[PATCH] net/mlx5e: TC, fix internal port leak when a flow is reoffloaded

[Wentao Liang <vulab@iscas.ac.cn>]

For a flow originating from an OVS internal port,
mlx5e_tc_add_fdb_flow() takes a reference on the internal port and stores
it in the flow's esw attribute.

If the flow cannot be offloaded because the encap route is not available
(-ENETUNREACH) on a multipath LAG setup, __mlx5e_add_fdb_flow() keeps the
flow on the unready list instead of freeing it. When
mlx5e_tc_reoffload_flows_work() retries, mlx5e_tc_add_fdb_flow() takes
another reference and overwrites the stored pointer, so the previous
reference is never dropped.

Only look up the internal port if the flow does not hold a reference
already; the reference is released together with the flow attributes.

Fixes: 166f431ec6be ("net/mlx5e: Add indirect tc offload of ovs internal port")
Cc: stable@vger.kernel.org
Assisted-by: DeepSeek-V4.1-Flash and OpenAI Codex
Signed-off-by: Wentao Liang <vulab@iscas.ac.cn>
---
 .../net/ethernet/mellanox/mlx5/core/en_tc.c   | 22 ++++++++++---------
 1 file changed, 12 insertions(+), 10 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c b/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
index 17bd92529a44..8246378b089f 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
@@ -2005,17 +2005,19 @@ mlx5e_tc_add_fdb_flow(struct mlx5e_priv *priv,
 			goto err_out;
 		}
 
-		int_port = mlx5e_tc_int_port_get(mlx5e_get_int_port_priv(priv),
-						 parse_attr->filter_dev->ifindex,
-						 flow_flag_test(flow, EGRESS) ?
-						 MLX5E_TC_INT_PORT_EGRESS :
-						 MLX5E_TC_INT_PORT_INGRESS);
-		if (IS_ERR(int_port)) {
-			err = PTR_ERR(int_port);
-			goto err_out;
-		}
+		if (!esw_attr->int_port) {
+			int_port = mlx5e_tc_int_port_get(mlx5e_get_int_port_priv(priv),
+							 parse_attr->filter_dev->ifindex,
+							 flow_flag_test(flow, EGRESS) ?
+							 MLX5E_TC_INT_PORT_EGRESS :
+							 MLX5E_TC_INT_PORT_INGRESS);
+			if (IS_ERR(int_port)) {
+				err = PTR_ERR(int_port);
+				goto err_out;
+			}
 
-		esw_attr->int_port = int_port;
+			esw_attr->int_port = int_port;
+		}
 	}
 
 	err = post_process_attr(flow, attr, extack);
-- 
2.34.1