raw_atomic_cmpxchg(9)

💖 raw_atomic_cmpxchg — Kernel API Manual 💖

okay bestie, welcome to the Kernel API Manual entry for raw_atomic_cmpxchg — the compare-and-swap girlie with full-ordering energy. Let's get into it 💅

✨ NAME ✨

raw_atomic_cmpxchg — atomic compare and exchange with full ordering

🌸 SYNOPSIS 🌸

int raw_atomic_cmpxchg (atomic_t *v , int old , int new );

🎀 ARGUMENTS 🎀

• v — pointer to atomic_t
• old — int value to compare with
• new — int value to assign

💅 DESCRIPTION 💅

If (v == old), this atomically updates v to new with full ordering. Otherwise, v is not modified and relaxed ordering is provided.

Safe to use in noinstr code; prefer atomic_cmpxchg elsewhere.

no cap: that noinstr safety is the special sauce, and the man page still says prefer atomic_cmpxchg when you're not in noinstr 🫶

🫶 RETURN 🫶

The original value of v. That's it, that's the tea 💅

🦋 SEE ALSO 🦋

Kernel file: ./include/linux/atomic/atomic-arch-fallback.h

the cross-ref list is huge and I am not skipping a single one:

raw_atomic_read(9), raw_atomic_read_acquire(9), raw_atomic_set(9),
raw_atomic_set_release(9), raw_atomic_add(9), raw_atomic_add_return(9),
raw_atomic_add_return_acquire(9), raw_atomic_add_return_release(9),
raw_atomic_add_return_relaxed(9), raw_atomic_fetch_add(9),
raw_atomic_fetch_add_acquire(9), raw_atomic_fetch_add_release(9),
raw_atomic_fetch_add_relaxed(9), raw_atomic_sub(9),
raw_atomic_sub_return(9), raw_atomic_sub_return_acquire(9),
raw_atomic_sub_return_release(9), raw_atomic_sub_return_relaxed(9),
raw_atomic_fetch_sub(9), raw_atomic_fetch_sub_acquire(9),
raw_atomic_fetch_sub_release(9), raw_atomic_fetch_sub_relaxed(9),
raw_atomic_inc(9), raw_atomic_inc_return(9),
raw_atomic_inc_return_acquire(9), raw_atomic_inc_return_release(9),
raw_atomic_inc_return_relaxed(9), raw_atomic_fetch_inc(9),
raw_atomic_fetch_inc_acquire(9), raw_atomic_fetch_inc_release(9),
raw_atomic_fetch_inc_relaxed(9), raw_atomic_dec(9),
raw_atomic_dec_return(9), raw_atomic_dec_return_acquire(9),
raw_atomic_dec_return_release(9), raw_atomic_dec_return_relaxed(9),
raw_atomic_fetch_dec(9), raw_atomic_fetch_dec_acquire(9),
raw_atomic_fetch_dec_release(9), raw_atomic_fetch_dec_relaxed(9),
raw_atomic_and(9), raw_atomic_fetch_and(9),
raw_atomic_fetch_and_acquire(9), raw_atomic_fetch_and_release(9),
raw_atomic_fetch_and_relaxed(9), raw_atomic_andnot(9),
raw_atomic_fetch_andnot(9), raw_atomic_fetch_andnot_acquire(9),
raw_atomic_fetch_andnot_release(9), raw_atomic_fetch_andnot_relaxed(9),
raw_atomic_or(9), raw_atomic_fetch_or(9),
raw_atomic_fetch_or_acquire(9), raw_atomic_fetch_or_release(9),
raw_atomic_fetch_or_relaxed(9), raw_atomic_xor(9),
raw_atomic_fetch_xor(9), raw_atomic_fetch_xor_acquire(9),
raw_atomic_fetch_xor_release(9), raw_atomic_fetch_xor_relaxed(9),
raw_atomic_xchg(9), raw_atomic_xchg_acquire(9),
raw_atomic_xchg_release(9), raw_atomic_xchg_relaxed(9),
raw_atomic_cmpxchg_acquire(9), raw_atomic_cmpxchg_release(9),
raw_atomic_cmpxchg_relaxed(9), raw_atomic_try_cmpxchg(9),
raw_atomic_try_cmpxchg_acquire(9), raw_atomic_try_cmpxchg_release(9),
raw_atomic_try_cmpxchg_relaxed(9), raw_atomic_sub_and_test(9),
raw_atomic_dec_and_test(9), raw_atomic_inc_and_test(9),
raw_atomic_add_negative(9), raw_atomic_add_negative_acquire(9),
raw_atomic_add_negative_release(9), raw_atomic_add_negative_relaxed(9),
raw_atomic_fetch_add_unless(9), raw_atomic_add_unless(9),
raw_atomic_inc_not_zero(9), raw_atomic_inc_unless_negative(9),
raw_atomic_dec_unless_positive(9), raw_atomic_dec_if_positive(9),
raw_atomic64_read(9), raw_atomic64_read_acquire(9), raw_atomic64_set(9),
raw_atomic64_set_release(9), raw_atomic64_add(9),
raw_atomic64_add_return(9), raw_atomic64_add_return_acquire(9),
raw_atomic64_add_return_release(9), raw_atomic64_add_return_relaxed(9),
raw_atomic64_fetch_add(9), raw_atomic64_fetch_add_acquire(9),
raw_atomic64_fetch_add_release(9), raw_atomic64_fetch_add_relaxed(9),
raw_atomic64_sub(9), raw_atomic64_sub_return(9),
raw_atomic64_sub_return_acquire(9), raw_atomic64_sub_return_release(9),
raw_atomic64_sub_return_relaxed(9), raw_atomic64_fetch_sub(9),
raw_atomic64_fetch_sub_acquire(9), raw_atomic64_fetch_sub_release(9),
raw_atomic64_fetch_sub_relaxed(9), raw_atomic64_inc(9),
raw_atomic64_inc_return(9), raw_atomic64_inc_return_acquire(9),
raw_atomic64_inc_return_release(9), raw_atomic64_inc_return_relaxed(9),
raw_atomic64_fetch_inc(9), raw_atomic64_fetch_inc_acquire(9),
raw_atomic64_fetch_inc_release(9), raw_atomic64_fetch_inc_relaxed(9),
raw_atomic64_dec(9), raw_atomic64_dec_return(9),
raw_atomic64_dec_return_acquire(9), raw_atomic64_dec_return_release(9),
raw_atomic64_dec_return_relaxed(9), raw_atomic64_fetch_dec(9),
raw_atomic64_fetch_dec_acquire(9), raw_atomic64_fetch_dec_release(9),
raw_atomic64_fetch_dec_relaxed(9), raw_atomic64_and(9),
raw_atomic64_fetch_and(9), raw_atomic64_fetch_and_acquire(9),
raw_atomic64_fetch_and_release(9), raw_atomic64_fetch_and_relaxed(9),
raw_atomic64_andnot(9), raw_atomic64_fetch_andnot(9),
raw_atomic64_fetch_andnot_acquire(9),
raw_atomic64_fetch_andnot_release(9),
raw_atomic64_fetch_andnot_relaxed(9), raw_atomic64_or(9),
raw_atomic64_fetch_or(9), raw_atomic64_fetch_or_acquire(9),
raw_atomic64_fetch_or_release(9), raw_atomic64_fetch_or_relaxed(9),
raw_atomic64_xor(9), raw_atomic64_fetch_xor(9),
raw_atomic64_fetch_xor_acquire(9), raw_atomic64_fetch_xor_release(9),
raw_atomic64_fetch_xor_relaxed(9), raw_atomic64_xchg(9),
raw_atomic64_xchg_acquire(9), raw_atomic64_xchg_release(9),
raw_atomic64_xchg_relaxed(9), raw_atomic64_cmpxchg(9),
raw_atomic64_cmpxchg_acquire(9), raw_atomic64_cmpxchg_release(9),
raw_atomic64_cmpxchg_relaxed(9), raw_atomic64_try_cmpxchg(9),
raw_atomic64_try_cmpxchg_acquire(9),
raw_atomic64_try_cmpxchg_release(9),
raw_atomic64_try_cmpxchg_relaxed(9), raw_atomic64_sub_and_test(9),
raw_atomic64_dec_and_test(9), raw_atomic64_inc_and_test(9),
raw_atomic64_add_negative(9), raw_atomic64_add_negative_acquire(9),
raw_atomic64_add_negative_release(9),
raw_atomic64_add_negative_relaxed(9), raw_atomic64_fetch_add_unless(9),
raw_atomic64_add_unless(9), raw_atomic64_inc_not_zero(9),
raw_atomic64_inc_unless_negative(9),
raw_atomic64_dec_unless_positive(9), raw_atomic64_dec_if_positive(9)

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and that's the page, babe — source path ./include/linux/atomic, date October 2026, cute as ever 🌈💖