rc_rcv_error(9)

📦 version 7.3.1, in nixpkgs unstable

🌸 rc_rcv_error — process an incoming duplicate or error RC packet 🌸

okay so bestie, we're deep in the kernel today. the manual name is rc_rcv_error(9) and yeah, she's a section 9 girlie — kernel API, no cap. this is the function that handles the messy packets nobody else wants to deal with 💅

✨ SYNOPSIS ✨

int rc_rcv_error (struct ib_other_headers *ohdr , void *data , struct
       rvt_qp *qp , u32 opcode , u32 psn , int diff , struct hfi1_ctxtdata *rcd
       );

she returns an int, she takes seven args, and she does not do small talk 🫶

🎀 ARGUMENTS 🎀

  • ohdr — the other headers for this packet. like, the headers that aren't THE header, yk? the other ones 💖
  • data — the packet data. the main character payload, lowkey ✨
  • qp — the QP for this packet. that's the queue pair this whole situation belongs to 👑
  • opcode — the opcode for this packet. literally what kind of packet we're dealing with 🔥
  • psn — the packet sequence number for this packet. the receipts, fr fr 🧾
  • diff — the difference between the PSN and the expected PSN. someone's out of sync and we're measuring exactly how much 😭
  • rcd — the receive context. the whole vibe she's operating in 🌈

💜 DESCRIPTION 💜

so this one gets called from hfi1_rc_rcv to process an unexpected incoming RC packet for the given QP. unexpected!! the audacity!! 🙈

heads up bestie: this runs at interrupt level. no sleeping, no vibing, no long conversations. in and out, periodt ⚡

the return value is giving binary decisions:

  • return 1 if no more processing is needed — we're done here, bye bestie 👋
  • otherwise return 0 to schedule a response to be sent — like, we gotta reply, so we're handing that off 📬

that's it. that's the whole flow. simple but iconic 💅

🦋 SEE ALSO 🦋

kernel file ./drivers/infiniband/hw/hfi1/rc.c, and the whole friend group:

🌸 okay that's the page!! this one lives in ./drivers/infiniband/hw/hfi1, the date on it is October 2026, and the header/footer both say rc_rcv_error(9) — so if you cite her, cite her properly. mwah 💋✨

📦 where this page comes from