test_and_change_bit(9)

✨ NAME ✨

okay so bestie, welcome to the Kernel API Manual — this is test_and_change_bit(9) 💅

test_and_change_bit — Change a bit and return its old value. literally the “glow up the bit, then tell you what it was before” of bit ops ✨

🦋 SYNOPSIS 🦋

bool test_and_change_bit (long nr , volatile unsigned long *addr );

🎀 ARGUMENTS 🎀

• nr — Bit to change 🫶
• addr — Address to count from. yes, that’s the official wording, iykyk 👑

🔥 DESCRIPTION 🔥

This is an atomic fully-ordered operation (implied full memory barrier). periodt. It’s giving serious synchronization energy, so treat it with main-character respect 💅✨

🌈 SEE ALSO 🌈

• Kernel file ./include/asm-generic/bitops/instrumented-atomic.h 🧚
• set_bit(9)
• clear_bit(9)
• change_bit(9)
• test_and_set_bit(9)
• test_and_clear_bit(9)

okay that’s the whole page, bestie 🫶 this cutie comes from the ./include/asm-generic/bitops source/version, dated October 2026, and it’s filed under test_and_change_bit(9). slay 💖