Re: [PATCH 2/3] scsi: libsas: Define NCQ Priority sysfs attributes for SATA devices

[John Garry <john.g.garry@oracle.com>]

On 01/03/2024 01:37, Igor Pylypiv wrote:
> Libata sysfs attributes cannot be used for libsas managed SATA devices
> because the ata_port location is different for libsas.
> 
> Defined sysfs attributes (visible for SATA devices only):
> - /sys/block/*/device/sas_ncq_prio_enable
> - /sys/block/*/device/sas_ncq_prio_supported

it would be good to show the full path

> 
> The newly defined attributes will pass the correct ata_port to libata
> helper functions.
> 
> Signed-off-by: Igor Pylypiv <ipylypiv@google.com>
> Reviewed-by: TJ Adams <tadamsjr@google.com>
> ---
>   drivers/scsi/libsas/sas_ata.c | 87 +++++++++++++++++++++++++++++++++++
>   include/scsi/sas_ata.h        |  6 +++
>   2 files changed, 93 insertions(+)
> 
> diff --git a/drivers/scsi/libsas/sas_ata.c b/drivers/scsi/libsas/sas_ata.c
> index 12e2653846e3..e0b19eee09b5 100644
> --- a/drivers/scsi/libsas/sas_ata.c
> +++ b/drivers/scsi/libsas/sas_ata.c
> @@ -964,3 +964,90 @@ int sas_execute_ata_cmd(struct domain_device *device, u8 *fis, int force_phy_id)
>   			       force_phy_id, &tmf_task);
>   }
>   EXPORT_SYMBOL_GPL(sas_execute_ata_cmd);
> +
> +static ssize_t sas_ncq_prio_supported_show(struct device *device,
> +					   struct device_attribute *attr,
> +					   char *buf)
> +{
> +	struct scsi_device *sdev = to_scsi_device(device);
> +	struct domain_device *ddev = sdev_to_domain_dev(sdev);
> +	int res;
> +
> +	// This attribute shall be visible for SATA devices only

Please don't use c99 comment style

> +	if (WARN_ON(!dev_is_sata(ddev)))
> +		return -EINVAL;
> +
> +	res = ata_ncq_prio_supported(ddev->sata_dev.ap, sdev);
> +	if (res < 0)
> +		return res;
> +
> +	return sysfs_emit(buf, "%u\n", res);
> +}
> +static DEVICE_ATTR_RO(sas_ncq_prio_supported);
> +
> +static ssize_t sas_ncq_prio_enable_show(struct device *device,
> +					struct device_attribute *attr,
> +					char *buf)
> +{
> +	struct scsi_device *sdev = to_scsi_device(device);
> +	struct domain_device *ddev = sdev_to_domain_dev(sdev);
> +	int res;
> +
> +	// This attribute shall be visible for SATA devices only
> +	if (WARN_ON(!dev_is_sata(ddev)))
> +		return -EINVAL;
> +
> +	res = ata_ncq_prio_enabled(ddev->sata_dev.ap, sdev);
> +	if (res < 0)
> +		return res;
> +
> +	return sysfs_emit(buf, "%u\n", res);
> +}
> +
> +static ssize_t sas_ncq_prio_enable_store(struct device *device,
> +					 struct device_attribute *attr,
> +					 const char *buf, size_t len)
> +{
> +	struct scsi_device *sdev = to_scsi_device(device);
> +	struct domain_device *ddev = sdev_to_domain_dev(sdev);
> +	long input;
> +	int res;
> +
> +	// This attribute shall be visible for SATA devices only
> +	if (WARN_ON(!dev_is_sata(ddev)))
> +		return -EINVAL;
> +
> +	res = kstrtol(buf, 10, &input);

I think that kstrtobool_from_user() could be used. But 
kstrtobool_from_user() handles more than 0/1, so that would be a 
different behaviour, so maybe better not to use.

I would also suggest factor out some of ata_ncq_prio_enable_store() with 
this, but a public API which accepts char * would be a bit odd.


> +	if (res)
> +		return res;
> +	if ((input < 0) || (input > 1))
> +		return -EINVAL;
> +
> +	return ata_ncq_prio_enable(ddev->sata_dev.ap, sdev, input) ? : len;

Please don't use ternary operator like this. This seems more 
straightforfward:

res = ata_ncq_prio_enable();
if (res)
	return res;
return len;

> +}
> +static DEVICE_ATTR_RW(sas_ncq_prio_enable);
> +
> +static struct attribute *sas_ata_sdev_attrs[] = {
> +	&dev_attr_sas_ncq_prio_supported.attr,
> +	&dev_attr_sas_ncq_prio_enable.attr,
> +	NULL
> +};
> +
> +static umode_t sas_ata_attr_is_visible(struct kobject *kobj,
> +				       struct attribute *attr, int i)
> +{
> +	struct device *dev = kobj_to_dev(kobj);
> +	struct scsi_device *sdev = to_scsi_device(dev);
> +	struct domain_device *ddev = sdev_to_domain_dev(sdev);
> +
> +	if (!dev_is_sata(ddev))
> +		return 0;
> +
> +	return attr->mode;
> +}
> +
> +const struct attribute_group sas_ata_sdev_attr_group = {
> +	.attrs = sas_ata_sdev_attrs,
> +	.is_visible = sas_ata_attr_is_visible,
> +};
> +EXPORT_SYMBOL_GPL(sas_ata_sdev_attr_group);
> diff --git a/include/scsi/sas_ata.h b/include/scsi/sas_ata.h
> index 2f8c719840a6..cded782fdf33 100644
> --- a/include/scsi/sas_ata.h
> +++ b/include/scsi/sas_ata.h
> @@ -39,6 +39,8 @@ int smp_ata_check_ready_type(struct ata_link *link);
>   int sas_discover_sata(struct domain_device *dev);
>   int sas_ata_add_dev(struct domain_device *parent, struct ex_phy *phy,
>   		    struct domain_device *child, int phy_id);
> +
> +extern const struct attribute_group sas_ata_sdev_attr_group;
>   #else
>   
>   static inline void sas_ata_disabled_notice(void)
> @@ -123,6 +125,10 @@ static inline int sas_ata_add_dev(struct domain_device *parent, struct ex_phy *p
>   	sas_ata_disabled_notice();
>   	return -ENODEV;
>   }
> +
> +static const struct attribute_group sas_ata_sdev_attr_group = {
> +	.attrs = NULL,
> +};
>   #endif
>   
>   #endif /* _SAS_ATA_H_ */