kho_radix_add_key(9)

✨ NAME ✨

This page is kho_radix_add_key(9) from the Kernel API Manual — yes bestie, the manual name is literally in the title vibe. 💅

kho_radix_add_key — add a key to the radix tree. Slay.

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🌸 SYNOPSIS 🌸

Okay so here's the whole signature at a glance:

int kho_radix_add_key (struct kho_radix_tree *tree , unsigned long key
);

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🎀 ARGUMENTS 🎀

Two things go in, bestie:

• tree — The KHO radix tree.
• key — The key to add.

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🦋 DESCRIPTION 🦋

Okay so here's the lore: this function traverses the radix tree based on the key provided. It sets the corresponding bit in the leaf bitmap to mark the key as present. If intermediate nodes do not exist along the path, they are allocated and added to the tree. It's giving “walk the path, flip the bit, build missing nodes” energy. 🦋

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💀 NOTE 💀

⚠️ Currently only keys of width up to KHO_RADIX_KEY_WIDTH are supported. This limit only exists because current users of the radix tree don't use more than that. Changing the maximum width requires changing the tree depth, which needs bumping the ABI version. So yeah — that's the rule, and it's not just a vibe. 💀

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🌈 RETURN 🌈

0 on success, or a negative error code on failure. Simple as that. ✨

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👑 SEE ALSO 👑

Kernel file ./kernel/liveupdate/kexec_handover.c — yes, that's the spot.

Also these iconic functions, no cap:

• kho_encode_radix_key(9)
• kho_decode_radix_key(9)
• kho_radix_del_key(9)
• kho_radix_init_tree(9)
• kho_radix_destroy_tree(9)
• kho_radix_walk_tree(9)
• kho_restore_folio(9)
• kho_restore_pages(9)
• kho_reserve_scratch(9)
• kho_add_subtree(9)
• kho_preserve_folio(9)
• kho_unpreserve_folio(9)
• kho_preserve_pages(9)
• kho_unpreserve_pages(9)
• kho_preserve_vmalloc(9)
• kho_unpreserve_vmalloc(9)
• kho_restore_vmalloc(9)
• kho_alloc_preserve(9)
• kho_unpreserve_free(9)
• kho_restore_free(9)
• is_kho_boot(9)
• kho_retrieve_subtree(9)

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byeee 🫶 source/version: ./kernel/liveupdate · date: October 2026 · page: kho_radix_add_key(9) — periodt.