Re: [PATCH v4 2/2] ufs: mcq: poll OCS after sq cleanup for device management commands

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

On 11/1/26 9:52 PM, Kiwoong Kim wrote:
> +static enum utp_ocs ufshcd_mcq_read_ocs(struct ufs_hw_queue *hwq,
> +					struct ufshcd_lrb *lrbp)
> +{
> +	guard(spinlock_irqsave)(&hwq->cq_lock);
> +	return READ_ONCE(lrbp->utr_descriptor_ptr->header.ocs);
> +}

READ_ONCE() is sufficient. I don't think that the spinlock helps here. 
Additionally, if the spinlock operations are left out, the function
ufshcd_mcq_read_ocs() is no longer necessary and can be inlined in its
only caller.

> +	/*
> +	 * For device management commands, there is no order guaranteed between
> +	 * OCS update and CUS update, which is why we need to wait here. SCSI
> +	 * commands are excluded because the OCS in their UTRD is not updated
> +	 * from the CQE.
> +	 */
> +	if (!err && blk_mq_is_reserved_rq(rq)) {
> +		enum utp_ocs ocs;
> +
> +		err = read_poll_timeout(ufshcd_mcq_read_ocs, ocs,
> +					ocs != OCS_INVALID_COMMAND_STATUS, 20,
> +					MCQ_POLL_US, false, hwq, lrbp);
> +	}

An error message should be reported if the above loop times out.

Thanks,

Bart.