atomic_long...xchg_acquire(9)

💅 `atomic_long_try_cmpxchg_acquire(9)` — Kernel API Manual, bestie edition

okay so we're in the Kernel API Manual today, and the star of the show is atomic_long_try_cmpxchg_acquire (the header line calls it atomic_long...xchg_acquire(9) because apparently even kernel docs get tired and abbreviate 💀). Buckle up, this one's short but she is mighty.

✨ NAME ✨

atomic_long_try_cmpxchg_acquire — atomic compare and exchange with acquire ordering

Like, she compares, she exchanges, she gives you acquire ordering. Triple threat. Periodt. 👑

🌸 SYNOPSIS 🌸

bool atomic_long_try_cmpxchg_acquire (atomic_long_t *v , long *old ,
long new );

Three args, one bool back. That's the whole vibe check. 🦋

🎀 ARGUMENTS 🎀

v — pointer to atomic_long_t 💖 this is the thing getting compared-and-maybe-swapped, main character energy
old — pointer to long value to compare with 🔍 you bring the value you think is in there
new — long value to assign 🌟 the value that gets to move in if old was right

🫶 DESCRIPTION 🫶

okay so picture this: (v == old)? Then she atomically updates v to new with acquire ordering. Slay, done, iconic. ✨

But if that comparison does not match? Then v is not modified 🚫, old gets updated to the current value of v (so you can see what was actually there, very helpful of her 🥰), and relaxed ordering is provided.

⚠️ ngl there's a catch: this is unsafe to use in noinstr code. Use raw_atomic_long_try_cmpxchg_acquire there instead. fr fr, don't skip that part 😭

🌈 RETURN 🌈

true — the exchange occurred 🎉 (your old was correct, the swap went through)
false — otherwise 💀 (no swap, but old got the real current value so you can try again)

🔥 SEE ALSO 🔥

Everything below lives in the kernel file ./include/linux/atomic/atomic-instrumented.h, and bestie, this family tree is huge — it's giving royal dynasty. Here's literally every single one, in order, no skips: 💅

atomic gang, part 1 — reading, setting and adding:

atomic_read(9), atomic_read_acquire(9), atomic_set(9), atomic_set_release(9), atomic_add(9), atomic_add_return(9), atomic_add_return_acquire(9), atomic_add_return_release(9), atomic_add_return_relaxed(9), atomic_fetch_add(9), atomic_fetch_add_acquire(9), atomic_fetch_add_release(9), atomic_fetch_add_relaxed(9)

atomic gang, part 2 — subtracting:

atomic_sub(9), atomic_sub_return(9), atomic_sub_return_acquire(9), atomic_sub_return_release(9), atomic_sub_return_relaxed(9), atomic_fetch_sub(9), atomic_fetch_sub_acquire(9), atomic_fetch_sub_release(9), atomic_fetch_sub_relaxed(9)

atomic gang, part 3 — inc and dec, the whole clique:

atomic_inc(9), atomic_inc_return(9), atomic_inc_return_acquire(9), atomic_inc_return_release(9), atomic_inc_return_relaxed(9), atomic_fetch_inc(9), atomic_fetch_inc_acquire(9), atomic_fetch_inc_release(9), atomic_fetch_inc_relaxed(9), atomic_dec(9), atomic_dec_return(9), atomic_dec_return_acquire(9), atomic_dec_return_release(9), atomic_dec_return_relaxed(9), atomic_fetch_dec(9), atomic_fetch_dec_acquire(9), atomic_fetch_dec_release(9), atomic_fetch_dec_relaxed(9)

atomic gang, part 4 — bitwise and / andnot:

atomic_and(9), atomic_fetch_and(9), atomic_fetch_and_acquire(9), atomic_fetch_and_release(9), atomic_fetch_and_relaxed(9), atomic_andnot(9), atomic_fetch_andnot(9), atomic_fetch_andnot_acquire(9), atomic_fetch_andnot_release(9), atomic_fetch_andnot_relaxed(9)

atomic gang, part 5 — or / xor:

atomic_or(9), atomic_fetch_or(9), atomic_fetch_or_acquire(9), atomic_fetch_or_release(9), atomic_fetch_or_relaxed(9), atomic_xor(9), atomic_fetch_xor(9), atomic_fetch_xor_acquire(9), atomic_fetch_xor_release(9), atomic_fetch_xor_relaxed(9)

atomic gang, part 6 — xchg and cmpxchg (our girl's cousins):

atomic_xchg(9), atomic_xchg_acquire(9), atomic_xchg_release(9), atomic_xchg_relaxed(9), atomic_cmpxchg(9), atomic_cmpxchg_acquire(9), atomic_cmpxchg_release(9), atomic_cmpxchg_relaxed(9), atomic_try_cmpxchg(9), atomic_try_cmpxchg_acquire(9), atomic_try_cmpxchg_release(9), atomic_try_cmpxchg_relaxed(9)

atomic gang, part 7 — tests and "unless" girlies:

atomic_sub_and_test(9), atomic_dec_and_test(9), atomic_inc_and_test(9), atomic_add_negative(9), atomic_add_negative_acquire(9), atomic_add_negative_release(9), atomic_add_negative_relaxed(9), atomic_fetch_add_unless(9), atomic_add_unless(9), atomic_inc_not_zero(9), atomic_inc_unless_negative(9), atomic_dec_unless_positive(9), atomic_dec_if_positive(9)

the atomic64 era, part 1 — read / set / add:

atomic64_read(9), atomic64_read_acquire(9), atomic64_set(9), atomic64_set_release(9), atomic64_add(9), atomic64_add_return(9), atomic64_add_return_acquire(9), atomic64_add_return_release(9), atomic64_add_return_relaxed(9), atomic64_fetch_add(9), atomic64_fetch_add_acquire(9), atomic64_fetch_add_release(9), atomic64_fetch_add_relaxed(9)

the atomic64 era, part 2 — sub:

atomic64_sub(9), atomic64_sub_return(9), atomic64_sub_return_acquire(9), atomic64_sub_return_release(9), atomic64_sub_return_relaxed(9), atomic64_fetch_sub(9), atomic64_fetch_sub_acquire(9), atomic64_fetch_sub_release(9), atomic64_fetch_sub_relaxed(9)

the atomic64 era, part 3 — inc / dec:

atomic64_inc(9), atomic64_inc_return(9), atomic64_inc_return_acquire(9), atomic64_inc_return_release(9), atomic64_inc_return_relaxed(9), atomic64_fetch_inc(9), atomic64_fetch_inc_acquire(9), atomic64_fetch_inc_release(9), atomic64_fetch_inc_relaxed(9), atomic64_dec(9), atomic64_dec_return(9), atomic64_dec_return_acquire(9), atomic64_dec_return_release(9), atomic64_dec_return_relaxed(9), atomic64_fetch_dec(9), atomic64_fetch_dec_acquire(9), atomic64_fetch_dec_release(9), atomic64_fetch_dec_relaxed(9)

the atomic64 era, part 4 — and / andnot:

atomic64_and(9), atomic64_fetch_and(9), atomic64_fetch_and_acquire(9), atomic64_fetch_and_release(9), atomic64_fetch_and_relaxed(9), atomic64_andnot(9), atomic64_fetch_andnot(9), atomic64_fetch_andnot_acquire(9), atomic64_fetch_andnot_release(9), atomic64_fetch_andnot_relaxed(9)

the atomic64 era, part 5 — or / xor:

atomic64_or(9), atomic64_fetch_or(9), atomic64_fetch_or_acquire(9), atomic64_fetch_or_release(9), atomic64_fetch_or_relaxed(9), atomic64_xor(9), atomic64_fetch_xor(9), atomic64_fetch_xor_acquire(9), atomic64_fetch_xor_release(9), atomic64_fetch_xor_relaxed(9)

the atomic64 era, part 6 — xchg / cmpxchg / try_cmpxchg:

atomic64_xchg(9), atomic64_xchg_acquire(9), atomic64_xchg_release(9), atomic64_xchg_relaxed(9), atomic64_cmpxchg(9), atomic64_cmpxchg_acquire(9), atomic64_cmpxchg_release(9), atomic64_cmpxchg_relaxed(9), atomic64_try_cmpxchg(9), atomic64_try_cmpxchg_acquire(9), atomic64_try_cmpxchg_release(9), atomic64_try_cmpxchg_relaxed(9)

the atomic64 era, part 7 — tests and unless:

atomic64_sub_and_test(9), atomic64_dec_and_test(9), atomic64_inc_and_test(9), atomic64_add_negative(9), atomic64_add_negative_acquire(9), atomic64_add_negative_release(9), atomic64_add_negative_relaxed(9), atomic64_fetch_add_unless(9), atomic64_add_unless(9), atomic64_inc_not_zero(9), atomic64_inc_unless_negative(9), atomic64_dec_unless_positive(9), atomic64_dec_if_positive(9)

the atomic_long era, part 1 — read / set / add:

atomic_long_read(9), atomic_long_read_acquire(9), atomic_long_set(9), atomic_long_set_release(9), atomic_long_add(9), atomic_long_add_return(9), atomic_long_add_return_acquire(9), atomic_long_add_return_release(9), atomic_long_add_return_relaxed(9), atomic_long_fetch_add(9), atomic_long_fetch_add_acquire(9), atomic_long_fetch_add_release(9), atomic_long_fetch_add_relaxed(9)

the atomic_long era, part 2 — sub:

atomic_long_sub(9), atomic_long_sub_return(9), atomic_long_sub_return_acquire(9), atomic_long_sub_return_release(9), atomic_long_sub_return_relaxed(9), atomic_long_fetch_sub(9), atomic_long_fetch_sub_acquire(9), atomic_long_fetch_sub_release(9), atomic_long_fetch_sub_relaxed(9)

the atomic_long era, part 3 — inc / dec:

the atomic_long era, part 4 — and / andnot:

atomic_long_and(9), atomic_long_fetch_and(9), atomic_long_fetch_and_acquire(9), atomic_long_fetch_and_release(9), atomic_long_fetch_and_relaxed(9), atomic_long_andnot(9), atomic_long_fetch_andnot(9), atomic_long_fetch_andnot_acquire(9), atomic_long_fetch_andnot_release(9), atomic_long_fetch_andnot_relaxed(9)

the atomic_long era, part 5 — or / xor:

atomic_long_or(9), atomic_long_fetch_or(9), atomic_long_fetch_or_acquire(9), atomic_long_fetch_or_release(9), atomic_long_fetch_or_relaxed(9), atomic_long_xor(9), atomic_long_fetch_xor(9), atomic_long_fetch_xor_acquire(9), atomic_long_fetch_xor_release(9), atomic_long_fetch_xor_relaxed(9)

the atomic_long era, part 6 — xchg / cmpxchg / try_cmpxchg (our girl's actual siblings, notice she's not listed in her own SEE ALSO, she's too busy being the page 💅):

atomic_long_xchg(9), atomic_long_xchg_acquire(9), atomic_long_xchg_release(9), atomic_long_xchg_relaxed(9), atomic_long_cmpxchg(9), atomic_long_cmpxchg_acquire(9), atomic_long_cmpxchg_release(9), atomic_long_cmpxchg_relaxed(9), atomic_long_try_cmpxchg(9), atomic_long_try_cmpxchg_release(9), atomic_long_try_cmpxchg_relaxed(9)

the atomic_long era, part 7 — tests and unless:

atomic_long_sub_and_test(9), atomic_long_dec_and_test(9), atomic_long_inc_and_test(9), atomic_long_add_negative(9), atomic_long_add_negative_acquire(9), atomic_long_add_negative_release(9), atomic_long_add_negative_relaxed(9), atomic_long_fetch_add_unless(9), atomic_long_add_unless(9), atomic_long_inc_not_zero(9), atomic_long_inc_unless_negative(9), atomic_long_dec_unless_positive(9), atomic_long_dec_if_positive(9)

and that's the whole fam, no cap 🧚💜

okay bye bestie, this page came from the source/version ./include/linux/atomic and it's dated October 2026 — go forth and compare-and-exchange responsibly, mwah 💖🎀🦋

📦 where this page comes from

nixpkgs unstable: linux-manual 7.3.1
💖 girlified by deepseek-ai/DeepSeek-V4.1-Flash-1017 on 2026-11-04: a language model's rewrite of the original, under its terms