netdev_alloc_skb(9)

📦 version 7.3.1, in nixpkgs unstable

💖 netdev_alloc_skb — kernel API manual, but make it make sense ✨

okay bestie, welcome to the netdev_alloc_skb(9) page, straight out of the kernel API manual. this one's a little function with a big job and honestly she's iconic for it 🎀

🌸 NAME 🌸

netdev_alloc_skb — allocate an skbuff for rx on a specific device

like, you're grabbing a fresh sk_buff specifically to receive stuff on one particular network device. that's the whole vibe. no cap 💅

🦋 SYNOPSIS 🦋

struct sk_buff * netdev_alloc_skb (struct net_device *dev , unsigned int
length );

copy it exactly, don't be cute with the signature, she is who she is 🫶

✨ ARGUMENTS ✨

  • dev — the network device you're receiving on. your main character interface, basically 👑
  • length — the length to allocate. how much room you're asking for, fr fr

💜 DESCRIPTION 💜

so here's the tea 🍓 — this function allocates a brand new sk_buff and assigns it a usage count of one. that's your starting refcount, periodt.

here's the part that trips people up though: the buffer has unspecified headroom built in. like, unspecified. you don't get to know. 🙈 so if you're a user of this function, you should go ahead and allocate the headroom you think you need — without accounting for that built-in space. the built-in space exists purely for optimisations, so don't go counting it like it's yours, bestie.

and ngl, NULL is returned if there's no free memory. that's your out-of-memory signal, so check for it, okay? 😭

also this is lowkey the coolest part: even though this function allocates memory, it can be called from an interrupt. yeah. she works in interrupt context. slay 🔥

⭐ SEE ALSO ⭐

the whole friend group 🫶 — kernel file ./include/linux/skbuff.h, plus:

that's a lot of links and yes i typed every single one of them, you're welcome 💅 went through them all, no skips, no shortcuts 🧚

💀 real talk though: that unspecified headroom thing is not a suggestion. don't assume built-in space is your space. allocate what you need yourself and let the built-in stuff do its optimisation thing in peace.

🎀 the cute sign-off 🎀

this page lives over in ./include/linux, and she's dated October 2026. anyway ily, go check your NULL returns, and remember: allocate your own headroom, bestie 🌈✨🦋

📦 where this page comes from