vdo_launch_c...ion_callback(9)

📦 version 7.3.1, in nixpkgs unstable

💅 vdo_launch_c...ion_callback(9) — from the Kernel API Manual ✨

Okay bestie, listen up, because we're about to read a kernel manpage together and honestly? It's giving mystery. The page you're looking at is literally titled vdo_launch_c...ion_callback(9) (yes, that's the real, truncated-as-heck header, and no, we are not fixing it — it's iconic, it stays) and it lives in the Kernel API Manual. Pull up a chair. 🫶

✨ NAME ✨

vdo_launch_completion_callback — sets the callback for a completion and launches it immediately.

That's it. That's the whole vibe. It sets the callback and launches it right away, no waiting around, no "let me think about it", zero hesitation, main character energy only. 💅

🌸 SYNOPSIS 🌸

void vdo_launch_completion_callback (struct vdo_completion *completion ,
vdo_action_fn callback , thread_id_t callback_thread_id );

So it returns void (nothing comes back, it just does the thing), and it takes three things: a completion, a callback, and a callback_thread_id. Look at that signature slaying in its natural habitat. 🦋

🎀 ARGUMENTS 🎀

Okay so this is where it gets a little unhinged, because the original page simply did not describe these. Not even a little. Every single one of them is marked -- undescribed --. I'm not making this up, I'm not being lazy — that's genuinely what the page says, so that's genuinely what you get. Ngl, the manpage left us on read. 😭

  • completion — -- undescribed -- literally, bestie. It's a struct vdo_completion * in the synopsis, and the description is quite simply not there. It's giving mysterious. 🙈
  • callback — -- undescribed -- again. Type is vdo_action_fn in the synopsis. Beyond that? The page says nothing. A whole callback, undiscussed. 💀
  • callback_thread_id — -- undescribed --, one more time, of type thread_id_t. The thread id where the callback goes, presumably by the name, but the page itself is not about to confirm anything for us. It said what it said, which is nothing. ⭐
Fr fr though: I will not invent details here. The original marks all three arguments as -- undescribed --, so all three arguments are, in fact, undescribed. Do not come for me, come for the doc. 💖

🦋 SEE ALSO 🦋

Kernel file ./drivers/md/dm-vdo/completion.h — that's the header where the friends live — plus this whole little friend group right here:

The way that's a whole completion squad — run, reset, launch, continue, fail, assert, prepare, prepare-for-requeue. Obsessed. Go read them all, iykyk. 👑

And that's the page, bestie! 🌈 This little slice of documentation lives in ./drivers/md/dm-vdo, dated October 2026, and it goes out under the exact same truncated header it came in with, vdo_launch_c...ion_callback(9). Periodt. 🎀✨

📦 where this page comes from