raw_atomic_f..._sub_acquire(9)

🦋 raw_atomic_f..._sub_acquire — the Kernel API Manual, bestie edition 🦋

okay so real talk, this one's from the Kernel API Manual and the name is lowkey a mouthful because the full thing is raw_atomic_fetch_sub_acquire, but the header abbreviates it and honestly? iconic of it. let's get into it 💅

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✨ NAME ✨

raw_atomic_fetch_sub_acquire — atomic subtract with acquire ordering. that's it, that's the whole vibe. subtract, but make it atomic, and with acquire ordering. periodt 🎀

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🌸 SYNOPSIS 🌸

int raw_atomic_fetch_sub_acquire (int i , atomic_t *v );

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💖 ARGUMENTS 💖

• i — an int, and it's the value you're subtracting. like, the amount coming off. no cap.
• v — a pointer to atomic_t. this is the thing getting updated, bestie. handle with care 🫶

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🔥 DESCRIPTION 🔥

So what it does: it atomically updates v to (v - i), and it does it with acquire ordering. atomically means nobody can catch it mid-subtract, and acquire ordering means the memory rules are doing their little synchronization dance. slay. ✨

It's safe to use in noinstr code — which is a whole special club, iykyk. but everywhere else? prefer atomic_fetch_sub_acquire instead. the raw_ version is the one you reach for when you literally can't use the normal one. ngl, respect the hustle.

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👑 RETURN 👑

The original value of v — like, what it was before the subtract happened. so you get the receipt, not the new total. 💖

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🌈 SEE ALSO 🌈

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

and now, the guest list. it's long. it's giving family reunion. every single one of these showed up:

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_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_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 whole page, bestie!! 💜 source path is ./include/linux/atomic and it's dated October 2026 — so yeah, bookmark it, screenshot it, put it on your fridge. mwah 🫶✨