atomic_long..._sub_acquire(9)

📦 version 7.3.1, in nixpkgs unstable

💅 atomic_long_fetch_sub_acquire — from the Kernel API Manual, section 9, bestie 🎀

okay so you opened the Kernel API Manual and landed on atomic_long_fetch_sub_acquire, and honestly? iconic choice. this is the atomic subtract situation, acquire-flavoured, and i'm gonna walk you through it like we're texting at 2am. 🦋

✨ NAME ✨

atomic_long_fetch_sub_acquire — atomic subtract with acquire ordering. that's it, that's the whole vibe. 💖

🌸 SYNOPSIS 🌸

long atomic_long_fetch_sub_acquire (long i , atomic_long_t *v );

look at her. two args, returns a long, does exactly one thing. main character energy. 👑

🎀 ARGUMENTS 🎀

  • i — a long value, and it's the amount you're subtracting. like, the thing getting taken away. 🍓
  • v — pointer to your atomic_long_t. this is the one being updated, so be nice to her.

💅 DESCRIPTION 💅

okay so the whole bit: it atomically updates v to (v - i) with acquire ordering. atomically means nobody can sneak a peek at a half-done state, and acquire ordering is the memory-ordering flavour you're getting. no cap. ⭐

⚠️ real talk though — unsafe to use in noinstr code. if you're in noinstr, use raw_atomic_long_fetch_sub_acquire there instead. do not ignore this, i'm literally begging. 😭

🔥 RETURN 🔥

the original value of v. so like, the value from before the subtract happened. she remembers what she was. 🙈

🌈 SEE ALSO 🌈

these are all chillin' in the kernel file ./include/linux/atomic/atomic-instrumented.h, and yes there are a LOT of them, buckle up bestie 💀

and now the 64-bit girlies 🧚

aaaand the long crew, aka our own family 🫶

and that's the whole page, bestie, you ate it 💜 this cutie came out of ./include/linux/atomic, dated October 2026, and she's filed as atomic_long..._sub_acquire(9) — go forth and subtract atomically, mwah 🧚✨🌸

📦 where this page comes from