__skb_get_hash_net(9)

💖 __skb_get_hash_net — NAME 💖

Okay so bestie, this is __skb_get_hash_net — the kernel function that literally calculates a flow hash. That's the whole vibe. ✨

It lives in the Kernel API Manual, section 9, iykyk.

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🌸 SYNOPSIS 🌸

void __skb_get_hash_net (const struct net *net , struct sk_buff *skb );

That's it. Two args, returns nothing. Void. No notes, no receipts, just vibes and a hash. 🎀

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🦋 ARGUMENTS 🦋

• net — the associated network namespace, and here's the cute part: if it's NULL, it gets derived from skb. So like, you can be lazy about it, no judgment. 🙈
• skb — the sk_buff we're calculating the flow hash from. This is the main character right here. 👑

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⭐ DESCRIPTION ⭐

So what does it actually do, you ask? 🫶

This function calculates a flow hash based on the src/dst addresses and the src/dst port numbers. Classic 4-tuple situation. It's giving very "know your traffic" energy.

On success it sets the hash in skb to a non-zero hash value — and heads up, zero means there's no valid hash, so if you see a zero, don't celebrate, that's the "nope" state. 💀

It also sets l4_hash in skb if the hash is a canonical 4-tuple hash over transport ports. Which, like, is a whole specific situation, but when it applies it applies. ✨

Lowkey important: non-zero = success, zero = no valid hash. Fr fr, don't mix those up. 🎀

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🔥 SEE ALSO 🔥

Go check these out, they're all in the same friend group:

• Kernel file ./net/core/flow_dissector.c
• skb_flow_get_ports(9)
• skb_flow_get_icmp_tci(9)
• __skb_flow_dissect_batadv(9)
• __skb_flow_dissect(9)
• skb_get_poff(9)

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🌈 CUTE SIGN-OFF 🌈

That's the page, bestie! 🧚 This one's from ./net/core, dated October 2026, sitting pretty in the Kernel API Manual — __skb_get_hash_net(9), periodt. 💅💜 Go hash something iconic. 🦋🌸