nla_put_64bit(9)

📦 version 7.3.1, in nixpkgs unstable

💅 nla_put_64bit(9) — the Kernel API Manual, bestie edition 🎀

Okay so this is nla_put_64bit, from the kernel API manual (yes, that manual — the one your kernel-dev mutuals keep quoting). It's a tiny lil function with one job and it does it beautifully. Let's get into it ✨

🌸 NAME 🌸

nla_put_64bit — add a netlink attribute to a socket buffer and align it 💫

✨ SYNOPSIS ✨

int nla_put_64bit (struct sk_buff *skb , int attrtype , int attrlen ,
       const void *data , int padattr );

That's the whole signature, no cap. Five args, one int coming back at you 🫶

🦋 ARGUMENTS 🦋

  • skb — the socket buffer you're adding the attribute to. It's the canvas, she's the main character 👑
  • attrtype — the attribute type. iykyk 🌈
  • attrlen — length of the attribute payload, fr fr. Measure twice, put once 📏
  • data — head of the attribute payload. Like, the start of it, literally the head 💜
  • padattr — the attribute type used for the padding. Padding has a type and this is it 💅

🔥 DESCRIPTION 🔥

So here's the tea: it returns -EMSGSIZE if the tailroom of the skb is insufficient to store the attribute header and payload 😭 That's it. That's the whole documented behaviour. Not enough tailroom? -EMSGSIZE. Vibe check failed, attribute not added 💀

ngl, that -EMSGSIZE is a real one — if the tailroom can't hold the attribute header and the payload, that's your error. No silent truncation, no "oops", just -EMSGSIZE. Respect, honestly 🙈

🧚 SEE ALSO 🧚

Kernel file ./lib/nlattr.c — and the whole netlink attribute friend group, all iconic, all listed:

That's twenty-one whole functions, bestie. Go read them all, I believe in you 🌟

And that's the page 🎀💖 She lives in ./lib, dated October 2026, and this lil reproduction of nla_put_64bit(9) is officially closed out. Periodt 🫶✨

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