atomic_sub_return_relaxed(9)

📦 version 7.3.1, in nixpkgs unstable

💅 atomic_sub_return_relaxed 💅

okay so you're in the Kernel API Manual, bestie, and we're talking about one very specific little atomic function. buckle up 🎀

🌸 NAME 🌸

atomic_sub_return_relaxed — atomic subtract with relaxed ordering ✨

✨ SYNOPSIS ✨

int atomic_sub_return_relaxed (int i , atomic_t *v );

🫶 ARGUMENTS 🫶

  • i — an int, and it's the value you're subtracting. that's it, that's the number 💖
  • v — a pointer to an atomic_t. this is the thing getting updated, no cap 🦋

💖 DESCRIPTION 💖

So the whole vibe: this atomically updates v to (v - i) with relaxed ordering. atomic means nobody can catch it mid-subtract, it just happens, periodt 🔥

⚠️ Unsafe to use in noinstr code — like, genuinely do not. if you're in noinstr code, use raw_atomic_sub_return_relaxed there instead. this is a real caveat, not a drill, bestie 💀

🎀 RETURN 🎀

It gives you back the updated value of v — the value after the subtraction, not the old one. that's the whole point, iykyk 😌

🌈 SEE ALSO 🌈

Kernel file ./include/linux/atomic/atomic-instrumented.h — that's where the magic lives 🧚 and here's the whole extended friend group, literally everyone:

the atomic_ girlies — reads, sets, adds

the atomic_ sub crew

inc/dec energy

bitwise besties

swaps and compare-swaps

tests, negatives, and the "unless" squad

🌟 the 64-bit edition 🌟

🦋 the long edition 🦋

and that's the whole page, bestie 💜 go subtract something atomically and remember: relaxed ordering, not relaxed attitude about noinstr code 😤

source: ./include/linux/atomic — dated October 2026 🗓️ mwah 💋

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