net/mlx5: Bridge, fix peer entry ageing in LAG mode

With current implementation in single FDB LAG mode all packets are
processed by eswitch 0 rules. As such, 'peer' FDB entries receive the
packets for rules of other eswitches and are responsible for updating the
main entry by sending SWITCHDEV_FDB_ADD_TO_BRIDGE notification from their
background update wq task. However, this introduces a race condition when
non-zero eswitch instance decides to delete a FDB entry, sends
SWITCHDEV_FDB_DEL_TO_BRIDGE notification, but another eswitch's update task
refreshes the same entry concurrently while its async delete work is still
pending on the workque. In such case another SWITCHDEV_FDB_ADD_TO_BRIDGE
event may be generated and entry will remain stuck in FDB marked as
'offloaded' since no more SWITCHDEV_FDB_DEL_TO_BRIDGE notifications are
sent for deleting the peer entries.

Fix the issue by synchronously marking deleted entries with
MLX5_ESW_BRIDGE_FLAG_DELETED flag and skipping them in background update
job.
Signed-off-by: Vlad Buslov <vladbu@nvidia.com>
Reviewed-by: Jianbo Liu <jianbol@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

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

@@ -467,6 +467,17 @@ static int mlx5_esw_bridge_switchdev_event(struct notifier_block *nb,
 		/* only handle the event on peers */
 		if (mlx5_esw_bridge_is_local(dev, rep, esw))
 			break;
+
+		fdb_info = container_of(info,
+					struct switchdev_notifier_fdb_info,
+					info);
+		/* Mark for deletion to prevent the update wq task from
+		 * spuriously refreshing the entry which would mark it again as
+		 * offloaded in SW bridge. After this fallthrough to regular
+		 * async delete code.
+		 */
+		mlx5_esw_bridge_fdb_mark_deleted(dev, vport_num, esw_owner_vhca_id, br_offloads,
+						 fdb_info);
 		fallthrough;
 	case SWITCHDEV_FDB_ADD_TO_DEVICE:
 	case SWITCHDEV_FDB_DEL_TO_DEVICE:

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

@@ -1748,6 +1748,28 @@ void mlx5_esw_bridge_fdb_update_used(struct net_device *dev, u16 vport_num, u16
 	entry->lastuse = jiffies;
 }
 
+void mlx5_esw_bridge_fdb_mark_deleted(struct net_device *dev, u16 vport_num, u16 esw_owner_vhca_id,
+				      struct mlx5_esw_bridge_offloads *br_offloads,
+				      struct switchdev_notifier_fdb_info *fdb_info)
+{
+	struct mlx5_esw_bridge_fdb_entry *entry;
+	struct mlx5_esw_bridge *bridge;
+
+	bridge = mlx5_esw_bridge_from_port_lookup(vport_num, esw_owner_vhca_id, br_offloads);
+	if (!bridge)
+		return;
+
+	entry = mlx5_esw_bridge_fdb_lookup(bridge, fdb_info->addr, fdb_info->vid);
+	if (!entry) {
+		esw_debug(br_offloads->esw->dev,
+			  "FDB mark deleted entry with specified key not found (MAC=%pM,vid=%u,vport=%u)\n",
+			  fdb_info->addr, fdb_info->vid, vport_num);
+		return;
+	}
+
+	entry->flags |= MLX5_ESW_BRIDGE_FLAG_DELETED;
+}
+
 void mlx5_esw_bridge_fdb_create(struct net_device *dev, u16 vport_num, u16 esw_owner_vhca_id,
 				struct mlx5_esw_bridge_offloads *br_offloads,
 				struct switchdev_notifier_fdb_info *fdb_info)
@@ -1810,7 +1832,8 @@ void mlx5_esw_bridge_update(struct mlx5_esw_bridge_offloads *br_offloads)
 			unsigned long lastuse =
 				(unsigned long)mlx5_fc_query_lastuse(entry->ingress_counter);
 
-			if (entry->flags & MLX5_ESW_BRIDGE_FLAG_ADDED_BY_USER)
+			if (entry->flags & (MLX5_ESW_BRIDGE_FLAG_ADDED_BY_USER |
+					    MLX5_ESW_BRIDGE_FLAG_DELETED))
 				continue;
 
 			if (time_after(lastuse, entry->lastuse))

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

@@ -62,6 +62,9 @@ int mlx5_esw_bridge_vport_peer_unlink(struct net_device *br_netdev, u16 vport_nu
 void mlx5_esw_bridge_fdb_update_used(struct net_device *dev, u16 vport_num, u16 esw_owner_vhca_id,
 				     struct mlx5_esw_bridge_offloads *br_offloads,
 				     struct switchdev_notifier_fdb_info *fdb_info);
+void mlx5_esw_bridge_fdb_mark_deleted(struct net_device *dev, u16 vport_num, u16 esw_owner_vhca_id,
+				      struct mlx5_esw_bridge_offloads *br_offloads,
+				      struct switchdev_notifier_fdb_info *fdb_info);
 void mlx5_esw_bridge_fdb_create(struct net_device *dev, u16 vport_num, u16 esw_owner_vhca_id,
 				struct mlx5_esw_bridge_offloads *br_offloads,
 				struct switchdev_notifier_fdb_info *fdb_info);

drivers/net/ethernet/mellanox/mlx5/core/esw/bridge_priv.h

@@ -133,6 +133,7 @@ struct mlx5_esw_bridge_mdb_key {
 enum {
 	MLX5_ESW_BRIDGE_FLAG_ADDED_BY_USER = BIT(0),
 	MLX5_ESW_BRIDGE_FLAG_PEER = BIT(1),
+	MLX5_ESW_BRIDGE_FLAG_DELETED = BIT(2),
 };
 
 enum {