net/mlx5e: Fix possible non-initialized struct usage

If mlx5e_devlink_port_register() fails, driver may try to register
devlink health TX and RX reporters on non-registered devlink port.

Instead, create health reporters only if mlx5e_devlink_port_register()
does not fail. And destroy reporters only if devlink_port is registered.

Also, change mlx5e_get_devlink_port() behavior and return NULL in case
port is not registered to replicate devlink's wrapper when ndo is not
implemented.
Signed-off-by: Vladyslav Tarasiuk <vladyslavt@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

drivers/net/ethernet/mellanox/mlx5/core/en/devlink.c

@@ -55,12 +55,17 @@ void mlx5e_devlink_port_unregister(struct mlx5e_priv *priv)
 {
 	struct devlink_port *dl_port = mlx5e_devlink_get_dl_port(priv);
 
+	if (dl_port->registered)
 		devlink_port_unregister(dl_port);
 }
 
 struct devlink_port *mlx5e_get_devlink_port(struct net_device *dev)
 {
 	struct mlx5e_priv *priv = netdev_priv(dev);
+	struct devlink_port *port;
 
-	return mlx5e_devlink_get_dl_port(priv);
+	port = mlx5e_devlink_get_dl_port(priv);
+	if (port->registered)
+		return port;
+	return NULL;
 }

drivers/net/ethernet/mellanox/mlx5/core/en_main.c

@@ -4886,6 +4886,7 @@ static int mlx5e_nic_init(struct mlx5_core_dev *mdev,
 			  struct net_device *netdev)
 {
 	struct mlx5e_priv *priv = netdev_priv(netdev);
+	struct devlink_port *dl_port;
 	int err;
 
 	mlx5e_build_nic_params(priv, &priv->xsk, netdev->mtu);
@@ -4901,6 +4902,8 @@ static int mlx5e_nic_init(struct mlx5_core_dev *mdev,
 	if (err)
 		mlx5_core_err(mdev, "TLS initialization failed, %d\n", err);
 
+	dl_port = mlx5e_devlink_get_dl_port(priv);
+	if (dl_port->registered)
 		mlx5e_health_create_reporters(priv);
 
 	return 0;
@@ -4908,6 +4911,9 @@ static int mlx5e_nic_init(struct mlx5_core_dev *mdev,
 
 static void mlx5e_nic_cleanup(struct mlx5e_priv *priv)
 {
+	struct devlink_port *dl_port = mlx5e_devlink_get_dl_port(priv);
+
+	if (dl_port->registered)
 		mlx5e_health_destroy_reporters(priv);
 	mlx5e_tls_cleanup(priv);
 	mlx5e_ipsec_cleanup(priv);