test_and_clear_bit(9)

💅 test_and_clear_bit(9) 💅

okay so bestie, welcome to the Kernel API Manual — this one's a little kernel function called test_and_clear_bit, and honestly? she's iconic. ✨

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🌸 NAME 🌸

test_and_clear_bit — clear a bit and return its old value. that's it. that's the whole vibe. 🎀

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🦋 SYNOPSIS 🦋

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

like, she takes two things and gives you back a bool. main character energy. 👑

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🍓 ARGUMENTS 🍓

• nr — the bit you wanna clear. yes, this one. this is the bit. 🫶
• addr — the address to count from. that's where the counting happens. no cap. 💫

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🔥 DESCRIPTION 🔥

so here's the tea: this is an atomic, fully-ordered operation — meaning it comes with an implied full memory barrier. like, she's not just clearing a bit, she's doing it atomically AND respecting the full ordering. the way that she's both 😭🔥

bestie pls remember: atomic + fully ordered = no sneaky reordering shenanigans. the memory barrier is implied, so you don't gotta ask for it, she just comes with it. periodt. 💅

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🧚 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_change_bit(9)

the whole bitops friend group!! go say hi to all of them, they're all slay in their own way 🌈💜

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okay that's the whole page!! 🎀 this lil beauty lives in ./include/asm-generic/bitops and it's dated October 2026 — so like, future vibes only. mwah 💋✨ go clear some bits, bestie, you got this 🫶💖