linux-kernel - Re: [PATCH v1] scsi: ufs: core: changing the status to check inflight

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Date: Fri, 5 Apr 2024 11:41:35 -0700
From: Bart Van Assche <bvanassche@....org>
To: SEO HOYOUNG <hy50.seo@...sung.com>, linux-scsi@...r.kernel.org,
 linux-kernel@...r.kernel.org, alim.akhtar@...sung.com, avri.altman@....com,
 jejb@...ux.ibm.com, martin.petersen@...cle.com, beanhuo@...ron.com,
 kwangwon.min@...sung.com, kwmad.kim@...sung.com, sh425.lee@...sung.com,
 quic_nguyenb@...cinc.com, cpgs@...sung.com, h10.kim@...sung.com
Subject: Re: [PATCH v1] scsi: ufs: core: changing the status to check inflight

On 4/5/24 00:16, SEO HOYOUNG wrote:
> According to below the patch applied, lrbp->cmd do not will NULL
> after call release_scsi_cmd()
> So check the rq->state unconditionally even if it is completed normally
> in ufshcd_cmd_inflight()
> 
> If occurred abort status and tm_cmd timeout, will run err_handler
> for re-init UFS.
> Then err_handler will check pending request for clearing cmd.
> At that time, check if the state of rq is not MQ_RQ_IDLE.
> In other words, check if it is MQ_RQ_COMPLETE or MQ_RQ_IN_FLIGHT.
> If rq->state is MQ_RQ_COMPLETE, it is already completed in the block,
> so there is no need to process the queue.

The above description does not explain the motivation for this patch
very well. How about the following description?

"ufshcd_cmd_inflight() is used to check whether or not a command is
in progress. Make it skip commands that have already completed by
changing the !blk_mq_request_started(rq) check into blk_mq_rq_state(rq) 
!= MQ_RQ_IN_FLIGHT. We cannot rely on lrbp->cmd since lrbp->cmd is not
cleared when a command completes."

> diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
> index 21429eec1b82..3f47ea584cb1 100644
> --- a/drivers/ufs/core/ufshcd.c
> +++ b/drivers/ufs/core/ufshcd.c
> @@ -3088,7 +3088,7 @@ bool ufshcd_cmd_inflight(struct scsi_cmnd *cmd)
>   		return false;
>   
>   	rq = scsi_cmd_to_rq(cmd);
> -	if (!blk_mq_request_started(rq))
> +	if (blk_mq_rq_state(rq) != MQ_RQ_IN_FLIGHT)
>   		return false;
>   
>   	return true;

Please convert the two return statements into a single return statement,
e.g. as follows:

	return cmd &&
	    blk_mq_rq_state(scsi_cmd_to_rq(cmd)) == MQ_RQ_IN_FLIGHT;

Thanks,

Bart.