In mlx5_ib_alloc_transport_domain(), an early success path was
returning 'err' (which is 0) instead of a literal 0.

Additionally, as identified by Sashiko, if mlx5_ib_enable_lb() fails
at the end of the function, the previously allocated transport domain
(tdn) is leaked because it is never deallocated.

Explicitly return 0 in the early success path and add error handling
to deallocate the transport domain if loopback enablement fails.

Signed-off-by: Prathamesh Deshpande <prathameshdeshpande7@gmail.com>
---
v2:
- Added deallocation of tdn if mlx5_ib_enable_lb() fails [Sashiko].
- Reworded commit message to reflect the functional fix and credit the tool.

Hi Leon,

Thanks for the feedback. I've incorporated the fix for the tdn leak
identified by Sashiko into this v2.

Thanks,
Prathamesh

 drivers/infiniband/hw/mlx5/main.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/infiniband/hw/mlx5/main.c b/drivers/infiniband/hw/mlx5/main.c
index 635002e684a5..c48dd78491eb 100644
--- a/drivers/infiniband/hw/mlx5/main.c
+++ b/drivers/infiniband/hw/mlx5/main.c
@@ -2068,9 +2068,13 @@ static int mlx5_ib_alloc_transport_domain(struct mlx5_ib_dev *dev, u32 *tdn,
 	if ((MLX5_CAP_GEN(dev->mdev, port_type) != MLX5_CAP_PORT_TYPE_ETH) ||
 	    (!MLX5_CAP_GEN(dev->mdev, disable_local_lb_uc) &&
 	     !MLX5_CAP_GEN(dev->mdev, disable_local_lb_mc)))
-		return err;
+		return 0;
 
-	return mlx5_ib_enable_lb(dev, true, false);
+	err = mlx5_ib_enable_lb(dev, true, false);
+	if (err)
+		mlx5_cmd_dealloc_transport_domain(dev->mdev, *tdn, uid);
+
+	return err;
 }
 
 static void mlx5_ib_dealloc_transport_domain(struct mlx5_ib_dev *dev, u32 tdn,
-- 
2.43.0