sdma_send_txreq(9)

💅 sdma_send_txreq(9) 💅

okay so bestie, this is a page from the Kernel API Manual — yes, the kernel kernel, we're literally in the guts of Linux rn, main character energy fr fr. This is sdma_send_txreq(9) and it's about yeeting a tx req into a ring. Stay with me, it slaps.

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✨ NAME ✨

sdma_send_txreq — submit a tx req to ring 🎀

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🌸 SYNOPSIS 🌸

int sdma_send_txreq (struct sdma_engine *sde , struct iowait_work *wait
, struct sdma_txreq *tx , bool pkts_sent );

like, look at that signature. so clean. so iconic. 🫶

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🦋 ARGUMENTS 🦋

• sde — the sdma engine you're gonna use, no cap. that's your engine.
• wait — the SE wait structure to use when it's full — and heads up, this one may be NULL. 🙈
• tx — the actual sdma_txreq you're submitting. the star of the show, the main character.
• pkts_sent — a bool that's literally just: has any packet been sent yet? yes/no, vibe check. ⭐

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💖 DESCRIPTION 💖

So the call submits the tx into the ring. That's the whole bit. 💅

And if an iowait structure is non-NULL, the packet gets queued to the list in wait — like it's waiting in the group chat for its turn to speak, iykyk. 🧚

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🔥 RETURN 🔥

here's the receipts, bestie — memorize these numbers, they matter 😭

• 0 — Success 🎉
• -EINVAL — sdma_txreq incomplete
• -EBUSY — no space in ring (wait == NULL)
• -EIOCBQUEUED — tx queued to iowait
• -ECOMM — bad sdma state 💀

not me listing every single one of these — yes, all of them, because you need all of them, periodt.

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🌈 SEE ALSO 🌈

• Kernel file ./drivers/infiniband/hw/hfi1/sdma.c
• sdma_state_name(9)
• sdma_get_descq_cnt(9)
• sdma_engine_get_vl(9)
• sdma_select_engine_vl(9)
• sdma_select_engine_sc(9)
• sdma_seqfile_dump_cpu_list(9)
• sdma_map_init(9)
• sdma_clean(9)
• sdma_init(9)
• sdma_all_running(9)
• sdma_start(9)
• sdma_exit(9)
• __sdma_txclean(9)
• sdma_engine_error(9)
• sdma_seqfile_dump_sde(9)
• sdma_send_txlist(9)
• sdma_ahg_alloc(9)
• sdma_ahg_free(9)
• _sdma_engine_progress_schedule(9)

like, that's the whole friend group right there. go say hi. 🫶✨

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mwah 💋 that's the page!! this one lives in ./drivers/infiniband/hw/hfi1 and it's dated October 2026 — so yeah, go read it, stan it, cite it in your patch. slay. 👑🌸