hlist_nulls_...ace_init_rcu(9)

📦 version 7.3.1, in nixpkgs unstable

💅 NAME 💅

ok so bestie, this one is hlist_nulls_replace_init_rcu — it replaces an old entry with a new one and initializes the old one, all in one lil move ✨ (this is from the Kernel API Manual, in case the vibe check was unclear 🫶)

🦋 SYNOPSIS 🦋

void hlist_nulls_replace_init_rcu (struct hlist_nulls_node *old , struct hlist_nulls_node *new );

like literally that's it, void in, no return value out, no drama 💅

🎀 ARGUMENTS 🎀

  • old — the element that's getting replaced 👋 she's being swapped out, and she's also getting initialized by the end of this, so don't be shocked
  • new — the shiny new element to insert in her place 👑 main character energy fr fr

🌸 DESCRIPTION 🌸

So here's the tea, bestie ☕ — this function replaces the old entry with the new one inside a RCU-protected hlist_nulls, and it does it while allowing racing traversals to keep happening 😭 like nobody has to stop walking the list, it's giving "smooth operator", it's giving "no locks dropped", periodt.

And then — because it's not done slaying — it reinitializes the old entry too. Two jobs, one function, iconic behavior ngl 💅✨

⚠️ NOTE ⚠️

old must be hashed. like for real, no cap, that's not optional 🙈

The caller has to take whatever precautions are necessary (such as holding appropriate locks) to avoid racing with another list-mutation primitive running on this same list — think stuff like hlist_nulls_add_head_rcu or hlist_nulls_del_rcu 💀 do NOT let two mutators scrap over the same list, that's not the vibe.

BUT — and this is the fun part 🎉 — it is perfectly legal to run concurrently with the _rcu list-traversal primitives, such as hlist_nulls_for_each_entry_rcu. Traversals? oh they can vibe alongside you all day, that's literally the whole point 🧚💜

🔥 SEE ALSO 🔥

Kernel file ./include/linux/rculist_nulls.h 📁 and all her friends:

go read them, they're all icons, iykyk ⭐

okok that's the whole thing bestie, mwah 💖 this lil gem lives over in ./include/linux 📂, dated October 2026, and it's filed under hlist_nulls_...ace_init_rcu(9) — go forth and replace responsibly, and remember: lock it before you rock it 🎀💜🫶

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