mlxsw: spectrum: handle NETIF_F_HW_TC changes correctly

Currently, whenever the NETIF_F_HW_TC feature changes, we silently
always allow it, but we actually do not disable the flows in HW
on disable. That breaks user's expectations. So just forbid
the feature disable in case there are any filters offloaded.

Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Reviewed-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlxsw/spectrum.c

@@ -1835,6 +1835,54 @@ static int mlxsw_sp_setup_tc(struct net_device *dev, enum tc_setup_type type,
 	}
 }
 
+
+static int mlxsw_sp_feature_hw_tc(struct net_device *dev, bool enable)
+{
+	struct mlxsw_sp_port *mlxsw_sp_port = netdev_priv(dev);
+
+	if (!enable && (mlxsw_sp_port->acl_rule_count ||
+			!list_empty(&mlxsw_sp_port->mall_tc_list))) {
+		netdev_err(dev, "Active offloaded tc filters, can't turn hw_tc_offload off\n");
+		return -EINVAL;
+	}
+	return 0;
+}
+
+typedef int (*mlxsw_sp_feature_handler)(struct net_device *dev, bool enable);
+
+static int mlxsw_sp_handle_feature(struct net_device *dev,
+				   netdev_features_t wanted_features,
+				   netdev_features_t feature,
+				   mlxsw_sp_feature_handler feature_handler)
+{
+	netdev_features_t changes = wanted_features ^ dev->features;
+	bool enable = !!(wanted_features & feature);
+	int err;
+
+	if (!(changes & feature))
+		return 0;
+
+	err = feature_handler(dev, enable);
+	if (err) {
+		netdev_err(dev, "%s feature %pNF failed, err %d\n",
+			   enable ? "Enable" : "Disable", &feature, err);
+		return err;
+	}
+
+	if (enable)
+		dev->features |= feature;
+	else
+		dev->features &= ~feature;
+
+	return 0;
+}
+static int mlxsw_sp_set_features(struct net_device *dev,
+				 netdev_features_t features)
+{
+	return mlxsw_sp_handle_feature(dev, features, NETIF_F_HW_TC,
+				       mlxsw_sp_feature_hw_tc);
+}
+
 static const struct net_device_ops mlxsw_sp_port_netdev_ops = {
 	.ndo_open		= mlxsw_sp_port_open,
 	.ndo_stop		= mlxsw_sp_port_stop,
@@ -1849,6 +1897,7 @@ static const struct net_device_ops mlxsw_sp_port_netdev_ops = {
 	.ndo_vlan_rx_add_vid	= mlxsw_sp_port_add_vid,
 	.ndo_vlan_rx_kill_vid	= mlxsw_sp_port_kill_vid,
 	.ndo_get_phys_port_name	= mlxsw_sp_port_get_phys_port_name,
+	.ndo_set_features	= mlxsw_sp_set_features,
 };
 
 static void mlxsw_sp_port_get_drvinfo(struct net_device *dev,

drivers/net/ethernet/mellanox/mlxsw/spectrum.h

@@ -270,6 +270,7 @@ struct mlxsw_sp_port {
 	struct mlxsw_sp_port_sample *sample;
 	struct list_head vlans_list;
 	struct mlxsw_sp_qdisc root_qdisc;
+	unsigned acl_rule_count;
 };
 
 static inline bool

drivers/net/ethernet/mellanox/mlxsw/spectrum_flower.c

@@ -423,6 +423,7 @@ int mlxsw_sp_flower_replace(struct mlxsw_sp_port *mlxsw_sp_port, bool ingress,
 		goto err_rule_add;
 
 	mlxsw_sp_acl_ruleset_put(mlxsw_sp, ruleset);
+	mlxsw_sp_port->acl_rule_count++;
 	return 0;
 
 err_rule_add:
@@ -454,6 +455,7 @@ void mlxsw_sp_flower_destroy(struct mlxsw_sp_port *mlxsw_sp_port, bool ingress,
 	}
 
 	mlxsw_sp_acl_ruleset_put(mlxsw_sp, ruleset);
+	mlxsw_sp_port->acl_rule_count--;
 }
 
 int mlxsw_sp_flower_stats(struct mlxsw_sp_port *mlxsw_sp_port, bool ingress,