atomic64_fetch_add_acquire(9)

📦 version 7.3.1, in nixpkgs unstable

💖 atomic64_fetch_add_acquire — Kernel API Manual ✨

Bestie, welcome to the Kernel API Manual entry for atomic64_fetch_add_acquire(9). Yes, the manual name is literally in the title, we're keeping it, it's part of the vibe now. 💅 This one is a single function from ./include/linux/atomic and honestly? She's an icon. Let's get into it.

🌸 NAME 🌸

atomic64_fetch_add_acquire — atomic add with acquire ordering. That's it, that's the whole name, and it ate. 🔥

🦋 SYNOPSIS 🦋

s64 atomic64_fetch_add_acquire (s64 i , atomic64_t *v );

Look at her. Two arguments, one s64 return. Clean. Minimalist. Main character energy. 👑

🎀 ARGUMENTS 🎀

  • i — an s64 value, aka the number you're adding in. This is the "how much" of the whole situation. 🍓
  • v — a pointer to an atomic64_t. This is the thing getting updated, bestie. Point her at it and she goes. ✨

💜 DESCRIPTION 💜

Okay so here's the tea: this function atomically updates v to (v + i) with acquire ordering. Atomic means nobody can catch her mid-update — no half-done state, no messy in-between, no cap. 🫶 And the acquire ordering is part of the whole package, lowkey doing memory-ordering work for you while she's at it.

⚠️ Heads up, bestie: this is unsafe to use in noinstr code. If you're in noinstr, use raw_atomic64_fetch_add_acquire there instead. Not me warning you and then you doing it anyway — don't do it anyway. 😭 Use the raw one. Periodt.

🌈 RETURN 🌈

She returns the original value of v — like, the value before the add happened. So you get the before-pic while she posts the after-pic. Iconic behavior, honestly. 📸💖

⭐ SEE ALSO ⭐

Kernel file: ./include/linux/atomic/atomic-instrumented.h

Bestie, buckle up, because this list is long and every single one of these is invited to the party. 🎉 They're grouped here so your eyes don't melt, but not one of them got left off the guest list.

The atomic_ girlies (plain, non-64):

The atomic64_ section (our girl's home turf 💅):

The atomic_long_ crew (the long game 🧚):

Anyway, that's the whole page, bestie — no sections skipped, no flags dropped, we ate and left no crumbs. 🍓✨

Sign-off time: this lil beauty lives in the source/version ./include/linux/atomic and the date on the tin is October 2026, so if you're reading this from the future, hiii, hope the kernel is treating you well. 🦋💖 Bye bestie, go do some atomic adds. 💅

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