msi_for_each_desc(9)

💅 msi_for_each_desc(9) — a lil' field guide from the Kernel API Manual 🎀

okay so bestie, picture this: you're deep in ./include/linux/msi.h and you need to walk every single MSI descriptor in the default irqdomain. that's it. that's the whole vibe of this macro. lowkey iconic, highkey essential 🦋

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✨ NAME ✨

msi_for_each_desc — iterate the MSI descriptors in the default irqdomain 🌀

like, a lil' for-loop but make it kernel. main character energy fr fr.

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🌸 SYNOPSIS 🌸

msi_for_each_desc (desc , dev , filter );

that's the whole thing. three args, no cap. copy it exactly like that, spacing and all, she's picky 💅

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🧚 ARGUMENTS 🧚

• desc — a struct msi_desc pointer that you're using as the iterator. she's the lil' cursor that hops from descriptor to descriptor, one at a time, minding her own business 🐾
• dev — a struct device pointer, i.e. the device you're iterating over. this is the "who am I looking at" of the whole operation 👀
• filter — the filter for descriptor selection. yeah, you get to be picky about which descriptors show up to the party — filter decides who makes the guest list 🎟️

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🔥 NOTES 🔥

okay this part is NOT optional, bestie. read it twice. 🚨

• the loop must be protected with a msi_lock_descs/msi_unlock_descs pair. like, lock first, unlock after. do not skip this. do not "forget". do not "it'll probably be fine". it will not be fine 💀
• it is safe to remove a retrieved MSI descriptor in the loop. yes, inside the loop, while you're iterating. go off king, delete her mid-stride 👑✨ — that one's actually sanctioned, unlike the lock thing.

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🦋 SEE ALSO 🦋

the whole squad, gathered for you, in the kernel file ./include/linux/msi.h:

• struct msi_msg(9)
• struct pci_msi_desc(9)
• union msi_domain_cookie(9)
• struct msi_desc_data(9)
• struct msi_desc(9)
• struct msi_dev_domain(9)
• msi_first_desc(9)
• msi_domain_for_each_desc(9)
• msi_msg_set_addr(9)
• msi_insert_msi_desc(9)
• msi_free_msi_descs_range(9)
• msi_free_msi_descs(9)
• struct msi_domain_ops(9)
• struct msi_domain_info(9)
• struct msi_domain_template(9)
• struct msi_parent_ops(9)

not me listing all sixteen of them because every single one matters 💖

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and that's the page!! this lil' gem lives under ./include/linux, dated October 2026, straight from the Kernel API Manual — catch you on the next loop iteration, bestie 🫶💜