msi_next_desc(9)

✨ msi_next_desc ✨

Okay bestie, welcome to msi_next_desc(9) from the Kernel API Manual — literally the "gimme the next one" function for MSI descriptors, and she is very particular about how you call her. 🎀

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💜 NAME 💜

msi_next_desc — get the next MSI descriptor of a device. That's it, that's the whole vibe. 🦋

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🌸 SYNOPSIS 🌸

struct msi_desc * msi_next_desc (struct device *dev , unsigned int domid , enum msi_desc_filter filter );

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👑 ARGUMENTS 👑

• dev — the device you're operating on. Your main character. 💅
• domid — the id of the interrupt domain that should be walked. Like, which neighborhood we're strolling through.
• filter — the descriptor state filter. This is the vibe check: only descriptors matching your criteria get to come through. ✨

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🔥 DESCRIPTION 🔥

Okay so here's the tea, and you need to hear it. ☕

The first time you call msi_next_desc, you must have already called __msi_first_desc successfully first — no cap. Like, you can't just show up to the function without an invitation. Consecutive invocations are only valid if the previous one was successful. So it's a chain: if a link breaks, the whole thing breaks, and that's on you. 😭

And the biggest rule of all: all of these operations have to be done within the same MSI mutex held region. Same region, bestie. Don't be out here unlocking mid-walk. That's giving undefined behavior energy and we do not stan. 💀

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🌈 RETURN 🌈

A pointer to the next MSI descriptor that matches the search criteria. 🫶 And if nothing matches? You get NULL. None found, no descriptor, go home. 🙈

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⭐ SEE ALSO ⭐

Kernel file ./kernel/irq/msi.c, plus this whole squad right here — she keeps good company:

• struct msi_device_data(9)
• struct msi_ctrl(9)
• msi_alloc_desc(9)
• msi_domain_insert_msi_desc(9)
• msi_domain_free_msi_descs_range(9)
• msi_domain_add_simple_msi_descs(9)
• msi_setup_device_data(9)
• __msi_lock_descs(9)
• __msi_unlock_descs(9)
• msi_domain_first_desc(9)
• msi_domain_get_virq(9)
• msi_device_populate_sysfs(9)
• msi_device_destroy_sysfs(9)
• msi_domain_set_affinity(9)
• msi_create_irq_domain(9)
• msi_create_parent_irq_domain(9)
• msi_parent_init_dev_msi_info(9)
• msi_create_device_irq_domain(9)
• msi_remove_device_irq_domain(9)
• msi_match_device_irq_domain(9)
• msi_domain_alloc_irqs_range_locked(9)
• msi_domain_alloc_irqs_range(9)
• msi_domain_alloc_irqs_all_locked(9)
• msi_domain_alloc_irq_at(9)
• msi_device_domain_alloc_wired(9)
• msi_domain_free_irqs_range_locked(9)
• msi_domain_free_irqs_range(9)
• msi_domain_free_irqs_all_locked(9)
• msi_domain_free_irqs_all(9)
• msi_device_domain_free_wired(9)
• msi_get_domain_info(9)
• msi_device_has_isolated_msi(9)

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Sources say this one lives in ./kernel/irq and got her glow-up in October 2026 — go off, queen. 👑✨ Slay, and remember: lock the mutex. 🫶💖