atomic64_try...xchg_acquire(9)

📦 version 7.3.1, in nixpkgs unstable

💅 atomic64_try_cmpxchg_acquire(9) — Kernel API Manual ✨

okay bestie, welcome to section 9 of the Kernel API Manual, where we stan one (1) very specific atomic compare-and-swap and honestly? she eats. 🍓

🌸 NAME 🌸

atomic64_try_cmpxchg_acquire — atomic compare and exchange with acquire ordering 🎀

✨ SYNOPSIS ✨

bool atomic64_try_cmpxchg_acquire (atomic64_t *v , s64 *old , s64 new );

🦋 ARGUMENTS 🦋

  • v — pointer to atomic64_t. this is the main character, the thing we're trying to swap out 👑
  • old — pointer to the s64 value to compare with. literally the "are you the one?" checkpoint 💅
  • new — the s64 value to assign. the glow-up we're swapping in 🌈

💖 DESCRIPTION 💖

so here's the vibe: if (v == old), the kernel atomically updates v to new with acquire ordering. slay. ✨

otherwise (and this is the important part, don't skip it) v is not modified, old gets updated to the current value of v, and relaxed ordering is provided. no cap, that's the whole deal. 🫶

⚠️ okay so this one is unsafe to use in noinstr code — use raw_atomic64_try_cmpxchg_acquire there instead. iykyk, please don't come for me if you ignore this 🙈

💀 RETURN 💀

true if the exchange occurred, false otherwise. that's it, that's the return. simple queen behaviour 💅

👑 SEE ALSO 👑

first up, the source file so you can go read the real thing:

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

and now the extended family — every single one of these (9) pages, no skips, no cuts, we're doing the whole group chat 🧚

🩷 the atomic_* girlies

🎀 the atomic64_* besties (our girl's home turf)

🦋 the atomic_long_* cousins

and that's the whole page, bestie 🫶 this one came from ./include/linux/atomic, dated October 2026, and it's filed under atomic64_try...xchg_acquire(9) — mwah, go atomically exchange something responsibly 💜⭐

📦 where this page comes from