skb_copy_and...datagram_msg(9)

💖 skb_copy_and_csum_datagram_msg — Kernel API Manual 💖

okay bestie, welcome to the skb_copy_and...datagram_msg(9) page, like the actual kernel API manual entry for skb_copy_and_csum_datagram_msg. yes the title got truncated with dots, that's just how the man page shows it, we don't fix it, we respect it ✨

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🌸 NAME 🌸

skb_copy_and_csum_datagram_msg — literally does what it says on the tin: copy an skb over to a user iovec and checksum it at the same time. two jobs, one function, main character energy 👑

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✨ SYNOPSIS ✨

int skb_copy_and_csum_datagram_msg (struct sk_buff *skb , int hlen ,
struct msghdr *msg );

that's the whole vibe check right there 🫶 three args, returns an int.

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🎀 ARGUMENTS 🎀

• skb — the skbuff in question, the little packet bb itself 🦋
• hlen — the hardware length, yes that's what it is, don't come for me
• msg — the destination, like where it's all going 🎯

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💅 DESCRIPTION 💅

okay so this is the important part and I need you to lock in: the Caller _must_ check that skb will fit to this iovec. not "should", not "maybe", must. that underscore emphasis is in the original and it's there for a REASON 😭 this is one of those things where if you skip it, that's on you, not on the function 💀

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⭐ RETURN ⭐

• 0 — success, we ate, no notes 💖
• -EINVAL — checksum failure 🙈 something didn't add up (literally)
• -EFAULT — fault during copy 🌧️ the copy went sideways

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🌈 SEE ALSO 🌈

Kernel file ./net/core/datagram.c and honestly the whole friend group:

• __skb_try_recv_datagram(9)
• skb_kill_datagram(9)
• skb_copy_and_crc32c_datagram_iter(9)
• skb_copy_datagram_iter(9)
• skb_copy_datagram_from_iter(9)
• zerocopy_sg_from_iter(9)
• skb_copy_and_csum_datagram(9)
• datagram_poll_queue(9)
• datagram_poll(9)

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not me ending the page but like, go read those too, iykyk 🧚

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and that's the whole thing bestie!! this page lives under ./net/core and it's dated October 2026 in the Kernel API Manual — so yeah, freshly stamped, iconic, periodt 🎀💜🔥