Re: [PATCH RFC 2/2] libata: Use scsi cmnd budget token for qc tag for SAS host

Damien Le Moal
2022-03-16T23:23:20Z

On 3/16/22 19:46, John Garry wrote:
> On 16/03/2022 08:34, Christoph Hellwig wrote:
>> In addition to the comments from Damien: I think we should kill
>> ata_qc_new_init as well. It is a bit pointless and having it in
>> libata-core.c when it pokes into scsi internals also doesn't make sense.
>>
>> So maybe something like:
>
> Seems reasonable to me at least.

Yep, that will be a nice cleanup.

>
> But I'd send these as 2x separate patches.
>
>> * sata_async_notification - SATA async notification handler
>> * @ap: ATA port where async notification is received
>> diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
>> index ed8be585a98f7c..5e0bc7b05a107e 100644
>> --- a/drivers/ata/libata-scsi.c
>> +++ b/drivers/ata/libata-scsi.c
>> @@ -638,24 +638,44 @@ EXPORT_SYMBOL_GPL(ata_scsi_ioctl);
>> static struct ata_queued_cmd *ata_scsi_qc_new(struct ata_device *dev,
>> struct scsi_cmnd *cmd)
>> {
> ...
>
>>
>> - if (scsi_cmd_to_rq(cmd)->rq_flags & RQF_QUIET)
>> - qc->flags |= ATA_QCFLAG_QUIET;
>> + if (ap->flags & ATA_FLAG_SAS_HOST) {
>> + /* XXX: add a comment here why SAS is different */
>
> I think this is simply because SAS hosts have shost.can_queue > 32
>
>> + if (WARN_ON_ONCE(cmd->budget_token >= ATA_MAX_QUEUE))
>> + goto fail;
>> + tag = cmd->budget_token;
>
> thanks,
> John

--
Damien Le Moal
Western Digital Research