Re: [PATCH RFC v3 37/41] libsas: add tag to struct sas_task

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

>>> -
>>> +    task->tag = cmd->request->tag;
>>>        task->scatter = scsi_sglist(cmd);
>>>        task->num_scatter = scsi_sg_count(cmd);
>>>        task->total_xfer_len = scsi_bufflen(cmd);
>>> diff --git a/include/scsi/libsas.h b/include/scsi/libsas.h
>>> index c927228019c9..af864f68b5cc 100644
>>> --- a/include/scsi/libsas.h
>>> +++ b/include/scsi/libsas.h
>>> @@ -594,6 +594,8 @@ struct sas_task {
>>>        u32    total_xfer_len;
>>>        u8     data_dir:2;      /* Use PCI_DMA_... */
>>> +    u32    tag;
>>
>> unsigned, yet we assign it -1?
>>
> Yeah, that's how the block layer does internally, too.
> Maybe we should export SCSI_NO_TAG and use it here.
> 

I think it's better that the LLDD would not have to deal with "no tag" 
scenario (pm8001 driver has to handle it in this series). Rather libsas 
can handle that, and fail an allocation of a slow_task to the LLDD instead.

Thanks,
John