list_first_or_null_rcu(9)

📦 version 7.3.1, in nixpkgs unstable

✨ list_first_or_null_rcu — get the first element from a list ✨

okay so we're in the Kernel API Manual bestie, and this page is about list_first_or_null_rcu(9) — yes that whole mouthful, i promise it's actually so useful 🫶

💖 NAME 💖

list_first_or_null_rcu — get the first element from a list 🌸

🦋 SYNOPSIS 🦋

list_first_or_null_rcu (ptr , type , member );

that's it. three little args. look at her go 💅

🎀 ARGUMENTS 🎀

  • ptr — the list head to take the element from. like, the starting point, the main character of this whole operation 👑
  • type — the type of the struct this is embedded in. yes it's embedded, she's not a standalone queen, she lives inside a bigger struct 💜
  • member — the name of the list_head within the struct. so we know exactly which little field we're vibing with 🎯

🌈 DESCRIPTION 🌈

okay here's the tea, and it's important: note that if the list is empty, it returns NULL. ✨ no element, no problem, you just get NULL and you better check for it, bestie 🙈

and now the iconic part — this primitive may safely run concurrently with the _rcu list-mutation primitives such as list_add_rcu, as long as it's guarded by rcu_read_lock. 🔥 that rcu_read_lock guard is not optional, it's the whole vibe check. skip it and you're in undefined-behaviour territory, fr fr 😭

⚠️ no cap: concurrent safety here is conditional. rcu_read_lock is the condition. don't fumble that.

👑 SEE ALSO 👑

bestie the cross-reference list is long and i'm obsessed, every single one made it in 👇

Kernel file ./include/linux/rculist.h:

like, she's connected to everyone. networking icon behavior 💀💖

okay that's the whole page bestie, go forth and read your RCU lists safely ✨

sign-off time 🎀 — this one lives in the kernel file ./include/linux, and the page itself is dated October 2026, so yeah, she's fresh. mwah 💋 🦋🌸💜

📦 where this page comes from