irq_set_affinity_notifier(9)

💅 irq_set_affinity_notifier(9) — the irq_set_affinity_notifier page, bestie edition 🎀

okay so this is a Kernel API Manual page, the function lives in section 9, and honestly? it's a little baddie. let's get into it ✨

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🌸 NAME 🌸

irq_set_affinity_notifier — control notification of IRQ affinity changes 💫

like, it's the girl who tells you when your IRQ's affinity changed. she's the notifier. she notifies. periodt.

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✨ SYNOPSIS ✨

int irq_set_affinity_notifier (unsigned int irq , struct
irq_affinity_notify *notify );

that's it. that's the whole signature. two args, one int coming back at you 🫶

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🦋 ARGUMENTS 🦋

• irq — the interrupt you're enabling/disabling notification for. it's giving "main character interrupt" ngl, everything's about her 💅
• notify — the context for notification, or NULL to disable notification. ⚠️ and listen: the function pointers must be initialised by you. the other fields? this function handles those, she'll set them up for you. you just do the pointers, she does the rest. teamwork fr fr 🫶

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💖 DESCRIPTION 💖

must be called in process context. no exceptions, bestie. 😭

and here's the timeline, write it down:

• notification may only be enabled after the IRQ is allocated ✨
• and it must be disabled before the IRQ is freed using free_irq 💀

like... enable after allocate, disable before free. it's giving boundaries. respect the boundaries 🙈

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🌈 SEE ALSO 🌈

the whole friend group, okay, they all hang out together:

• kernel file ./kernel/irq/manage.c — that's where she lives 🏠
• synchronize_hardirq(9)
• synchronize_irq(9)
• irq_can_set_affinity(9)
• irq_can_set_affinity_usr(9)
• irq_set_thread_affinity(9)
• irq_affinity_schedule_notify_work(9)
• irq_update_affinity_desc(9)
• irq_set_affinity(9)
• irq_force_affinity(9)
• irq_set_vcpu_affinity(9)
• disable_irq_nosync(9)
• disable_irq(9)
• disable_hardirq(9)
• disable_nmi_nosync(9)
• enable_irq(9)
• enable_nmi(9)
• irq_set_irq_wake(9)
• irq_wake_thread(9)
• free_irq(9)
• request_threaded_irq(9)
• request_any_context_irq(9)
• request_nmi(9)
• irq_percpu_is_enabled(9)
• free_percpu_irq(9)
• request_percpu_irq_affinity(9)
• request_percpu_nmi(9)
• prepare_percpu_nmi(9)
• teardown_percpu_nmi(9)
• irq_get_irqchip_state(9)
• irq_set_irqchip_state(9)
• irq_has_action(9)
• irq_check_status_bit(9)

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and that's the page!! 🎀 this iconic little number comes from ./kernel/irq and it's dated October 2026 — so she's from the future, lowkey a time traveler 👑💜 stay safe, init your function pointers, and free your IRQs after you disable the notifier. mwah 💋