atomic_long_cmpxchg_relaxed(9)

💅 atomic_long_cmpxchg_relaxed(9) 💅

okay so welcome to the Kernel API Manual, bestie 🫶 — today’s main character is atomic_long_cmpxchg_relaxed(9), and she is literally here to do an atomic compare and exchange with relaxed ordering. no cap. ✨

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💖 NAME 💖

atomic_long_cmpxchg_relaxed — atomic compare and exchange with relaxed ordering. 🎀

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✨ SYNOPSIS ✨

long atomic_long_cmpxchg_relaxed (atomic_long_t *v , long old , long new
);

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🫶 ARGUMENTS 🫶

• v — pointer to atomic_long_t 💅
• old — long value to compare with 👀
• new — long value to assign ✨

---

🌸 DESCRIPTION 🌸

okay so here’s the plot: if (v == old), it atomically updates v to new with relaxed ordering. otherwise, v is not modified and relaxed ordering is provided. that’s the whole vibe. 🦋

🚨 no cap warning: this is unsafe to use in noinstr code. use raw_atomic_long_cmpxchg_relaxed there instead. don’t make it weird. 💀

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🎀 RETURN 🎀

the original value of v. it’s giving time traveler — you get the old value back. ⭐

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🦋 SEE ALSO 🦋

bestie the SEE ALSO section is a whole group chat. the kernel file is ./include/linux/atomic/atomic-instrumented.h, and here’s everyone invited, names preserved exactly:

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(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_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_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_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)

that’s the whole page, bestie 💖 — source/version: ./include/linux/atomic; date: October 2026; and yes, we’re still on atomic_long_cmpxchg_relaxed(9). periodt. ✨