skb_copy_expand(9)

📦 version 7.3.1, in nixpkgs unstable

💅 skb_copy_expand — copy and expand sk_buff

okay bestie, welcome to skb_copy_expand(9) from the Kernel API Manual ✨ this is a kernel-networking girly and she is very good at her job, so let's get into it 🫶

🎀 SYNOPSIS 🎀

struct sk_buff * skb_copy_expand (const struct sk_buff *skb , int
newheadroom , int newtailroom , gfp_t gfp_mask );

like, that's the whole signature, no notes 💅

🌸 ARGUMENTS 🌸

  • skb — the buffer you wanna copy, bestie. your source material 👑
  • newheadroom — how many new free bytes you want at the head 🎀
  • newtailroom — how many new free bytes you want at the tail 🦋
  • gfp_mask — the allocation priority. yes it matters, keep reading 😭

✨ DESCRIPTION ✨

So what this does is: it makes a copy of an sk_buff and its data, and while it's doing that it also allocates extra space for you 💖 literally copying and expanding at the same time, main character energy fr fr.

This is the one you reach for when the caller wants to modify the data and needs a private copy of that data to alter, plus more room for new fields. It returns NULL on failure, or a pointer to the buffer on success. And heads up — the returned buffer has a reference count of 1. ⭐

🚨 ngl this part is important: you must pass GFP_ATOMIC as the allocation priority if this function is called from an interrupt. no cap, don't skip that.

🔥 SEE ALSO 🔥

Kernel file ./net/core/skbuff.c — and like, the whole extended friend group 💀 mwah, enjoy the roster:

okay that's the whole thing, you're so welcome 🧚💜 this page lives over in ./net/core and it's dated October 2026 — go forth and copy those skbs responsibly, bestie. slay 💅✨

📦 where this page comes from