hwspin_lock_timeout_irq(9)

📦 version 7.3.1, in nixpkgs unstable

💅 hwspin_lock_timeout_irq(9) — from the Kernel API Manual, bestie

okay so real talk, this is a page straight out of the Kernel API Manual and it's about grabbing a hardware spinlock without letting your whole world hang forever. she waits, but she has boundaries. periodt.

✨ NAME ✨

hwspin_lock_timeout_irq — lock a hwspinlock, but with a timeout, and disable irqs while you're at it 🎀

✨ SYNOPSIS ✨

int hwspin_lock_timeout_irq (struct hwspinlock *hwlock , unsigned int to );

✨ ARGUMENTS ✨

  • hwlock — the hwspinlock you're trying to lock, like the door you wanna get through 🚪
  • to — the timeout value, and it's in msecs (milliseconds, not vibes) ⏱️

🌸 DESCRIPTION 🌸

So this function locks the underlying hwlock. simple enough, right?

But here's the tea: if the hwlock is already taken, she doesn't just give up immediately — she busy loops, waiting for it to be released 🌀. The catch is she has a limit, and once to msecs have elapsed she's like "okay bestie I'm out" and gives up. no cap.

Upon a successful return from this function, preemption and local interrupts are disabled, so lowkey the caller must NOT sleep 😴🚫 — and you're advised to release the hwspinlock as soon as possible. like, don't sit on it. it's not a chair. 🪑💀

It returns 0 when the hwlock was successfully taken, and an appropriate error code otherwise — most notably an -ETIMEDOUT if the hwlock is still busy after to msecs 😭. And one more time for the people in the back: the function will never sleep. ever. not once. 🫶

🦋 SEE ALSO 🦋

The source lives in the kernel file ./include/linux/hwspinlock.h, and honestly the whole friend group is iconic:

⚠️ friendly reminder: successful return means preemption and local interrupts are off and you must not sleep. treat this lock like a hot potato, not a long-term relationship 💅🔥

okay that's the whole page, mwah 💖 — this one ships from ./include/linux, dated October 2026. go lock responsibly, bestie 🌈👑

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