raw_atomic_inc_and_test(9)

💅 raw_atomic_inc_and_test(9) — the Kernel API Manual, bestie edition ✨

okay so welcome to section 9 of the Kernel API Manual, where we talk about raw_atomic_inc_and_test — the little function that bumps a number up by one and then tells you if it landed on zero. it's giving "did we just close the last reference" energy and honestly? iconic.

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🌸 NAME 🌸

raw_atomic_inc_and_test — atomic increment and test if zero, with full ordering. like, all the ordering. no crumbs left for the compiler. 💅

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🎀 SYNOPSIS 🎀

bool raw_atomic_inc_and_test (atomic_t *v );

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🦋 ARGUMENTS 🦋

• v — pointer to atomic_t. that's it. that's the whole argument. she's lowkey low-maintenance. 🫶

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✨ DESCRIPTION ✨

so what she does: she atomically updates v to (v + 1) with full ordering. atomically means nobody can sneak in and peek at a half-finished value — it's all or nothing, no in-between era. 🔥

and the full ordering part means the memory barriers are doing their whole job, not a relaxed little half-effort. very main character. 👑

she's also safe to use in noinstr code — that's the special little corner of the kernel where instrumentation isn't allowed, and she's certified to be there. 🧚

ngl though, if you're not in noinstr code, prefer atomic_inc_and_test elsewhere. she said it herself, bestie. this raw_ version is the specialist. 💖

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💜 RETURN 💜

• true if the resulting value of v is zero 🎉
• false otherwise 🙈

that's the whole vibe check. inc, then test, then answer.

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🌈 SEE ALSO 🌈

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

and now, the friend group. literally the entire raw_atomic family reunion — every single one of them, in order, no cap:

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(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_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)

like I said. the whole group chat. 💀

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anyway that's the page 🥰 source is ./include/linux/atomic, dated October 2026 — so go forth, increment things atomically, and remember: full ordering or nothing, bestie. periodt. 💖✨🎀