arch_test_and_set_bit_lock(9)

okay bestie, this is arch_test_and_set_bit_lock(9) from the Kernel API Manual, and it’s giving “set a bit, return the old value, lock edition” energy 💅✨

🌸 NAME 🌸

arch_test_and_set_bit_lock — set a bit and return its old value, for lock 🎀

✨ SYNOPSIS ✨

int arch_test_and_set_bit_lock (unsigned int nr , volatile unsigned long *addr );

🎀 ARGUMENTS 🎀

• nr — the bit to set, periodt 💖
• addr — the address to count from 🫶

🔥 DESCRIPTION 🔥

okay so here’s the tea: this operation is atomic 💥 and provides acquire barrier semantics if the returned value is 0. It can be used to implement bit locks 👑.

🦋 SEE ALSO 🦋

• Kernel file: ./include/asm-generic/bitops/lock.h
• arch_clear_bit_unlock(9)
• arch___clear_bit_unlock(9)

source/version: ./include/asm-generic/bitops · date: October 2026 · page: arch_test_and_set_bit_lock(9) — slay and goodnight, bestie 💜✨