On 9/26/22 20:31, John Garry wrote:
> On 26/09/2022 00:08, Damien Le Moal wrote:
>> The function __ata_change_queue_depth() uses the helper
>> ata_scsi_find_dev() to get the ata_device structure of a scsi device and
>> set that device maximum queue depth. However, when the ata device is
>> managed by libsas,
>
> Yeah, this current code is utterly broken. Just a nit is that it would
> be good to mention that the sdev id is assigned by scsi_transport_sas
> (and not libata) for when using libsas.
>
> In my series "Allocate SCSI device earlier for ata port probe" I
> mentioned this problem of different id assignment scheme. It would be
> nice to try to commonize this.
>
>> ata_scsi_find_dev() returns NULL, turning
>> __ata_change_queue_depth() into a nop, which prevents the user from
>> setting the maximum queue depth of ATA devices used with libsas based
>> HBAs.
>>
>> Fix this by renaming __ata_change_queue_depth() to
>> ata_change_queue_depth() and adding a pointer to the ata_device
>> structure of the target device as argument. This pointer is provided by
>> ata_scsi_change_queue_depth() using ata_scsi_find_dev() in the case of
>> a libata managed device and by sas_change_queue_depth() using
>> sas_to_ata_dev() in the case of a libsas managed ata device.
>
> This seems ok. But could you alternatively use ata_for_each_dev() and
> match by ata_device.sdev pointer? That pointer is set quite late in the
> probe, though, so maybe it would not work.
Not sure I understand why we should search for the ata device again using
ata_for_each_dev() when sas_to_ata_dev() gives us directly what we need
for the libsas controlled device... Can you clarify ?
>
> As an aside, one other thing I noticed is that ata_device.private_data
> is unused. Maybe we should delete it - apparently it was added just for
> symmetry of libata structures.
>
> Thanks,
> John
>
>>
>> Signed-off-by: Damien Le Moal <damien.lemoal@xxxxxxxxxxxxxxxxxx>
>> ---
>> drivers/ata/libata-sata.c | 24 ++++++++++++------------
>> drivers/scsi/libsas/sas_scsi_host.c | 3 ++-
>> include/linux/libata.h | 4 ++--
>> 3 files changed, 16 insertions(+), 15 deletions(-)
>>
>> diff --git a/drivers/ata/libata-sata.c b/drivers/ata/libata-sata.c
>> index 7a5fe41aa5ae..13b9d0fdd42c 100644
>> --- a/drivers/ata/libata-sata.c
>> +++ b/drivers/ata/libata-sata.c
>> @@ -1018,26 +1018,25 @@ DEVICE_ATTR(sw_activity, S_IWUSR | S_IRUGO, ata_scsi_activity_show,
>> EXPORT_SYMBOL_GPL(dev_attr_sw_activity);
>>
>> /**
>> - * __ata_change_queue_depth - helper for ata_scsi_change_queue_depth
>> - * @ap: ATA port to which the device change the queue depth
>> + * ata_change_queue_depth - Set a device maximum queue depth
>> + * @ap: ATA port of the target device
>> + * @dev: target ATA device
>> * @sdev: SCSI device to configure queue depth for
>> * @queue_depth: new queue depth
>> *
>> - * libsas and libata have different approaches for associating a sdev to
>> - * its ata_port.
>> + * Helper to set a device maximum queue depth, usable with both libsas
>> + * and libata.
>> *
>> */
>> -int __ata_change_queue_depth(struct ata_port *ap, struct scsi_device *sdev,
>> - int queue_depth)
>> +int ata_change_queue_depth(struct ata_port *ap, struct ata_device *dev,
>> + struct scsi_device *sdev, int queue_depth)
>> {
>> - struct ata_device *dev;
>> unsigned long flags;
>>
>> - if (queue_depth < 1 || queue_depth == sdev->queue_depth)
>> + if (!dev || !ata_dev_enabled(dev))
>> return sdev->queue_depth;
>>
>> - dev = ata_scsi_find_dev(ap, sdev);
>> - if (!dev || !ata_dev_enabled(dev))
>> + if (queue_depth < 1 || queue_depth == sdev->queue_depth)
>> return sdev->queue_depth;
>>
>> /* NCQ enabled? */
>> @@ -1059,7 +1058,7 @@ int __ata_change_queue_depth(struct ata_port *ap, struct scsi_device *sdev,
>>
>> return scsi_change_queue_depth(sdev, queue_depth);
>> }
>> -EXPORT_SYMBOL_GPL(__ata_change_queue_depth);
>> +EXPORT_SYMBOL_GPL(ata_change_queue_depth);
>>
>> /**
>> * ata_scsi_change_queue_depth - SCSI callback for queue depth config
>> @@ -1080,7 +1079,8 @@ int ata_scsi_change_queue_depth(struct scsi_device *sdev, int queue_depth)
>> {
>> struct ata_port *ap = ata_shost_to_port(sdev->host);
>>
>> - return __ata_change_queue_depth(ap, sdev, queue_depth);
>> + return ata_change_queue_depth(ap, ata_scsi_find_dev(ap, sdev),
>> + sdev, queue_depth);
>> }
>> EXPORT_SYMBOL_GPL(ata_scsi_change_queue_depth);
>>
>> diff --git a/drivers/scsi/libsas/sas_scsi_host.c b/drivers/scsi/libsas/sas_scsi_host.c
>> index 9c82e5dc4fcc..a36fa1c128a8 100644
>> --- a/drivers/scsi/libsas/sas_scsi_host.c
>> +++ b/drivers/scsi/libsas/sas_scsi_host.c
>> @@ -872,7 +872,8 @@ int sas_change_queue_depth(struct scsi_device *sdev, int depth)
>> struct domain_device *dev = sdev_to_domain_dev(sdev);
>>
>> if (dev_is_sata(dev))
>> - return __ata_change_queue_depth(dev->sata_dev.ap, sdev, depth);
>> + return ata_change_queue_depth(dev->sata_dev.ap,
>> + sas_to_ata_dev(dev), sdev, depth);
>>
>> if (!sdev->tagged_supported)
>> depth = 1;
>> diff --git a/include/linux/libata.h b/include/linux/libata.h
>> index 698032e5ef2d..20765d1c5f80 100644
>> --- a/include/linux/libata.h
>> +++ b/include/linux/libata.h
>> @@ -1136,8 +1136,8 @@ extern int ata_scsi_slave_config(struct scsi_device *sdev);
>> extern void ata_scsi_slave_destroy(struct scsi_device *sdev);
>> extern int ata_scsi_change_queue_depth(struct scsi_device *sdev,
>> int queue_depth);
>> -extern int __ata_change_queue_depth(struct ata_port *ap, struct scsi_device *sdev,
>> - int queue_depth);
>> +extern int ata_change_queue_depth(struct ata_port *ap, struct ata_device *dev,
>> + struct scsi_device *sdev, int queue_depth);
>> extern struct ata_device *ata_dev_pair(struct ata_device *adev);
>> extern int ata_do_set_mode(struct ata_link *link, struct ata_device **r_failed_dev);
>> extern void ata_scsi_port_error_handler(struct Scsi_Host *host, struct ata_port *ap);
>
--
Damien Le Moal
Western Digital Research
