wait_on_bit_lock(9)

📦 version 7.3.1, in nixpkgs unstable

💅 wait_on_bit_lock(9) — like, the kernel API manual, bestie ✨

okay so welcome to the glow-up of wait_on_bit_lock, a kernel API manual page, and honestly? she's iconic. buckle up 🎀

🌸 NAME 🌸

wait_on_bit_lock — wait for a bit to be cleared, then set it. that's the whole vibe. wait, then snatch. 💅

✨ SYNOPSIS ✨

int wait_on_bit_lock (unsigned long *word , int bit , unsigned mode );

🫶 ARGUMENTS 🫶

  • word — the address containing the bit being waited on. it's giving "where the drama lives" 📍
  • bit — the bit of the word being waited on and set. yes, both. she's multitalented 💁‍♀️
  • mode — the task state to sleep in 😴 the actual napping configuration, no cap

🦋 DESCRIPTION 🦋

okay so picture this: you're waiting for the given bit in an unsigned long or a bitmap (see DECLARE_BITMAP) to be cleared. cleared. gone. bye. 👋

and like — important — the clearing of the bit must be signalled with wake_up_bit, often as clear_and_wake_up_bit. that's the bat signal, bestie. no signal, no party 🚨

as soon as it's clear, this function atomically sets it and returns. atomic. like she does it all in one breath, no gaps, no interleaving. main character energy 🔥

this is similar to wait_on_bit, but sets the bit before returning. so like, her cousin, but she does more 💅

the returned value will be zero if the bit was successfully set — and in that case the call has the same memory sequencing semantics as test_and_clear_bit — or it'll be -EINTR if the process received a signal and the mode permitted wake up on that signal 🙈

lowkey important: -EINTR means a signal barged in mid-nap. that's not a bug, that's the mode you asked for 💀

🧚 SEE ALSO 🧚

kernel file ./include/linux/wait_bit.h, plus the whole friend group, fr fr:

and that's the page, bestie 🍓 bye bestie, go set some bits 💜 — this one's from ./include/linux, dated October 2026, and it's wait_on_bit_lock(9) all the way down 🌈⭐👑

📦 where this page comes from