net/mlx5: Bridge, verify LAG state when adding bond to bridge

Mlx5 LAG is initialized asynchronously on a workqueue which means that for
a brief moment after setting mlx5 UL representors as lower devices of a
bond netdevice the LAG itself is not fully initialized in the driver. When
adding such bond device to a bridge mlx5 bridge code will not consider it
as offload-capable, skip creating necessary bookkeeping and fail any
further bridge offload-related commands with it (setting VLANs, offloading
FDBs, etc.). In order to make the error explicit during bridge
initialization stage implement the code that detects such condition during
NETDEV_PRECHANGEUPPER event and returns an error.

Fixes: ff9b7521 ("net/mlx5: Bridge, support LAG")
Signed-off-by: Vlad Buslov <vladbu@nvidia.com>
Reviewed-by: Roi Dayan <roid@nvidia.com>
Reviewed-by: Mark Bloch <mbloch@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

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

@@ -164,6 +164,36 @@ static int mlx5_esw_bridge_port_changeupper(struct notifier_block *nb, void *ptr
 	return err;
 }
 
+static int
+mlx5_esw_bridge_changeupper_validate_netdev(void *ptr)
+{
+	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
+	struct netdev_notifier_changeupper_info *info = ptr;
+	struct net_device *upper = info->upper_dev;
+	struct net_device *lower;
+	struct list_head *iter;
+
+	if (!netif_is_bridge_master(upper) || !netif_is_lag_master(dev))
+		return 0;
+
+	netdev_for_each_lower_dev(dev, lower, iter) {
+		struct mlx5_core_dev *mdev;
+		struct mlx5e_priv *priv;
+
+		if (!mlx5e_eswitch_rep(lower))
+			continue;
+
+		priv = netdev_priv(lower);
+		mdev = priv->mdev;
+		if (!mlx5_lag_is_active(mdev))
+			return -EAGAIN;
+		if (!mlx5_lag_is_shared_fdb(mdev))
+			return -EOPNOTSUPP;
+	}
+
+	return 0;
+}
+
 static int mlx5_esw_bridge_switchdev_port_event(struct notifier_block *nb,
 						unsigned long event, void *ptr)
 {
@@ -171,6 +201,7 @@ static int mlx5_esw_bridge_switchdev_port_event(struct notifier_block *nb,
 
 	switch (event) {
 	case NETDEV_PRECHANGEUPPER:
+		err = mlx5_esw_bridge_changeupper_validate_netdev(ptr);
 		break;
 
 	case NETDEV_CHANGEUPPER: