atomic64_cmpxchg_release(9)

📦 version 7.3.1, in nixpkgs unstable

💅 atomic64_cmpxchg_release — straight from the Kernel API Manual, section 9 ✨

okay so bestie, welcome to the glow-up corner of the kernel docs where we talk about everyone's favorite "did it actually match tho" atomic operation 🎀 this one's called atomic64_cmpxchg_release and it's giving main character energy in the 64-bit compare-and-swap cinematic universe 💖

🌸 NAME 🌸

atomic64_cmpxchg_release — atomic compare and exchange with release ordering 🔥

✨ SYNOPSIS ✨

s64 atomic64_cmpxchg_release (atomic64_t *v , s64 old , s64 new );

🫶 ARGUMENTS 🫶

  • v — pointer to atomic64_t 💫 (this is the thing we're side-eyeing)
  • old — s64 value to compare with 👀 (the vibe check target)
  • new — s64 value to assign 🎁 (the glow-up replacement)

💀 DESCRIPTION 💀

so here's the tea: if (v == old), it atomically updates v to new with release ordering 🦋. love that for us.

Otherwise, v is not modified and relaxed ordering is provided 🙈 — like, no changes, we just move on, no cap.

⚠️ Unsafe to use in noinstr code; use raw_atomic64_cmpxchg_release there. fr fr, don't do it in noinstr code, she said what she said 💅

👑 RETURN 👑

The original value of v 🌈 — yes, the original, like a before pic 📸

🧚 SEE ALSO 🧚

literally the whole extended friend group, all from the kernel file ./include/linux/atomic/atomic-instrumented.h 💜

🍓 the atomic_* girlies

🦋 the atomic64_* icons (our girl's home turf)

🌈 the atomic_long_* cousins

okay that's the whole page bestie, go be atomic out there 🔥🫶

source: ./include/linux/atomic · date: October 2026 · mwah, that's the sign-off, ty for coming to my ted talk 💜✨🎀

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