test_and_set_bit_lock(9)

💅 test_and_set_bit_lock(9) 💅

okay so welcome to the Kernel API Manual corner, bestie — this page is literally about test_and_set_bit_lock, and it's giving tiny atomic bit-lock icon energy. ✨

🌸 NAME 🌸

test_and_set_bit_lock — sets a bit, returns its old value, and it's for lock. That's the whole vibe: set the bit, hand back what was there before, lock-style. Periodt. 💅

🦋 SYNOPSIS 🦋

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

Lowkey just keep that signature exactly as-is, because every character matters here. 🫶

🎀 ARGUMENTS 🎀

• nr — bit to set. You're picking the bit, bestie. 💖
• addr — address to count from. Yes, that's literally the description; no cap. 🙈

🔥 DESCRIPTION 🔥

This operation is atomic and provides acquire barrier semantics if the returned value is 0. That "if" is doing main-character work, so don't sleep on it. 😭

It can be used to implement bit locks. Iconic. 💅

🌈 SEE ALSO 🌈

• Kernel file ./include/asm-generic/bitops/instrumented-lock.h — the source-file bestie for this one. 🧚
• clear_bit_unlock(9)
• __clear_bit_unlock(9)
• xor_unlock_is_negative_byte(9)

mwah 💋 this page comes from ./include/asm-generic/bitops, dated October 2026, and it's part of the Kernel API Manual. Go set that bit, bestie — atomic and cute. 🎀✨