irq_set_thread_affinity(9)

💖 irq_set_thread_affinity(9) 💖

okay bestie, this is the irq_set_thread_affinity(9) page from the Kernel API Manual, and it's literally about giving irq threads a lil nudge so they fix their own affinity. no cap, it's short and iconic. ✨

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🌸 NAME 🌸

irq_set_thread_affinity — the function that notifies irq threads to adjust affinity 💅

🎀 SYNOPSIS 🎀

the whole signature is giving one-line main character energy:

void irq_set_thread_affinity (struct irq_desc *desc );

🦋 ARGUMENTS 🦋

• desc — the irq descriptor whose affinity has changed, periodt 👑

✨ DESCRIPTION ✨

okay so the strategy is: just set IRQTF_AFFINITY and delegate the affinity setting to the interrupt thread itself. it's giving "you handle it, bestie" 🫶

we literally can not call set_cpus_allowed_ptr here because we're holding desc->lock, and this code can be called from hard interrupt context. so yeah, that's the whole reason — no cap. 😭

bestie, this is not the place to call set_cpus_allowed_ptr. the lock + hard-interrupt-context combo is the whole vibe check here. 💅

🌈 SEE ALSO 🌈

Kernel file: ./kernel/irq/manage.c — and the whole squad is:

• synchronize_hardirq(9)
• synchronize_irq(9)
• irq_can_set_affinity(9)
• irq_can_set_affinity_usr(9)
• irq_affinity_schedule_notify_work(9)
• irq_update_affinity_desc(9)
• irq_set_affinity(9)
• irq_force_affinity(9)
• irq_set_affinity_notifier(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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okay that's the whole page, bye bestie 🫶 this one comes from source ./kernel/irq, dated October 2026, and it's all about irq_set_thread_affinity(9). mwah 💋