Re: [PATCH v6 2/7] scsi: libsas: Define NCQ Priority sysfs attributes for SATA devices

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

On 3/6/24 08:58, 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/sda/device/ncq_prio_enable
> - /sys/block/sda/device/ncq_prio_supported
> 
> The newly defined attributes will pass the correct ata_port to libata
> helper functions.
> 
> Reviewed-by: John Garry <john.g.garry@oracle.com>
> Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
> Reviewed-by: Jason Yan <yanaijie@huawei.com>
> Signed-off-by: Igor Pylypiv <ipylypiv@google.com>
> ---
>  drivers/scsi/libsas/sas_ata.c | 94 +++++++++++++++++++++++++++++++++++
>  include/scsi/sas_ata.h        |  6 +++
>  2 files changed, 100 insertions(+)
> 
> diff --git a/drivers/scsi/libsas/sas_ata.c b/drivers/scsi/libsas/sas_ata.c
> index 12e2653846e3..04b0bd9a4e01 100644
> --- a/drivers/scsi/libsas/sas_ata.c
> +++ b/drivers/scsi/libsas/sas_ata.c
> @@ -964,3 +964,97 @@ 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);
> +	bool supported;
> +	int rc;
> +
> +	/* This attribute shall be visible for SATA devices only */
> +	if (WARN_ON_ONCE(!dev_is_sata(ddev)))
> +		return -EINVAL;
> +
> +	rc = ata_ncq_prio_supported(ddev->sata_dev.ap, sdev, &supported);
> +	if (rc)
> +		return rc;
> +
> +	return sysfs_emit(buf, "%d\n", supported);
> +}
> +
> +DEVICE_ATTR(ncq_prio_supported, S_IRUGO, sas_ncq_prio_supported_show, NULL);
> +
> +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);
> +	bool enabled;
> +	int rc;
> +
> +	/* This attribute shall be visible for SATA devices only */
> +	if (WARN_ON_ONCE(!dev_is_sata(ddev)))
> +		return -EINVAL;
> +
> +	rc = ata_ncq_prio_enabled(ddev->sata_dev.ap, sdev, &enabled);
> +	if (rc)
> +		return rc;
> +
> +	return sysfs_emit(buf, "%d\n", enabled);
> +}
> +
> +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);
> +	bool enable;
> +	int rc;
> +
> +	/* This attribute shall be visible for SATA devices only */
> +	if (WARN_ON_ONCE(!dev_is_sata(ddev)))
> +		return -EINVAL;
> +
> +	rc = kstrtobool(buf, &enable);
> +	if (rc)
> +		return rc;
> +
> +	rc = ata_ncq_prio_enable(ddev->sata_dev.ap, sdev, enable);
> +	if (rc)
> +		return rc;
> +
> +	return len;
> +}
> +
> +DEVICE_ATTR(ncq_prio_enable, S_IRUGO | S_IWUSR,
> +	    sas_ncq_prio_enable_show, sas_ncq_prio_enable_store);
> +
> +static struct attribute *sas_ata_sdev_attrs[] = {
> +	&dev_attr_ncq_prio_supported.attr,
> +	&dev_attr_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..59a75cd8b5e0 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 __maybe_unused = {
> +	.attrs = NULL,
> +};

Looks OK, but I must say that I would prefer John's idea with the #define as
that removes the variable definition entirely.

>  #endif
>  
>  #endif /* _SAS_ATA_H_ */

-- 
Damien Le Moal
Western Digital Research