INTR_BARRIER(9)

💅 INTR_BARRIER — interrupt barrier, bestie

okay so bestie, welcome to intr_barrier — it's a kernel thing (the man page lives in section 9 of the Kernel Developer's Manual, iykyk), and honestly? she's lowkey iconic for how much she does with so little.

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🌸 NAME 🌸

intr_barrier — interrupt barrier ✨

Like, a barrier. For interrupts. That's the whole vibe. 🎀

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🦋 SYNOPSIS 🦋

#include <machine/intr.h>

void
intr_barrier(void *ih);

that's it. that's the whole signature. no cap. 🫶

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💖 DESCRIPTION 💖

okay so here's the tea, and it is good tea. ☕

intr_barrier() guarantees that any interrupt handler invocations for the interrupt handler specified by ih have finished before it returns. literally — every single invocation, done, wrapped, finished, no stragglers, before this function hands control back to you. periodt. 💅

and the way that ih works is: the cookie you pass to intr_barrier() should be the value returned when the interrupt handler was established — for example, the return value of pci_intr_establish(9). so like, don't just make up a cookie, bestie. use the one they gave you. 🙈

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🔥 CONTEXT 🔥

so like, where can you even call this? good news:

intr_barrier() can be called from process context. 🫶

that's the whole section. she's short but she ate. 👑

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🎀 SEE ALSO 🎀

go read these next, they're friends of hers:

• pci_intr_establish(9) — where your ih cookie comes from in the first place 💖
• spl(9) — the other classic interrupt-adjacent baddie ✨

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⚠️ friendly reminder: pass the actual cookie from when the handler was established. a random pointer is not giving what you think it's giving. 💀

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and that's the whole page, bestie!! this lil slice of kernel lore is brought to you by Debian, dated September 13, 2015 — yeah she's vintage, she's a classic, she's still serving. 🌈💜 go forth and barrier your interrupts responsibly. mwah. 🍓