[PATCH net v2 2/3] net/mlx5: LAG, check if vport exists on br_offloads

[Bernardo Soares <bsoares.it@gmail.com>]

mlx5_esw_bridge_lower_rep_vport_num_vhca_id_get() walks a LAG bond's
lower devices and returns the first rep that's structurally eligible
(same HCA, is a rep), without checking it's tracked by the calling
instance's br_offloads. On a merged-eswitch HCA where a bond spans
reps of more than one eswitch instance, this can return a sibling's
rep instead of continuing to the one this instance actually owns -
reached via mlx5_esw_bridge_port_obj_attr_set(), so a bridge attribute
change on a bonded uplink can silently no-op on the right instance.
Fix by checking mlx5_esw_bridge_port_exists() at the point each rep is
picked, same as the previous commit did for the single-rep case.

Signed-off-by: Bernardo Soares <bersoare@isovalent.com>
---
v2: new patch, addresses review comment on v1 asking whether
    mlx5_esw_bridge_lower_rep_vport_num_vhca_id_get() should verify
    the rep it picks while walking a LAG bond's lower devices is
    actually tracked by the calling instance's br_offloads, since it
    otherwise returns on the first structurally-eligible rep found,
    which is not necessarily the one owned by this eswitch instance.
---

 .../net/ethernet/mellanox/mlx5/core/en/rep/bridge.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/rep/bridge.c b/drivers/net/ethernet/mellanox/mlx5/core/en/rep/bridge.c
index 56592e2e6b9b..4b7b0a0fc2b2 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en/rep/bridge.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en/rep/bridge.c
@@ -85,9 +85,16 @@ mlx5_esw_bridge_lower_rep_vport_num_vhca_id_get(struct net_device *dev, struct m
 	struct net_device *lower_dev;
 	struct list_head *iter;
 
-	if (netif_is_lag_master(dev) || mlx5e_eswitch_rep(dev))
-		return mlx5_esw_bridge_rep_vport_num_vhca_id_get(dev, esw, vport_num,
-								 esw_owner_vhca_id);
+	if (netif_is_lag_master(dev) || mlx5e_eswitch_rep(dev)) {
+		struct net_device *rep;
+
+		rep = mlx5_esw_bridge_rep_vport_num_vhca_id_get(dev, esw, vport_num,
+								esw_owner_vhca_id);
+		if (rep && !mlx5_esw_bridge_port_exists(*vport_num, *esw_owner_vhca_id,
+							esw->br_offloads))
+			return NULL;
+		return rep;
+	}
 
 	netdev_for_each_lower_dev(dev, lower_dev, iter) {
 		struct net_device *rep;
-- 
2.43.0