Re: [PATCH 1/3] ata: libata-scsi: Fix ata_msense_control_ata_feature()

[Damien Le Moal <dlemoal@kernel.org>]

On 4/18/25 08:50, Igor Pylypiv wrote:
> On Wed, Apr 16, 2025 at 05:42:36PM +0900, Damien Le Moal wrote:
>> For the ATA features subpage of the control mode page, the T10 SAT-6
>> specifications state that:
>>
>> For a MODE SENSE command, the SATL shall return the CDL_CTRL field value
>> that was last set by an application client.
>>
>> However, the function ata_msense_control_ata_feature() always sets the
>> CDL_CTRL field to the 0x02 value to indicate support for the CDL T2A and
>> T2B pages. This is thus incorrect and the value 0x02 must be reported
>> only after the user enables the CDL feature, which is indicated with the
>> ATA_DFLAG_CDL_ENABLED device flag. When this flag is not set, the
>> CDL_CTRL field of the ATA feature subpage of the control mode page must
>> report a value of 0x00.
>>
>> Fix ata_msense_control_ata_feature() to report the correct values for
>> the CDL_CTRL field, according to the enable/disable state of the device
>> CDL feature.
>>
>> Fixes: df60f9c64576 ("scsi: ata: libata: Add ATA feature control sub-page translation")
>> Cc: stable@vger.kernel.org
>> Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
> 
> Reviewed-by: Igor Pylypiv <ipylypiv@google.com>
> 
>> ---
>>  drivers/ata/libata-scsi.c | 5 +++--
>>  1 file changed, 3 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
>> index 2796c0da8257..e6c652b8a541 100644
>> --- a/drivers/ata/libata-scsi.c
>> +++ b/drivers/ata/libata-scsi.c
>> @@ -2453,8 +2453,9 @@ static unsigned int ata_msense_control_ata_feature(struct ata_device *dev,
>>  	 */
>>  	put_unaligned_be16(ATA_FEATURE_SUB_MPAGE_LEN - 4, &buf[2]);
>>  
>> -	if (dev->flags & ATA_DFLAG_CDL)
>> -		buf[4] = 0x02; /* Support T2A and T2B pages */
>> +	if ((dev->flags & ATA_DFLAG_CDL) &&
> 
> Do we need to check the ATA_DFLAG_CDL flag? If ATA_DFLAG_CDL_ENABLED is set
> then ATA_DFLAG_CDL must be set as well?

In fact, MODE SENSE accesses to the f2h subpage of the control page is already
checked in ata_scsiop_mode_sense() and failed if the device does not have CDL.
So the check here is indeed useless. I dropped it.

> 
> ata_mselect_control_ata_feature() only checks the ATA_DFLAG_CDL_ENABLED flag.

I added a patch to check ATA_DFLAG_CDL for this function as we were not failing
the mode select command for devices that do not support CDL.

> 
>> +	    (dev->flags & ATA_DFLAG_CDL_ENABLED))
>> +		buf[4] = 0x02; /* T2A and T2B pages enabled */
>>  	else
>>  		buf[4] = 0;
>>  
>> -- 
>> 2.49.0
>>
>>
> 
> Thanks,
> Igor


-- 
Damien Le Moal
Western Digital Research