llc_fixup_skb(9)

💅 llc_fixup_skb — kernel API manual, section 9 ✨

ok so bestie, welcome to llc_fixup_skb(9) — yes that's the manual page name AND the section number, we love a two-for-one. this is your girl's guide to the little helper that gets your skb pointers all sorted before the real work starts 🎀

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🌸 NAME 🌸

llc_fixup_skb — literally just initializes skb pointers. that's it. that's the whole vibe 💖

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🦋 SYNOPSIS 🦋

int llc_fixup_skb (struct sk_buff *skb );

copy it exactly, no cap — the spacing is canon 👑

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✨ ARGUMENTS ✨

• skb — this argument points to the incoming skb. that's the packet sliding into your DMs, bestie 🫶

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💅 DESCRIPTION 💅

okay so here's what she does. she initializes the internal skb pointer to the start of the network layer, and the way she gets there is by deriving the length of the LLC header 🔥

then she finds the length of the LLC control field in that LLC header by looking at the two lowest-order bits of the first control field byte 👀 yes, just the two little bits at the bottom doing all the work. icon behavior.

that field is either 3 or 4 bytes long. periodt. no other options, those are the numbers 💀

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🌈 SEE ALSO 🌈

• Kernel file ./net/llc/llc_input.c
• llc_pdu_type(9)
• llc_rcv(9)

go read those next, iykyk 📚✨

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ngl this page lives in ./net/llc and it's dated October 2026 — so future-you is gonna be reading this and honestly? she ate 💜

stay slay, keep your pointers initialized, mwah 🧚💖