vringh_getdesc_kern(9)

🌸 vringh_getdesc_kern(9) — Kernel API Manual realness 🌸

Okay bestie, so this is vringh_getdesc_kern(9) from the Kernel API Manual, and it's literally the function that grabs the next available descriptor from a kernelspace ring. No cap, it's giving "main character energy" in the vringh kernel squad. 💅✨

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✨ NAME ✨

vringh_getdesc_kern — get next available descriptor from kernelspace ring.

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🦋 SYNOPSIS 🦋

int vringh_getdesc_kern (struct vringh *vrh , struct vringh_kiov *riov ,
struct vringh_kiov *wiov , u16 *head , gfp_t gfp );

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🎀 ARGUMENTS 🎀

• vrh — the kernelspace vring. That's your main character right there. 👑
• riov — where to put the readable descriptors (or NULL if you're not about that life).
• wiov — where to put the writable descriptors (or NULL, same vibe).
• head — the head index we received, for passing to vringh_complete_kern. Don't lose it, bestie.
• gfp — flags for allocating larger riov/wiov. Like, if the ring needs more room, this tells the allocator how to act.

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💖 DESCRIPTION 💖

Returns 0 if there was no descriptor, 1 if there was, or -errno. So like, 0 = nothing, 1 = slay, -errno = something went sideways. 😭

Note that on error return, you can tell the difference between an invalid ring and a single invalid descriptor: in the former case, *head will be vrh->vring.num. You may be able to ignore an invalid descriptor, but there's not much you can do with an invalid ring. 💀

Also, you can reuse riov and wiov with subsequent calls. Content is overwritten and memory reallocated if more space is needed. It's giving "sustainable queen" energy. 🌱

When you don't have to use riov and wiov anymore, you should clean up them calling vringh_kiov_cleanup to release the memory, even on error! Like, do not skip this, fr fr. 🫶

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🌈 SEE ALSO 🌈

Kernel file ./drivers/vhost/vringh.c and these iconic functions, iykyk:

• vringh_kiov_advance(9)
• vringh_init_user(9)
• vringh_getdesc_user(9)
• vringh_iov_pull_user(9)
• vringh_iov_push_user(9)
• vringh_complete_user(9)
• vringh_complete_multi_user(9)
• vringh_notify_enable_user(9)
• vringh_notify_disable_user(9)
• vringh_need_notify_user(9)
• vringh_init_kern(9)
• vringh_complete_kern(9)
• vringh_notify_enable_kern(9)
• vringh_notify_disable_kern(9)
• vringh_need_notify_kern(9)
• vringh_init_iotlb(9)
• vringh_init_iotlb_va(9)
• vringh_set_iotlb(9)
• vringh_getdesc_iotlb(9)
• vringh_iov_pull_iotlb(9)
• vringh_iov_push_iotlb(9)
• vringh_complete_iotlb(9)
• vringh_need_notify_iotlb(9)

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This page lives in ./drivers/vhost, dated October 2026, and it's all about vringh_getdesc_kern(9). Bye bestie, go get those descriptors! 💜🧚‍♀️