inet_lookup_reuseport(9)

💅 inet_lookup_reuseport(9) 💅

Okay so bestie, welcome to the inet_lookup_reuseport page from the Kernel API Manual — this is the one that handles the reuseport logic on an AF_INET socket if it's necessary. Like, only if it needs to. Not out here doing extra work for no reason. ✨

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🌸 SYNOPSIS 🌸

struct sock * inet_lookup_reuseport (const struct net *net , struct sock
*sk , struct sk_buff *skb , int doff , __be32 saddr , __be16 sport ,
__be32 daddr , unsigned short hnum , inet_ehashfn_t *ehashfn );

Yeah, it's a whole long signature. Nine arguments. She's got a lot going on but she's iconic for it. 🎀

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🦋 ARGUMENTS 🦋

• net — the network namespace. the whole vibe container basically.
• sk — the AF_INET socket. Heads up though: it must be in TCP_LISTEN state for TCP, or TCP_CLOSE for UDP. Non-negotiable, bestie. 👑
• skb — the context for a potential SK_REUSEPORT program.
• doff — the header offset.
• saddr — source address.
• sport — source port.
• daddr — destination address.
• hnum — destination port, but in host byte order. yes that matters. 🙈
• ehashfn — the hash function used to generate the fallback hash. the backup plan, the understudy, the fallback queen. 💜

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⭐ RETURN ⭐

So what does she give you back?

• NULL — if sk doesn't have SO_REUSEPORT set. like, no reuseport, no results, sorry babe 😭
• otherwise — a pointer to the selected sock, or an error. that's the range. that's the answer. 🔥

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ngl this one's short but she's important, so don't sleep on the state requirements for sk. that TCP_LISTEN / TCP_CLOSE thing is a real vibe check. 💀

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🧚 SEE ALSO 🧚

Kernel file ./net/ipv4/inet_hashtables.c — go read her, she's serving the actual source realness. 🫶

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kisses and good vibes from ./net/ipv4 — that's the source directory, and the date stamp says October 2026 💖 mwah, go slay your socket lookups 🦋✨