macsec: inherit lower device's TSO limits when offloading

If macsec is offloaded, we need to follow the lower device's
capabilities, like VLAN devices do.

Leave the limits unchanged when the offload is disabled.

Signed-off-by: Sabrina Dubroca <[e-mail]>
Reviewed-by: Simon Horman <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

drivers/net/macsec.c

···
 	dev->needed_tailroom = real_dev->needed_tailroom + needed_tailroom;
 }
 
+static void macsec_inherit_tso_max(struct net_device *dev)
+{
+	struct macsec_dev *macsec = macsec_priv(dev);
+
+	/* if macsec is offloaded, we need to follow the lower
+	 * device's capabilities. otherwise, we can ignore them.
+	 */
+	if (macsec_is_offloaded(macsec))
+		netif_inherit_tso_max(dev, macsec->real_dev);
+}
+
 static int macsec_update_offload(struct net_device *dev, enum macsec_offload offload)
 {
 	enum macsec_offload prev_offload;
···
 
 	macsec_set_head_tail_room(dev);
 	macsec->insert_tx_tag = macsec_needs_tx_tag(macsec, ops);
+
+	macsec_inherit_tso_max(dev);
 
 	netdev_update_features(dev);
 
···
 	err = gro_cells_init(&macsec->gro_cells, dev);
 	if (err)
 		return err;
+
+	macsec_inherit_tso_max(dev);
 
 	dev->hw_features = real_dev->hw_features & MACSEC_OFFLOAD_FEATURES;
 	dev->hw_features |= NETIF_F_GSO_SOFTWARE;
···
 			if (dev->mtu > mtu)
 				dev_set_mtu(dev, mtu);
 		}
+		break;
+	case NETDEV_FEAT_CHANGE:
+		list_for_each_entry(m, &rxd->secys, secys) {
+			macsec_inherit_tso_max(m->secy.netdev);
+			netdev_update_features(m->secy.netdev);
+		}
+		break;
 	}
 
 	return NOTIFY_OK;