rpcrdma_sendctx_get_locked(9)

📦 version 7.3.1, in nixpkgs unstable

💅 rpcrdma_sendctx_get_locked(9) — a Kernel API Manual moment

okay so bestie, we're in the Kernel API Manual today and the star of the show is rpcrdma_sendctx_get_locked — yes that's a whole mouthful, yes it's iconic, no we're not skipping any of it. let's get into it 🫶

✨ NAME ✨

rpcrdma_sendctx_get_locked — Acquire a send context 🌸

like, literally go get yourself a send context. that's the whole vibe.

🦋 SYNOPSIS 🦋

struct rpcrdma_sendctx * rpcrdma_sendctx_get_locked (struct rpcrdma_xprt *r_xprt );

she takes exactly one thing and she gives you back a pointer. periodt.

🎀 ARGUMENTS 🎀

  • r_xprt — the controlling transport instance 💖 (the main character, honestly — everything happens around her)

🔥 DESCRIPTION 🔥

So what does she actually do? She returns a pointer to a free send completion context. that's it, that's the job. no cap. ✨

But — and this is the part where you gotta pay attention — if the queue is empty, she returns NULL. not an error code, not a vibe, just NULL. 😭 so check that pointer, bestie, fr fr.

Usage: she's called to acquire an SGE array before preparing a Send WR. like, you grab the array first, then you do the Send WR thing. order matters. iykyk.

And now the lowkey serious bit 👑 — the caller serializes calls to this function (per transport), and provides an effective memory barrier that flushes the new value of rb_sc_head.

🫶 real talk: that serialization + memory barrier thing is on you, the caller. she's not doing it for you. that's the deal. keep it locked (the name literally says _locked, she's telling you something 💅).

🌈 SEE ALSO 🌈

Kernel file ./net/sunrpc/xprtrdma/verbs.c — and the whole friend group 🦋:

go read them all, they're all slay, i don't make the rules 💜

and that's the page, bestie!! 🎀 sign-off time: this one lives in ./net/sunrpc/xprtrdma, dated October 2026, and it's rpcrdma_sendctx_get_locked(9) through and through. mwah. 💋🌸

📦 where this page comes from