atomic_fetch_sub_relaxed(9)

📦 version 7.3.1, in nixpkgs unstable

💖 NAME 💖

okay so welcome to the Kernel API Manual, bestie — today’s main character is atomic_fetch_sub_relaxed, and she’s literally an atomic subtract with relaxed ordering. no cap. 🫶

✨ SYNOPSIS ✨

int atomic_fetch_sub_relaxed (int i , atomic_t *v );

🎀 ARGUMENTS 🎀

  • i — the int value you’re subtracting. that’s the amount getting yeeted. 💅
  • v — pointer to an atomic_t. this is the lucky variable getting updated. 🎀

🦋 DESCRIPTION 🦋

so here’s the vibe: this function atomically updates v to (v - i) with relaxed ordering. like, it does the subtraction all at once, no messy in-between state, periodt. ✨

⚠️ but bestie, careful — it’s unsafe to use in noinstr code. use raw_atomic_fetch_sub_relaxed there instead. no exceptions, fr fr. 💀

🌸 RETURN 🌸

it returns the original value of v — like, the value before the subtraction happened. it’s giving “receipts before the glow-up.” 💅🔥

💅 SEE ALSO 💅

kernel file: ./include/linux/atomic/atomic-instrumented.h, plus literally the whole atomic family (iykyk):

first up, the atomic_ crew:

then the atomic64_ girlies:

and finally the atomic_long_ squad:

source: ./include/linux/atomic · date: October 2026 · page: atomic_fetch_sub_relaxed(9) — mwah, slay, bye bestie 💋🌈

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