nlm4svc_proc_cancel_msg(9)

📦 version 7.3.1, in nixpkgs unstable

💅 nlm4svc_proc_cancel_msg — the kernel API manual, bestie edition ✨

Okay so we're diving into nlm4svc_proc_cancel_msg(9) today and honestly? It's giving "small function, big responsibilities." This is a Kernel API Manual entry, and the name literally tells you everything: CANCEL_MSG: Cancel an outstanding lock request 🎀

Like, somebody out there has a lock they don't want anymore, and this function is the one who picks up the phone. Iconic behavior, no cap.

✨ SYNOPSIS ✨

__be32 nlm4svc_proc_cancel_msg (struct svc_rqst *rqstp );

That's it. That's the whole signature. One argument, returns a __be32. Minimalist queen 🦋

🌸 ARGUMENTS 🌸

  • rqstp — the RPC transaction context, aka the whole vibe of the request that just showed up 💖

That's the only thing you hand it. One parameter, and it handles the rest.

🌈 RETURN 🌈

So like, what comes back? Two possibilities, and they're both rpc_success or rpc_system_err coded into that __be32 return value:

  • rpc_success — RPC executed successfully. Slay, it worked 💅
  • rpc_system_err — RPC execution failed. Not slay. Something went wrong 😭
Heads up bestie: the manual doesn't say what triggers which one beyond that, so don't go reading vibes into it — it just tells you those are the two outcomes. 🫶

🧚 DESCRIPTION 🧚

Okay so the technical bit, and yes I'm gonna give it to you straight:

RPC synopsis: void NLMPROC4_CANCEL_MSG(nlm4_cancargs) = 8;

That's the procedure number right there: 8. Lock it in your memory 🎀

And here's the important part — the actual answer doesn't come back from this call. Nope! The response to this request is delivered via the CANCEL_RES procedure. So this is like the "received your message, will reply later" of RPC procedures. Main character energy where the reply happens off-screen ✨

👑 SEE ALSO 👑

The kernel file involved is ./fs/lockd/svc4proc.c, and here's the whole friend group — every single one of them, no gatekeeping:

Go read them all, iykyk 🔥

And that's the page, bestie — brought to you from ./fs/lockd, dated October 2026, in the Kernel API Manual. Go forth and cancel those locks responsibly 💜🦋🌸

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