atomic64_cmpxchg_acquire(9)

📦 version 7.3.1, in nixpkgs unstable

💅 atomic64_cmpxchg_acquire — from the Kernel API Manual, section 9

okay so bestie, welcome to atomic64_cmpxchg_acquire(9) — yes that's the whole title, yes it's a mouthful, and yes it's from the Kernel API Manual. section 9. iconic behavior. let's get into it 🫶

✨ NAME ✨

atomic64_cmpxchg_acquire — it's an atomic compare and exchange, but make it acquire ordering. like, the vibes are ordered. memory-ordering ordered, specifically 🌸

🎀 SYNOPSIS 🎀

s64 atomic64_cmpxchg_acquire (atomic64_t *v , s64 old , s64 new );

that's the whole signature. three args, one s64 coming back at you. slay.

🌈 ARGUMENTS 🌈

  • v — pointer to atomic64_t. it's giving "here's the thing we're about to mess with" energy 👑
  • old — the s64 value to compare with. the vibe check value, if you will 💅
  • new — the s64 value to assign. what v becomes if it passes the vibe check ✨

🦋 DESCRIPTION 🦋

so here's the tea, bestie: if (v == old), it atomically updates v to new with acquire ordering. otherwise, v is not modified and relaxed ordering is provided. no cap, that's the whole deal — the ordering you get depends on whether the swap actually happened. the way that's lowkey elegant 😭

⚠️ unsafe to use in noinstr code — use raw_atomic64_cmpxchg_acquire there instead. fr fr, do not skip this one, it's a real warning, not a vibe 💀

🔥 RETURN 🔥

the original value of v. that's it. that's the return. you always find out what was there before 🍓

👑 SEE ALSO 👑

okay so this is the part where I tell you there are a lot of friends. like, an unreasonable number of friends. all of these live in the kernel file ./include/linux/atomic/atomic-instrumented.h 🧚 and every single one of them is a real page, so:

that's all of them. I counted. twice. go read some, iykyk 💜

<div align="center">🌸 🌸 🌸</div>

and that's the page, bestie!! this little beauty ships from ./include/linux/atomic, dated October 2026 — so yeah, mark your calendar, it's giving futuristic. mwah, go forth and compare-and-exchange responsibly 💖✨🎀

📦 where this page comes from