dequeue_tid_waiter(9)

💅 dequeue_tid_waiter(9) — like, the Kernel API Manual era 🎀

okay so bestie, we're in the Kernel API Manual today and this one's about pulling a qp out of a list. yes it's a kernel function, no it's not scary, come sit with me 💖

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✨ NAME ✨

dequeue_tid_waiter — dequeue the qp from the list. that's it, that's the whole vibe 🫶

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🌸 SYNOPSIS 🌸

void dequeue_tid_waiter (struct hfi1_ctxtdata *rcd , struct tid_queue
*queue , struct rvt_qp *qp );

look at that signature, it's giving "three args and zero thoughts" 👑

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🦋 ARGUMENTS 🦋

• rcd — the receive context. the main character of this whole situation ngl
• queue — the queue we're operating on. the venue, if you will 🎀
• qp — the qp to remove from the wait list. the one getting un-invited from the group chat 🙈

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💜 DESCRIPTION 💜

so this routine removes the indicated qp from the wait list if it is there (conditional queen behavior, we love to see it ✨).

the timing? highkey matters. this should be done after the hardware flow and tid array resources have been allocated. like, resources first, dequeue second, no skipping steps bestie 😭

🚨 lock check, no cap: must hold the qp s_lock and the rcd exp_lock. both. not one, both. iykyk 💅

and the reason for the s_lock? it assumes the s_lock to protect the s_flags field and to reliably test the HFI1_S_WAIT_TID_SPACE flag. so yeah, the lock isn't decorative, it's doing real work fr fr 🔥

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🌈 SEE ALSO 🌈

in the kernel file ./drivers/infiniband/hw/hfi1/tid_rdma.c, and also go read up on:

• TID RDMA READ protocol(9)
• qp_to_rcd(9)
• lock ordering(9)
• kernel_tid_waiters(9)
• queue_qp_for_tid_wait(9)
• __trigger_tid_waiter(9)
• tid_rdma_schedule_tid_wakeup(9)
• tid_rdma_trigger_resume(9)
• kern_reserve_flow(9)
• tid_rdma_find_phys_blocks_4k(9)
• tid_flush_pages(9)
• tid_rdma_find_phys_blocks_8k(9)
• hfi1_kern_exp_rcv_setup(9)
• hfi1_kern_exp_rcv_free_flows(9)
• __trdma_clean_swqe(9)
• hfi1_schedule_tid_send(9)

that's the whole reading list, put it in your notes app 📝💖

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and that's a wrap, bestie! this iconic little page lives in ./drivers/infiniband/hw/hfi1, dated October 2026, and it's still signed off as dequeue_tid_waiter(9) — slay, stay hydrated, and always hold both locks 💅✨🍓