David Miller [off-list ref] wrote:

vlan: Fix header ops passthru when doing TX VLAN offload.

When the vlan code detects that the real device can do TX VLAN offloads
in hardware, it tries to arrange for the real device's header_ops to
be invoked directly.

Sorry for the late reply.

+static inline int dev_rebuild_header(struct sk_buff *skb)
+{
+	const struct net_device *dev = skb->dev;
+
+	if (!dev->header_ops || !dev->header_ops->rebuild)
+		return 0;
+	return dev->header_ops->rebuild(skb);
+}
+

[..]

+static const struct header_ops vlan_passthru_header_ops = {
+	.create	 = vlan_passthru_hard_header,
+	.rebuild = dev_rebuild_header,

Doesn't that result in infinite recursion when invoking
dev_rebuild_header() on skb whose dev->header_ops is
vlan_passthru_header_ops?