net: add netif_inherit_tso_max()

To make later patches smaller create a helper for inheriting
the TSO limitations of a lower device. The TSO in the name
is not an accident, subsequent patches will replace GSO
with TSO in more names.

Signed-off-by: Jakub Kicinski <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/ethernet/netronome/nfp/nfp_net_repr.c

···
 	if (repr->dst->u.port_info.lower_dev != lower)
 		return;
 
-	netif_set_gso_max_size(netdev, lower->gso_max_size);
-	netif_set_gso_max_segs(netdev, lower->gso_max_segs);
+	netif_inherit_tso_max(netdev, lower);
 
 	netdev_update_features(netdev);
 }

drivers/net/ipvlan/ipvlan_main.c

···
 	dev->vlan_features = phy_dev->vlan_features & IPVLAN_FEATURES;
 	dev->vlan_features |= IPVLAN_ALWAYS_ON_OFLOADS;
 	dev->hw_enc_features |= dev->features;
-	netif_set_gso_max_size(dev, phy_dev->gso_max_size);
-	netif_set_gso_max_segs(dev, phy_dev->gso_max_segs);
+	netif_inherit_tso_max(dev, phy_dev);
 	dev->hard_header_len = phy_dev->hard_header_len;
 
 	netdev_lockdep_set_classes(dev);
···
 
 	case NETDEV_FEAT_CHANGE:
 		list_for_each_entry(ipvlan, &port->ipvlans, pnode) {
-			netif_set_gso_max_size(ipvlan->dev, dev->gso_max_size);
-			netif_set_gso_max_segs(ipvlan->dev, dev->gso_max_segs);
+			netif_inherit_tso_max(ipvlan->dev, dev);
 			netdev_update_features(ipvlan->dev);
 		}
 		break;

drivers/net/macvlan.c

···
 	dev->vlan_features	= lowerdev->vlan_features & MACVLAN_FEATURES;
 	dev->vlan_features	|= ALWAYS_ON_OFFLOADS;
 	dev->hw_enc_features    |= dev->features;
-	netif_set_gso_max_size(dev, lowerdev->gso_max_size);
-	netif_set_gso_max_segs(dev, lowerdev->gso_max_segs);
+	netif_inherit_tso_max(dev, lowerdev);
 	dev->hard_header_len	= lowerdev->hard_header_len;
 	macvlan_set_lockdep_class(dev);
 
···
 		break;
 	case NETDEV_FEAT_CHANGE:
 		list_for_each_entry(vlan, &port->vlans, list) {
-			netif_set_gso_max_size(vlan->dev, dev->gso_max_size);
-			netif_set_gso_max_segs(vlan->dev, dev->gso_max_segs);
+			netif_inherit_tso_max(vlan->dev, dev);
 			netdev_update_features(vlan->dev);
 		}
 		break;

drivers/net/veth.c

···
 	if (ifmp && (dev->ifindex != 0))
 		peer->ifindex = ifmp->ifi_index;
 
-	netif_set_gso_max_size(peer, dev->gso_max_size);
-	netif_set_gso_max_segs(peer, dev->gso_max_segs);
+	netif_inherit_tso_max(peer, dev);
 
 	err = register_netdevice(peer);
 	put_net(net);

drivers/net/vxlan/vxlan_core.c

···
 	if (lowerdev) {
 		dst->remote_ifindex = conf->remote_ifindex;
 
-		netif_set_gso_max_size(dev, lowerdev->gso_max_size);
-		netif_set_gso_max_segs(dev, lowerdev->gso_max_segs);
+		netif_inherit_tso_max(dev, lowerdev);
 
 		needed_headroom = lowerdev->hard_header_len;
 		needed_headroom += lowerdev->needed_headroom;

include/linux/netdevice.h

···
 	WRITE_ONCE(dev->gro_max_size, size);
 }
 
+void netif_inherit_tso_max(struct net_device *to,
+			   const struct net_device *from);
+
 static inline void skb_gso_error_unwind(struct sk_buff *skb, __be16 protocol,
 					int pulled_hlen, u16 mac_offset,
 					int mac_len)

net/8021q/vlan.c

···
 {
 	struct vlan_dev_priv *vlan = vlan_dev_priv(vlandev);
 
-	netif_set_gso_max_size(vlandev, dev->gso_max_size);
-	netif_set_gso_max_segs(vlandev, dev->gso_max_segs);
+	netif_inherit_tso_max(vlandev, dev);
 
 	if (vlan_hw_offload_capable(dev->features, vlan->vlan_proto))
 		vlandev->hard_header_len = dev->hard_header_len;

net/8021q/vlan_dev.c

···
 			   NETIF_F_ALL_FCOE;
 
 	dev->features |= dev->hw_features | NETIF_F_LLTX;
-	netif_set_gso_max_size(dev, real_dev->gso_max_size);
-	netif_set_gso_max_segs(dev, real_dev->gso_max_segs);
+	netif_inherit_tso_max(dev, real_dev);
 	if (dev->features & NETIF_F_VLAN_FEATURES)
 		netdev_warn(real_dev, "VLAN features are set incorrectly.  Q-in-Q configurations may not work correctly.\n");
 

net/core/dev.c

···
 EXPORT_SYMBOL(netif_set_real_num_queues);
 
 /**
+ * netif_inherit_tso_max() - copy all TSO limits from a lower device to an upper
+ * @to:		netdev to update
+ * @from:	netdev from which to copy the limits
+ */
+void netif_inherit_tso_max(struct net_device *to, const struct net_device *from)
+{
+	netif_set_gso_max_size(to, from->gso_max_size);
+	netif_set_gso_max_segs(to, from->gso_max_segs);
+}
+EXPORT_SYMBOL(netif_inherit_tso_max);
+
+/**
  * netif_get_num_default_rss_queues - default number of RSS queues
  *
  * Default value is the number of physical cores if there are only 1 or 2, or