arch___test_and_clear_bit(9)

💅 arch___test_and_clear_bit(9) — Kernel API Manual ✨

okay so bestie, buckle up, we're reading a kernel API manual page together and honestly? it's lowkey iconic. this is arch___test_and_clear_bit, straight out of the kernel API manual, and it's giving "tiny function, big responsibilities." 🎀

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🌸 NAME 🌸

arch___test_and_clear_bit — clear a bit and return its old value 🫶

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⭐ SYNOPSIS ⭐

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

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🦋 ARGUMENTS 🦋

• nr — the bit you want to clear, bestie. that's the one. 💅
• addr — the address to count from. yes, "count from," that's literally what it says, don't come for me. 🌈

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🔥 DESCRIPTION 🔥

okay so here's the tea, and it's important tea: this operation is non-atomic and can be reordered. not me warning you about race conditions twice in one sentence, but here we are. 😭

if two examples of this operation race, one can appear to succeed but actually fail. like??? imagine winning and then finding out you didn't win. the audacity. 💀

so no cap: you must protect multiple accesses with a lock. periodt. if you skip the lock, that's on you and the vibe check will not be kind. 🙈

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👑 SEE ALSO 👑

• Kernel file ./arch/sh/include/asm/bitops-op32.h — the literal source of truth, iykyk 📁
• arch___change_bit(9) — the cousin that changes bits ✨
• arch___test_and_set_bit(9) — the cousin that sets bits 🌸

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and that's the whole page, bestie! this one came from ./arch/sh/include/asm and it's dated October 2026, so like… remember it fondly. mwah 💖 🧚‍♀️ 🍓