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Subject: Re: [PATCH v2] nvme-rdma: handle nvme completion data length
To:     zhenwei pi <pizhenwei@bytedance.com>, kbusch@kernel.org,
        hch@lst.de, axboe@fb.com
Cc:     linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org
References: <20201023065910.1358586-1-pizhenwei@bytedance.com>
From:   Sagi Grimberg <sagi@grimberg.me>
Message-ID: <d23e33e7-d545-2ad0-d163-5182dd5430b1@grimberg.me>
Date:   Fri, 23 Oct 2020 11:01:40 -0700
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> diff --git a/drivers/nvme/host/rdma.c b/drivers/nvme/host/rdma.c
> index 9e378d0a0c01..2ecadd309f4a 100644
> --- a/drivers/nvme/host/rdma.c
> +++ b/drivers/nvme/host/rdma.c
> @@ -1767,6 +1767,21 @@ static void nvme_rdma_recv_done(struct ib_cq *cq, struct ib_wc *wc)
>   		return;
>   	}
>   
> +	/* received data length checking */
> +	if (unlikely(wc->byte_len < len)) {
> +		/* zero bytes message could be ignored */
> +		if (!wc->byte_len) {
> +			nvme_rdma_post_recv(queue, qe);
> +			return;
> +		}

Nothing in the spec defines zero-length messages, hence we cannot
support something that is not standard. If your array needs this,
please submit a TPAR to the NVMe TWG.