linux-kernel - Re: [PATCH v2 1/2] scsi: increase scsi device's iodone_cnt in scsi

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Message-ID: <eabf6fff-93da-6d01-0abe-2f29602b0afb@oracle.com>
Date:   Tue, 22 Nov 2022 10:25:46 -0600
From:   Mike Christie <michael.christie@...cle.com>
To:     Wenchao Hao <haowenchao@...wei.com>,
        "James E . J . Bottomley" <jejb@...ux.ibm.com>,
        "Martin K . Petersen" <martin.petersen@...cle.com>,
        linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Steffen Maier <maier@...ux.ibm.com>, liuzhiqiang26@...wei.com,
        linfeilong@...wei.com
Subject: Re: [PATCH v2 1/2] scsi: increase scsi device's iodone_cnt in
 scsi_timeout()

On 10/21/22 6:56 PM, Wenchao Hao wrote:
> If an scsi command time out and going to be aborted, we should
> increase the iodone_cnt of the related scsi device, or the
> iodone_cnt would be less than iorequest_cnt
> 
> Increase iodone_cnt in scsi_timeout() would not cause double
> accounting issue, briefly analysed as following:
> 
>  - we add the iodone_cnt when BLK_EH_DONE would be returned in
>    scsi_timeout(), so the related scsi command's timeout event
>    would not happened
> 
>  - if the abort succeed and do not retry, the command would be done
>    with scsi_finish_command() which would not increase iodone_cnt;
> 
>  - if the abort succeed and retry the command, it would be requeue,
>    a scsi_dispatch_cmd() would be called and iorequest_cnt would be
>    increased again
> 
>  - if the abort failed, the error handler successfully recover the
>    device, do not retry this command, the command would be done
>    with scsi_finish_command() which would not increase iodone_cnt;
> 
>  - if the abort failed, the error handler successfully recover the
>    device, and retry this command, the iorequest_cnt would be
>    increased again
> 
> Signed-off-by: Wenchao Hao <haowenchao@...wei.com>
> ---
>  drivers/scsi/scsi_error.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
> index 6995c8979230..052b00f57b56 100644
> --- a/drivers/scsi/scsi_error.c
> +++ b/drivers/scsi/scsi_error.c
> @@ -356,6 +356,7 @@ enum blk_eh_timer_return scsi_timeout(struct request *req)
>  		 */
>  		if (test_and_set_bit(SCMD_STATE_COMPLETE, &scmd->state))
>  			return BLK_EH_RESET_TIMER;

You will need to rebase this patch because the above line is different now
so it doesn't apply.

It looks ok to me though.

Reviewed-by: Mike Christie <michael.christie@...cle.com>

> +		atomic_inc(&scmd->device->iodone_cnt);
>  		if (scsi_abort_command(scmd) != SUCCESS) {
>  			set_host_byte(scmd, DID_TIME_OUT);
>  			scsi_eh_scmd_add(scmd);