atomic_fetch_dec(9)

💅 atomic_fetch_dec — like, the manual (section 9, kernel API vibes) 🎀

okay bestie, so this is atomic_fetch_dec(9) from the kernel API manual, and lemme tell you, it's a tiny little function with main character energy ✨

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💖 NAME 💖

atomic_fetch_dec — atomic decrement with full ordering. that's it. that's the whole gig. ngl it's iconic in its simplicity 🦋

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✨ SYNOPSIS ✨

int atomic_fetch_dec (atomic_t *v );

one function, one pointer, zero drama. copy it exactly, bestie, don't get creative with the spacing 🙈

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🌸 ARGUMENTS 🌸

• v — pointer to atomic_t. that's your target, the thing you're about to knock down by one. handle her with care 💅

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🔥 DESCRIPTION 🔥

so here's the tea: this function atomically updates v to (v - 1) with full ordering. atomically means nobody can catch her mid-decrement — it's all one glorious operation, no peeking ✨ and full ordering means the memory barriers are doing their whole choreography so it all lands in the right order. periodt.

⚠️ lowkey important warning: atomic_fetch_dec is unsafe to use in noinstr code. if you're living in noinstr land, use raw_atomic_fetch_dec there instead. no cap, that's the rule 💀

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👑 RETURN 👑

it hands you back the original value of v — like, the value before she got decremented. so you get the before pic, not the after pic 📸 the way that's actually so useful for counters and refcounts, iykyk.

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🌈 SEE ALSO 🌈

the kernel file lives at ./include/linux/atomic/atomic-instrumented.h and honestly, this family is HUGE. grab a snack 🍓, here's literally everyone:

atomic_* girlies:

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_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_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_acquire(9),
atomic_fetch_dec_release(9), atomic_fetch_dec_relaxed(9), 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_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_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_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)

atomic64_* besties (the 64-bit girlies):

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), 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), 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), 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), 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), 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), 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)

atomic_long_* crew:

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), 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),
atomic_long_inc(9), atomic_long_inc_return(9), atomic_long_inc_return_acquire(9),
atomic_long_inc_return_release(9), atomic_long_inc_return_relaxed(9),
atomic_long_fetch_inc(9), atomic_long_fetch_inc_acquire(9),
atomic_long_fetch_inc_release(9), atomic_long_fetch_inc_relaxed(9),
atomic_long_dec(9), atomic_long_dec_return(9), atomic_long_dec_return_acquire(9),
atomic_long_dec_return_release(9), atomic_long_dec_return_relaxed(9),
atomic_long_fetch_dec(9), atomic_long_fetch_dec_acquire(9),
atomic_long_fetch_dec_release(9), atomic_long_fetch_dec_relaxed(9),
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), 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),
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_acquire(9), atomic_long_try_cmpxchg_release(9),
atomic_long_try_cmpxchg_relaxed(9), 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)

like I said. everyone. the whole friend group 🫶

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k bye bestie, that's the page!! 💜 this one's from ./include/linux/atomic and it's dated October 2026 — go forth and decrement responsibly, mwah 😭💖🧚