linux-kernel - Re: [PATCH v2 5/5] ufs: core: Add error handling for MCQ mode

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Date:   Tue, 25 Apr 2023 17:21:44 -0700
From:   Bart Van Assche <bvanassche@....org>
To:     "Bao D. Nguyen" <quic_nguyenb@...cinc.com>,
        quic_asutoshd@...cinc.com, quic_cang@...cinc.com, mani@...nel.org,
        Powen.Kao@...iatek.com, stanley.chu@...iatek.com,
        adrian.hunter@...el.com, beanhuo@...ron.com, avri.altman@....com,
        martin.petersen@...cle.com
Cc:     linux-scsi@...r.kernel.org, Alim Akhtar <alim.akhtar@...sung.com>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 5/5] ufs: core: Add error handling for MCQ mode

On 4/17/23 14:05, Bao D. Nguyen wrote:
> +		/* MCQ mode */
> +		if (is_mcq_enabled(hba))
> +			return ufshcd_clear_cmds(hba, 1UL << lrbp->task_tag);

The above code will trigger an overflow if lrbp->task_tag >= 8 * 
sizeof(unsigned long). That's not acceptable.

>   static irqreturn_t ufshcd_transfer_req_compl(struct ufs_hba *hba)
>   {
> +	struct ufshcd_lrb *lrbp;
> +	u32 hwq_num, utag;
> +	int tag;
> +
>   	/* Resetting interrupt aggregation counters first and reading the
>   	 * DOOR_BELL afterward allows us to handle all the completed requests.
>   	 * In order to prevent other interrupts starvation the DB is read once
> @@ -5580,7 +5590,22 @@ static irqreturn_t ufshcd_transfer_req_compl(struct ufs_hba *hba)
>   	 * Ignore the ufshcd_poll() return value and return IRQ_HANDLED since we
>   	 * do not want polling to trigger spurious interrupt complaints.
>   	 */
> -	ufshcd_poll(hba->host, UFSHCD_POLL_FROM_INTERRUPT_CONTEXT);
> +	if (!is_mcq_enabled(hba)) {
> +		ufshcd_poll(hba->host, UFSHCD_POLL_FROM_INTERRUPT_CONTEXT);
> +		goto out;
> +	}
> +
> +	/* MCQ mode */
> +	for (tag = 0; tag < hba->nutrs; tag++) {
> +		lrbp = &hba->lrb[tag];
> +		if (lrbp->cmd) {
> +			utag = blk_mq_unique_tag(scsi_cmd_to_rq(lrbp->cmd));
> +			hwq_num = blk_mq_unique_tag_to_hwq(utag);
> +			ufshcd_poll(hba->host, hwq_num);
> +		}
> +	}

Is my understanding correct that ufshcd_transfer_req_compl() is only 
called from single doorbell code paths and hence that the above change 
is not necessary?


> +	if (is_mcq_enabled(hba)) {
> +		struct ufshcd_lrb *lrbp;
> +		int tag;
> +
> +		for (tag = 0; tag < hba->nutrs; tag++) {
> +			lrbp = &hba->lrb[tag];
> +			if (lrbp->cmd) {
> +				ret = ufshcd_try_to_abort_task(hba, tag);
> +				dev_err(hba->dev, "Aborting tag %d / CDB %#02x %s\n", tag,
> +					hba->lrb[tag].cmd ? hba->lrb[tag].cmd->cmnd[0] : -1,
> +					ret ? "failed" : "succeeded");
> +			}
> +			if (ret) {
> +				needs_reset = true;
> +				goto out;
> +			}
> +		}
> +	} else {
> +		/* Clear pending transfer requests */
> +		for_each_set_bit(tag, &hba->outstanding_reqs, hba->nutrs) {
> +			ret = ufshcd_try_to_abort_task(hba, tag);
> +			dev_err(hba->dev, "Aborting tag %d / CDB %#02x %s\n", tag,
> +				hba->lrb[tag].cmd ? hba->lrb[tag].cmd->cmnd[0] : -1,
> +				ret ? "failed" : "succeeded");
> +			if (ret) {
> +				needs_reset = true;
> +				goto out;
> +			}
>   		}
>   	}

Please introduce helper functions for the MCQ and SDB code paths such 
that the nesting level of the above code is reduced.

Thanks,

Bart.