Re: [PATCH v1 5/5] svcrdma: release a receive context stranded by a partial Read post

[sashiko-bot@kernel.org]

> When ib_post_send() rejects a WR mid-chain, svc_rdma_post_send_err()
> returns zero and svc_rdma_post_chunk_ctxt() reports the Read chain
> as posted. The only signaled WR in the chain is its tail, so a chain
> cut before the tail posts nothing that completes.
> svc_rdma_process_read_list() then reports the Read in progress, and
> the receive context waits for svc_rdma_wc_read_done(), which never
> runs. No list the transport destructor walks holds the context, so
> it leaks past teardown along with its rw contexts and their DMA
> mappings.
> 
> The caller cannot release the context on the error, because the
> posted Read WRs still write into pages it owns. Nor can the error
> path drain the Send Queue. The drain's marker WR needs an SQ slot,
> and a provider that has just rejected a WR cannot be trusted to
> have one.
> 
> Park the receive context on a per-transport list, as the Send path
> does, and release it from svc_rdma_free() after the drain and before
> the rw contexts are destroyed. svc_rdma_post_chunk_ctxt() posts only
> Read chains, so pass it the receive context itself rather than the
> embedded chunk context.
> 
> Reaching this path needs a provider to reject a WR after accepting
> earlier ones in the same chain. That has not been observed.
> 
> Fixes: f13193f50b64 ("svcrdma: Introduce local rdma_rw API helpers")
> Signed-off-by: Chuck Lever <cel@kernel.org>

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

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Sashiko AI review · https://sashiko.dev/#/patchset/20260922015128.240977-1-cel@kernel.org?part=5