unlink_binfmt_handler(9)

📦 version 7.3.1, in nixpkgs unstable

okay so bestie, welcome to the glow-up of unlink_binfmt_handler(9) ✨ this is a kernel API manual page and honestly? it's giving "short but does the most" 🎀

🌸 NAME 🌸

unlink_binfmt_handler — unhash a binary type handler, that's literally it, that's the whole job 💅

✨ SYNOPSIS ✨

void unlink_binfmt_handler (struct binfmt_misc *misc , struct
binfmt_misc_entry *e );

no cap, that's the exact signature, copied character for character because we do not play with kernel prototypes 🙈

🫶 ARGUMENTS 🫶

  • misc — the handle to your binfmt_misc instance. like, which one. there are several. it needs to know 🌈
  • e — the binary type handler you're un-hashing. yes, this one. bye bestie 👋

💖 DESCRIPTION 💖

so here's the tea, and it's actually kind of iconic 🍓

Adding and removing entries via bm_{entry,register,status}_write and unlink(2) all happens under the exclusively held inode lock of the root dentry — which is what keeps the list stable for the writers. main character lock energy, honestly 👑

Meanwhile load_misc_binary walks that list concurrently under SRCU. so the lock isn't holding everybody hostage, it's just doing its little job 🦋

And entries_lock? it's only held around the actual unlink, purely to serialize against bm_evict_inode, which unlinks entries during umount without holding the root inode lock. so entries_lock is the tiny bouncer at the door for exactly that one situation 💀

fr fr, if you're touching this, respect the lock discipline — the description is very specific about which lock is held where and why, and that's not decorative ✨

🧚 SEE ALSO 🧚

Kernel file ./fs/binfmt_misc.c, plus the whole friend group:

iykyk 🔥

aaaand that's the page!! 🎀 this masterpiece lives in ./fs and it's dated October 2026 — mwah, slay, periodt 💜

📦 where this page comes from