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Subject: Re: [PATCH v2] nvme-tcp: Do not reset transport on data digest errors
To:     Daniel Wagner <dwagner@suse.de>, linux-nvme@lists.infradead.org
Cc:     linux-kernel@vger.kernel.org, Sagi Grimberg <sagi@grimberg.me>,
        yi.he@emc.com
References: <20210825124259.28707-1-dwagner@suse.de>
From:   Hannes Reinecke <hare@suse.de>
Message-ID: <42916ab0-2997-b19f-47ee-e20e8e868a86@suse.de>
Date:   Wed, 25 Aug 2021 17:27:10 +0200
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On 8/25/21 2:42 PM, Daniel Wagner wrote:
> The spec says
> 
>    7.4.6.1 Digest Error handling
> 
>    When a host detects a data digest error in a C2HData PDU, that host
>    shall continue processing C2HData PDUs associated with the command and
>    when the command processing has completed, if a successful status was
>    returned by the controller, the host shall fail the command with a
>    non-fatal transport error.
> 
> Currently the transport is reseted when a data digest error is
> detected. To fix this, keep track of the final status in the queue
> object and use it when completing the request.
> 
> Signed-off-by: Daniel Wagner <dwagner@suse.de>
> ---
> 
> The status member placed so that it fills up a hole in struct
> nvme_tcp_request:
> 
> struct nvme_tcp_request {
>          struct nvme_request        req;                  /*     0    32 */
>          void *                     pdu;                  /*    32     8 */
>          struct nvme_tcp_queue *    queue;                /*    40     8 */
>          u32                        data_len;             /*    48     4 */
>          u32                        pdu_len;              /*    52     4 */
>          u32                        pdu_sent;             /*    56     4 */
>          u16                        ttag;                 /*    60     2 */
>          u16                        status;               /*    62     2 */
>          /* --- cacheline 1 boundary (64 bytes) --- */
>          struct list_head           entry;                /*    64    16 */
>          struct llist_node          lentry;               /*    80     8 */
>          __le32                     ddgst;                /*    88     4 */
> 
>          /* XXX 4 bytes hole, try to pack */
> 
>          struct bio *               curr_bio;             /*    96     8 */
>          struct iov_iter            iter;                 /*   104    40 */
>          /* --- cacheline 2 boundary (128 bytes) was 16 bytes ago --- */
>          size_t                     offset;               /*   144     8 */
>          size_t                     data_sent;            /*   152     8 */
>          enum nvme_tcp_send_state   state;                /*   160     4 */
> 
>          /* size: 168, cachelines: 3, members: 16 */
>          /* sum members: 160, holes: 1, sum holes: 4 */
>          /* padding: 4 */
>          /* last cacheline: 40 bytes */
> };
> 
> v1:
>   - https://lore.kernel.org/linux-nvme/20210805121541.77613-1-dwagner@suse.de/
>   - moved 'status' from nvme_tcp_queue to nvme_tcp_request.
> 
>   drivers/nvme/host/tcp.c | 25 +++++++++++++++++++++----
>   1 file changed, 21 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
> index 645025620154..23a8f7e11cfa 100644
> --- a/drivers/nvme/host/tcp.c
> +++ b/drivers/nvme/host/tcp.c
> @@ -45,6 +45,7 @@ struct nvme_tcp_request {
>   	u32			pdu_len;
>   	u32			pdu_sent;
>   	u16			ttag;
> +	u16			status;
>   	struct list_head	entry;
>   	struct llist_node	lentry;
>   	__le32			ddgst;
> @@ -485,7 +486,9 @@ static void nvme_tcp_error_recovery(struct nvme_ctrl *ctrl)
>   static int nvme_tcp_process_nvme_cqe(struct nvme_tcp_queue *queue,
>   		struct nvme_completion *cqe)
>   {
> +	struct nvme_tcp_request *req;
>   	struct request *rq;
> +	u16 status;
>   
>   	rq = nvme_find_rq(nvme_tcp_tagset(queue), cqe->command_id);
>   	if (!rq) {
> @@ -496,7 +499,12 @@ static int nvme_tcp_process_nvme_cqe(struct nvme_tcp_queue *queue,
>   		return -EINVAL;
>   	}
>   
> -	if (!nvme_try_complete_req(rq, cqe->status, cqe->result))
> +	req = blk_mq_rq_to_pdu(rq);
> +	status = req->status;
> +	if (status == NVME_SC_SUCCESS)
> +		status = cqe->status;
> +
> +	if (!nvme_try_complete_req(rq, status, cqe->result))
>   		nvme_complete_rq(rq);
>   	queue->nr_cqe++;
>   
> @@ -506,6 +514,7 @@ static int nvme_tcp_process_nvme_cqe(struct nvme_tcp_queue *queue,
>   static int nvme_tcp_handle_c2h_data(struct nvme_tcp_queue *queue,
>   		struct nvme_tcp_data_pdu *pdu)
>   {
> +	struct nvme_tcp_request *req;
>   	struct request *rq;
>   
>   	rq = nvme_find_rq(nvme_tcp_tagset(queue), pdu->command_id);
> @@ -534,6 +543,8 @@ static int nvme_tcp_handle_c2h_data(struct nvme_tcp_queue *queue,
>   		return -EPROTO;
>   	}
>   
> +	req = blk_mq_rq_to_pdu(rq);
> +	req->status = NVME_SC_SUCCESS;
>   	return 0;
>   }
>   

Can't you move the initialisation to nvme_tcp_setup_cmd_pdu()?
That'll save to to have to reference the tcp request here ...

> @@ -758,7 +769,7 @@ static int nvme_tcp_recv_data(struct nvme_tcp_queue *queue, struct sk_buff *skb,
>   			queue->ddgst_remaining = NVME_TCP_DIGEST_LENGTH;
>   		} else {
>   			if (pdu->hdr.flags & NVME_TCP_F_DATA_SUCCESS) {
> -				nvme_tcp_end_request(rq, NVME_SC_SUCCESS);
> +				nvme_tcp_end_request(rq, req->status);
>   				queue->nr_cqe++;
>   			}
>   			nvme_tcp_init_recv_ctx(queue);
> @@ -788,18 +799,24 @@ static int nvme_tcp_recv_ddgst(struct nvme_tcp_queue *queue,
>   		return 0;
>   
>   	if (queue->recv_ddgst != queue->exp_ddgst) {
> +		struct request *rq = nvme_cid_to_rq(nvme_tcp_tagset(queue),
> +					pdu->command_id);
> +		struct nvme_tcp_request *req = blk_mq_rq_to_pdu(rq);
> +
> +		req->status = NVME_SC_DATA_XFER_ERROR;
> +
>   		dev_err(queue->ctrl->ctrl.device,
>   			"data digest error: recv %#x expected %#x\n",
>   			le32_to_cpu(queue->recv_ddgst),
>   			le32_to_cpu(queue->exp_ddgst));
> -		return -EIO;
>   	}
>   
>   	if (pdu->hdr.flags & NVME_TCP_F_DATA_SUCCESS) {
>   		struct request *rq = nvme_cid_to_rq(nvme_tcp_tagset(queue),
>   					pdu->command_id);
> +		struct nvme_tcp_request *req = blk_mq_rq_to_pdu(rq);
>   
> -		nvme_tcp_end_request(rq, NVME_SC_SUCCESS);
> +		nvme_tcp_end_request(rq, req->status);
>   		queue->nr_cqe++;
>   	}
>   
> 
Otherwise:

Reviewed-by: Hannes Reinecke <hare@suse.de>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                Kernel Storage Architect
hare@suse.de                              +49 911 74053 688
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