Re: [PATCH v3 01/31] scsi: libsas: Fix sas_ata_qc_issue() handling of NCQ NON DATA commands

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

On 14/02/2022 02:17, Damien Le Moal wrote:
> To detect for the DMA_NONE (no data transfer) DMA direction,
> sas_ata_qc_issue() tests if the command protocol is ATA_PROT_NODATA.
> This test does not include the ATA_CMD_NCQ_NON_DATA command as this
> command protocol is defined as ATA_PROT_NCQ_NODATA (equal to
> ATA_PROT_FLAG_NCQ) and not as ATA_PROT_NODATA.
> 
> To include both NCQ and non-NCQ commands when testing for the DMA_NONE
> DMA direction, use "!ata_is_data()".
> 
> Fixes: 176ddd89171d ("scsi: libsas: Reset num_scatter if libata marks qc as NODATA")
> Cc: stable@vger.kernel.org
> Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>

Regardless of comment below:
Reviewed-by: John Garry <john.garry@huawei.com>

> ---
>   drivers/scsi/libsas/sas_ata.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/scsi/libsas/sas_ata.c b/drivers/scsi/libsas/sas_ata.c
> index e0030a093994..50f779088b6e 100644
> --- a/drivers/scsi/libsas/sas_ata.c
> +++ b/drivers/scsi/libsas/sas_ata.c
> @@ -197,7 +197,7 @@ static unsigned int sas_ata_qc_issue(struct ata_queued_cmd *qc)
>   		task->total_xfer_len = qc->nbytes;
>   		task->num_scatter = qc->n_elem;
>   		task->data_dir = qc->dma_dir;
> -	} else if (qc->tf.protocol == ATA_PROT_NODATA) {
> +	} else if (!ata_is_data(qc->tf.protocol)) {

I was thinking ata_is_dma() would be more appropiate, but I suppose we 
don't have to use DMA.

>   		task->data_dir = DMA_NONE; >   	} else {
>   		for_each_sg(qc->sg, sg, qc->n_elem, si)