Re: [PATCH v2] ata: libata-scsi: Fix get identity data failed

[yangxingui <yangxingui@huawei.com>]

On 2023/5/5 16:17, Damien Le Moal wrote:
> On 2023/05/05 11:57, Xingui Yang wrote:
>> The function ata_get_identity() uses the helper ata_scsi_find_dev() to get
>> the ata_device structure of a scsi device. However, when the ata device is
>> managed by libsas, ata_scsi_find_dev() returns NULL, turning
>> ata_get_identity() into a nop and always returns -ENOMSG.
> 
> What do you do to hit the issue ? A while back for me it was the queue depth
> setting causing problems. As Garry mentioned, this led to patch 141f3d6256e5
> ("ata: libata-sata: Fix device queue depth control").
Attempt to return the correct value at ata_scsi_find_dev() instead of 
NULL, when the ata device is managed by libsas?
> 
>>
>> Fix this by checking whether ATA_FLAG_SAS_HOST is set for ap->flags in
>> ata_scsi_find_dev(), as the flag is only used in libsas. If
>> ATA_FLAG_SAS_HOST is set, use sas_to_ata_dev() to find associated ATA
>> device.
>>
>> Signed-off-by: Xingui Yang <yangxingui@huawei.com>
>> ---
>> Changes to v1
>> - Let ata_scsi_find_dev() return the correct value and don't keep replacing
>> calls to ata_scsi_find_dev().
>>
>>   drivers/ata/libata-scsi.c | 12 ++++++++++--
>>   drivers/ata/libata.h      |  2 +-
>>   2 files changed, 11 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
>> index 7bb12deab70c..aa580ea341fa 100644
>> --- 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>
>>   #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 ?
If we use sdev_to_domain_dev(), there will be a compilation warning. But 
we can replace with scsidev->sdev_target->hostdata.
> 
>> +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) {
>> +		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.
As above, we can replace with scsidev->sdev_target->hostdata.

Thanks,
Xingui
> 
>> +	}
>>   
>> +	dev = __ata_scsi_find_dev(ap, scsidev);
>>   	if (unlikely(!dev || !ata_dev_enabled(dev)))
>>   		return NULL;
>>   
>> diff --git a/drivers/ata/libata.h b/drivers/ata/libata.h
>> index 926d0d33cd29..6d66f46da064 100644
>> --- a/drivers/ata/libata.h
>> +++ b/drivers/ata/libata.h
>> @@ -109,7 +109,7 @@ static inline void ata_acpi_bind_dev(struct ata_device *dev) {}
>>   
>>   /* libata-scsi.c */
>>   extern struct ata_device *ata_scsi_find_dev(struct ata_port *ap,
>> -					    const struct scsi_device *scsidev);
>> +					    struct scsi_device *scsidev);
>>   extern int ata_scsi_add_hosts(struct ata_host *host,
>>   			      const struct scsi_host_template *sht);
>>   extern void ata_scsi_scan_host(struct ata_port *ap, int sync);
>