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Message-ID: <50bd90dc-d66a-ba7a-4b05-b2455d97e1ee@kernel.org>
Date:   Sun, 7 May 2023 23:59:17 +0900
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Subject: Re: [PATCH v2] ata: libata-scsi: Fix get identity data failed
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To:     yangxingui <yangxingui@huawei.com>,
        John Garry <john.g.garry@oracle.com>, jejb@linux.ibm.com,
        martin.petersen@oracle.com
Cc:     linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org,
        linuxarm@huawei.com, prime.zeng@hisilicon.com,
        kangfenglong@huawei.com
References: <20230505025712.19438-1-yangxingui@huawei.com>
 <291f1d97-9195-45ac-8e12-058f5c797277@kernel.org>
 <b13c9445-39c5-f207-d5d0-d6c86eee54ae@oracle.com>
 <1b703656-e966-63f8-19dd-33e4e9914676@huawei.com>
From:   Damien Le Moal <dlemoal@kernel.org>
Organization: Western Digital Research
In-Reply-To: <1b703656-e966-63f8-19dd-33e4e9914676@huawei.com>
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On 2023/05/05 18:14, yangxingui wrote:
> 
> 
> On 2023/5/5 16:25, John Garry wrote:
>> On 05/05/2023 09:17, Damien Le Moal wrote:
>>>> --- a/drivers/ata/libata-scsi.c
>>>> +++ b/drivers/ata/libata-scsi.c
>>>> @@ -26,6 +26,7 @@
>>>>   #include <scsi/scsi_device.h>
>>>>   #include <scsi/scsi_tcq.h>
>>>>   #include <scsi/scsi_transport.h>
>>>> +#include <scsi/libsas.h>
>>
>> hmmm... is it really acceptable that libata is referencing libsas? I 
>> didn't think that it would be. libsas uses libata, not the other way 
>> around.
> Yeah, I didn't expect that either. Is there any other way? If so, is 
> patch v1 OK?
>>
>>>>   #include <linux/libata.h>
>>>>   #include <linux/hdreg.h>
>>>>   #include <linux/uaccess.h>
>>>> @@ -2745,10 +2746,17 @@ static struct ata_device 
>>>> *__ata_scsi_find_dev(struct ata_port *ap,
>>>>    *    Associated ATA device, or %NULL if not found.
>>>>    */
>>>>   struct ata_device *
>>>> -ata_scsi_find_dev(struct ata_port *ap, const struct scsi_device 
>>>> *scsidev)
>>> Why drop the const ?
>>>
>>>> +ata_scsi_find_dev(struct ata_port *ap, struct scsi_device *scsidev)
>>>>   {
>>>> -    struct ata_device *dev = __ata_scsi_find_dev(ap, scsidev);
>>>> +    struct ata_device *dev;
>>>> +
>>>> +    if (ap->flags & ATA_FLAG_SAS_HOST) {
>>
>> And this is SAS host. Not necessarily libsas (even though with ipr 
>> libata usage gone, it would be the only user).
> Add a new flag only for libsas?

ATA_FLAG_SAS_HOST is now only used by libsas. So we should rename this flag to
ATA_FLAG_LIBSAS_HOST to be clear about it. And looking at how the flag is used
(in only 2 places), I wonder if we could get rid of it entirely...

With the ipr driver gone, there is a lot of cleanup in libata that can be done,
especially around EH code. Will be working on that.

> 
> Thanks,
> Xingui
> .
>>
>>>> +        struct domain_device *ddev = sdev_to_domain_dev(scsidev);
>>>> +
>>>> +        return sas_to_ata_dev(ddev);
>>> Do you really need the ddev variable ? Also, this really should be a 
>>> libsas
>>> helper. I beleive this pattern is repeated in several places in 
>>> libsas, so that
>>> would nicely clean things up.
>>>
>> Thanks,
>> John
>> .

-- 
Damien Le Moal
Western Digital Research