net/mlx5: Bridge, take rtnl lock in init error handler

The mlx5_esw_bridge_cleanup() is expected to be called with rtnl lock
taken, which is true for mlx5e_rep_bridge_cleanup() function but not for
error handling code in mlx5e_rep_bridge_init(). Add missing rtnl
lock/unlock calls and extend both mlx5_esw_bridge_cleanup() and its dual
function mlx5_esw_bridge_init() with ASSERT_RTNL() to verify the invariant
from now on.

Fixes: 7cd6a54 ("net/mlx5: Bridge, handle FDB events")
Fixes: 19e9bfa ("net/mlx5: Bridge, add offload infrastructure")
Signed-off-by: Vlad Buslov <vladbu@nvidia.com>
Reviewed-by: Roi Dayan <roid@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

drivers/net/ethernet/mellanox/mlx5/core/en/rep/bridge.c

@@ -509,7 +509,9 @@ void mlx5e_rep_bridge_init(struct mlx5e_priv *priv)
 err_register_swdev:
 	destroy_workqueue(br_offloads->wq);
 err_alloc_wq:
+	rtnl_lock();
 	mlx5_esw_bridge_cleanup(esw);
+	rtnl_unlock();
 }
 
 void mlx5e_rep_bridge_cleanup(struct mlx5e_priv *priv)

drivers/net/ethernet/mellanox/mlx5/core/esw/bridge.c

@@ -1574,6 +1574,8 @@ struct mlx5_esw_bridge_offloads *mlx5_esw_bridge_init(struct mlx5_eswitch *esw)
 {
 	struct mlx5_esw_bridge_offloads *br_offloads;
 
+	ASSERT_RTNL();
+
 	br_offloads = kvzalloc(sizeof(*br_offloads), GFP_KERNEL);
 	if (!br_offloads)
 		return ERR_PTR(-ENOMEM);
@@ -1590,6 +1592,8 @@ void mlx5_esw_bridge_cleanup(struct mlx5_eswitch *esw)
 {
 	struct mlx5_esw_bridge_offloads *br_offloads = esw->br_offloads;
 
+	ASSERT_RTNL();
+
 	if (!br_offloads)
 		return;