Re: [PATCH] RDMA/rtrs-clt: Fix recv repost to satisfy ib_drain_rq

[sashiko-bot@kernel.org]

> From: Quanye Yang <quanyeyang@proton.me>
> 
> On disconnect the client error recovery path calls ib_drain_qp(), which
> requires one free RQ slot and that no recv WQEs are posted while the
> queue is being drained.
> 
> The legacy recv completion path deferred reposting invalidate receives
> and instead posted two empty recv WQEs when handling RDMA-with-IMM
> responses marked with invalidation.  If an invalidate receive never
> arrived, each such response increased RQ occupancy by one until
> ib_post_recv() started returning -ENOMEM and __ib_drain_rq() failed with:
> 
>   failed to drain recv queue: -12
> 
> Repost one empty recv WQE for every receive completion, including legacy
> SEND_WITH_INV invalidates, and only while the path is still connected
> so CQ polling cannot race with ib_drain_qp().  Size IO connection RQs to
> 2 * queue_depth + 1 to match the posted recv count and leave the drain
> slot.
> 
> Tested with a synthetic RTRS client flooding unpaired
> RTRS_IO_RSP_W_INV_IMM messages; error recovery no longer triggers
> __ib_drain_rq() warnings.
> 
> Fixes: 6a98d71daea1 ("RDMA/rtrs: client: main functionality")
> Signed-off-by: Quanye Yang <quanyeyang@proton.me>

Sashiko has reviewed this patch and found no issues. It looks great!

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Sashiko AI review · https://sashiko.dev/#/patchset/20260921-rtrs-fix-ib-drain-rq-v1-1-11b1637958ba@proton.me?part=1