlx5_ib_multiport_mutex);
+
 	spin_lock(&ibdev->port[port_num].mp.mpi_lock);
 	if (ibdev->port[port_num].mp.mpi) {
 		mlx5_ib_dbg(ibdev, "port %d already affiliated.\n",