arch_test_and_set_bit(9)

okay so bestie, welcome to the arch_test_and_set_bit(9) page from the Kernel API Manual — yes, this is the bit-flipping baddie you were looking for, and it's lowkey iconic. let's get into it 💅✨

🌸 NAME 🌸

arch_test_and_set_bit — set a bit and return its old value. that's the whole vibe: you set one bit, and it hands you back what was there before. periodt.

✨ SYNOPSIS ✨

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

🎀 ARGUMENTS 🎀

• nr — the bit to set, fr fr. this is the one you're flipping.
• addr — the address to count from, no cap.

🔥 DESCRIPTION 🔥

This is an atomic, fully-ordered operation — and yes bestie, that means it has an implied full memory barrier. the ordering is part of the package 💖

atomic + fully ordered + implied full memory barrier = the whole mood. don't sleep on it.

🦋 SEE ALSO 🦋

Kernel file: ./arch/riscv/include/asm/bitops.h

The whole reference squad:

• __ffs(9)
• __fls(9)
• ffs(9)
• fls(9)
• arch_test_and_clear_bit(9)
• arch_test_and_change_bit(9)
• arch_set_bit(9)
• arch_clear_bit(9)
• arch_change_bit(9)
• arch_test_and_set_bit_lock(9)
• arch_clear_bit_unlock(9)
• arch___clear_bit_unlock(9)

mwah 💋 this cutie comes from ./arch/riscv/include/asm, and the manual page is dated October 2026. bye bestie, go set some bits responsibly 🫶✨