atomic64_xchg(9)

📦 version 7.3.1, in nixpkgs unstable

💅 atomic64_xchg — Kernel API Manual 💅

okay so bestie, you're reading atomic64_xchg(9) from the Kernel API Manual, and honestly? She's a classic. Let's get into it 🫶

✨ NAME ✨

atomic64_xchg — atomic exchange with full ordering 🌈

🦋 SYNOPSIS 🦋

s64 atomic64_xchg (atomic64_t *v , s64 new );

🌸 ARGUMENTS 🌸

  • v — pointer to atomic64_t 💫 (this is the thing you're swapping into)
  • new — the s64 value to assign 🎀

💖 DESCRIPTION 💖

She atomically updates v to new, and does it with full ordering ✨. Like, the whole thing is one unit of swappy-swap, no cap. No half-states, no "oops I saw the middle", just boom — done 🧚

⚠️ okay so this is the important part: it's unsafe to use in noinstr code 💀. If you're in noinstr land, you use raw_atomic64_xchg there instead. That's the rule, fr fr.

🎀 RETURN 🎀

The original value of v — aka what was there before you came in and replaced it 👑

🌈 SEE ALSO 🌈

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

And now, the friend group 🫶 — the whole 32-bit atomic_* gang:

The 64-bit girlies (atomic64_* — this is our house 🏠, bestie):

And the atomic_long_* cousins slaying on the side 👑:

🌸 that's the whole page, bestie — go swap something atomically and stay ordered out there 💅✨

./include/linux/atomic — October 2026 🎀 that's where this queen lives and when she was last seen, mwah 💋

📦 where this page comes from