spin_event_timeout(9)

💅 spin_event_timeout(9) 💅

okay so bestie, this is a page from the Kernel API Manual and it's about spin_event_timeout — aka the little macro that spins until a condition gets true, or until a timeout elapses. whichever comes first. iconic behaviour honestly 🎀

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✨ SYNOPSIS ✨

spin_event_timeout (condition , timeout , delay );

like yes, three arguments, she's low maintenance 💖

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🫶 ARGUMENTS 🫶

• condition — a C expression to evalate. (yes that's a typo in the original, we're keeping it, she's part of the lore now 🙈 — it's the thing you want to be checked over and over)
• timeout — the timeout, measured in microseconds
• delay — the number of microseconds to delay between each evaluation of condition. like a little breather between checks, very self-care of her 🌸

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🌈 DESCRIPTION 🌈

So the process spins — like, literally sits there in a loop, no napping, no scheduling, just vibes and burning cycles 🔥 — until the condition evaluates to true (non-zero) or the timeout elapses. whichever hits first, periodt.

The return value of this macro is the value of condition when the loop terminates. that's so you can tell why the loop terminated, iykyk 👑. If the return value is zero, then you know a timeout has occurred. zero = timeout, that's the whole vibe check right there 💀

The primary purpose of this macro is to poll on a hardware register until a status bit changes. she's a poller, that's her job 🧚 The timeout ensures that the loop still terminates even if the bit never changes — so no infinite-loop girlbossing into a hang 😭. And the delay is for devices that need a delay in between successive reads. some hardware is shy, we respect that 🦋

⚠️ ngl this is a real one: gcc will optimize out the if-statement if delay is a constant. so don't be surprised when the compiler eats it — that's not a bug, bestie, that's the compiler doing her thing ⭐

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💜 SEE ALSO 💜

• Kernel file ./arch/powerpc/include/asm/delay.h

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okay that's the whole page, you ate that 🍓 this was brought to you by the source ./arch/powerpc/include/asm, dated October 2026 — and it's about to time out in 0 microseconds so go, run, read the header file 💅✨🫶