Re: [PATCH v2 2/2] ufs: core: requeue MCQ abort request

[Bart Van Assche <bvanassche@acm.org>]

On 9/1/24 7:18 PM, peter.wang@mediatek.com wrote:
> diff --git a/drivers/ufs/core/ufs-mcq.c b/drivers/ufs/core/ufs-mcq.c
> index afd9541f4bd8..abdc55a8b960 100644
> --- a/drivers/ufs/core/ufs-mcq.c
> +++ b/drivers/ufs/core/ufs-mcq.c
> @@ -642,6 +642,7 @@ static bool ufshcd_mcq_sqe_search(struct ufs_hba *hba,
>   		match = le64_to_cpu(utrd->command_desc_base_addr) & CQE_UCD_BA;
>   		if (addr == match) {
>   			ufshcd_mcq_nullify_sqe(utrd);
> +			lrbp->host_initiate_abort = true;
>   			ret = true;
>   			goto out;
>   		}

I think this is wrong. The above code is only executed if the SCSI core
decides to abort a SCSI command. It is up to the SCSI core to decide
whether or not to retry an aborted command.

> -	/* Release cmd in MCQ mode if abort succeeds */
> -	if (hba->mcq_enabled && (*ret == 0)) {
> -		hwq = ufshcd_mcq_req_to_hwq(hba, scsi_cmd_to_rq(lrbp->cmd));
> -		if (!hwq)
> -			return 0;
> -		spin_lock_irqsave(&hwq->cq_lock, flags);
> -		if (ufshcd_cmd_inflight(lrbp->cmd))
> -			ufshcd_release_scsi_cmd(hba, lrbp);
> -		spin_unlock_irqrestore(&hwq->cq_lock, flags);
> -	}
> +	/* Host will post to CQ with OCS_ABORTED after SQ cleanup */
> +	if (hba->mcq_enabled && (*ret == 0))
> +		lrbp->host_initiate_abort = true;

I think this code is racy because the UFS host controller may have 
posted a completion before the "lrbp->host_initiate_abort = true"
assignment is executed.

> + * @host_initiate_abort: Abort flag initiated by host

What is "Abort flag"? Please consider renaming "host_initiate_abort"
into "abort_initiated_by_err_handler" since I think that aborted
commands should only be retried if these have been aborted by
ufshcd_err_handler().

Thanks,

Bart.