Re: [PATCH 31/31] pm8001: use block-layer tags for ccb allocation

[John Garry <john.garry@huawei.com>]

On 22/02/2021 13:24, Hannes Reinecke wrote:
> @ -4398,9 +4397,9 @@ static int pm8001_chip_reg_dev_req(struct pm8001_hba_info *pm8001_ha,
>   	circularQ = &pm8001_ha->inbnd_q_tbl[0];
>   
>   	memset(&payload, 0, sizeof(payload));
> -	rc = pm8001_tag_alloc(pm8001_ha, &tag);
> -	if (rc)
> -		return rc;
> +	tag = pm8001_tag_alloc(pm8001_ha, dev);
> +	if (tag == -1)
> +		return -SAS_QUEUE_FULL;
>   	ccb = &pm8001_ha->ccb_info[tag];
>   	ccb->device = pm8001_dev;
>   	ccb->ccb_tag = tag;
> @@ -4434,6 +4433,8 @@ static int pm8001_chip_reg_dev_req(struct pm8001_hba_info *pm8001_ha,
>   		SAS_ADDR_SIZE);
>   	rc = pm8001_mpi_build_cmd(pm8001_ha, circularQ, opc, &payload,
>   			sizeof(payload), 0);

So this above code means that we send on queue #0 always.

However, since we hope to use managed interrupt in the future, the 
interrupt for queue may be offline.

That's why I don't like storing a tag in sas_task structure. We already 
can get it elsewhere in the structure.

I would rather get it from sas_task.slow_task in this case, which saves 
the request/scsi_cmd pointer, and we can use blk_mq_unique_tag_to_hwq() 
here to get the tag and queue index.

Thanks,
John

> +	if (rc)
> +		pm8001_tag_free(pm8001_ha, tag);
>   	return rc;
>   }