vlan_insert_tag(9)

📦 version 7.3.1, in nixpkgs unstable

💖 vlan_insert_tag(9) — the Kernel API Manual, bestie edition 💖

okay so this is a page from the Kernel API Manual and it's literally about vlan_insert_tag, which does regular VLAN tag inserting. yes that's the whole name. she's straightforward, she's iconic, she's a kernel function 🎀

✨ SYNOPSIS ✨

struct sk_buff * vlan_insert_tag (struct sk_buff *skb , __be16
vlan_proto , u16 vlan_tci );

like, look at her. three args. no notes. 💅

🌸 ARGUMENTS 🌸

  • skb — the skbuff you're tagging, aka the main character of this whole operation 🫶
  • vlan_proto — the VLAN encapsulation protocol. the vibe of the tag, iykyk
  • vlan_tci — the VLAN TCI you want to insert. yes it's a real thing, yes you need it

🦋 DESCRIPTION 🦋

So what does she do? She inserts the VLAN tag into skb as part of the payload, and returns a VLAN tagged skb back to you. Slay. ✨

Heads up bestie: this might change skb->head. not a drill. 💀

Following the skb_unshare example, in case of error, the calling function doesn't have to worry about freeing the original skb — she handles that whole situation for you, no cap. honestly? queen behaviour. 👑

Also super important: she does not change skb->protocol, which is exactly why this function can be used during receive. that's the whole reason she's built like that, periodt. 🌈

⭐ RETURN ⭐

  • modified skb on success 🎉
  • NULL on error — and yeah, in that case the skb is freed 😭 (she took care of it, remember?)

💜 SEE ALSO 💜

Kernel file ./include/linux/if_vlan.h — go read it, it's giving essential lore 📖

and the whole friend group:

okay that's the whole page bestie, ily, go tag some skbs responsibly 🧚💖

and for the record, this one came out of ./include/linux in October 2026 — so it's basically a vintage. treasure it. 🍓💅

📦 where this page comes from