Re: [PATCH net-next 07/10] drivers/base/power: add dpm_sysfs_change_owner()

[Rafael J. Wysocki]

On Wed, Feb 12, 2020 at 11:43 AM Christian Brauner
<christian.brauner@xxxxxxxxxx> wrote:
>
> Add a helper to change the owner of a device's power entries. This
> needs to happen when the ownership of a device is changed, e.g. when
> moving network devices between network namespaces.
> The ownership of a device's power entries is determined based on the
> ownership of the corresponding kobject, i.e. only if the ownership of a
> kobject is changed will this function change the ownership of the
> corresponding sysfs entries.
> This function will be used to correctly account for ownership changes,
> e.g. when moving network devices between network namespaces.
>
> Signed-off-by: Christian Brauner <christian.brauner@xxxxxxxxxx>
> ---
>  drivers/base/core.c        |  4 ++++
>  drivers/base/power/power.h |  2 ++
>  drivers/base/power/sysfs.c | 37 +++++++++++++++++++++++++++++++++++++
>  3 files changed, 43 insertions(+)
>
> diff --git a/drivers/base/core.c b/drivers/base/core.c
> index 262217287a09..dfaf6d3614fa 100644
> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -3515,6 +3515,10 @@ int device_change_owner(struct device *dev)
>         if (error)
>                 goto out;
>
> +       error = dpm_sysfs_change_owner(dev);
> +       if (error)
> +               goto out;
> +
>  #ifdef CONFIG_BLOCK
>         if (sysfs_deprecated && dev->class == &block_class)
>                 goto out;
> diff --git a/drivers/base/power/power.h b/drivers/base/power/power.h
> index 444f5c169a0b..f68490d0811b 100644
> --- a/drivers/base/power/power.h
> +++ b/drivers/base/power/power.h
> @@ -74,6 +74,7 @@ extern int pm_qos_sysfs_add_flags(struct device *dev);
>  extern void pm_qos_sysfs_remove_flags(struct device *dev);
>  extern int pm_qos_sysfs_add_latency_tolerance(struct device *dev);
>  extern void pm_qos_sysfs_remove_latency_tolerance(struct device *dev);
> +extern int dpm_sysfs_change_owner(struct device *dev);
>
>  #else /* CONFIG_PM */
>
> @@ -88,6 +89,7 @@ static inline void pm_runtime_remove(struct device *dev) {}
>
>  static inline int dpm_sysfs_add(struct device *dev) { return 0; }
>  static inline void dpm_sysfs_remove(struct device *dev) {}
> +static inline int dpm_sysfs_change_owner(struct device *dev) { return 0; }
>
>  #endif
>
> diff --git a/drivers/base/power/sysfs.c b/drivers/base/power/sysfs.c
> index d7d82db2e4bc..ce1fd346e854 100644
> --- a/drivers/base/power/sysfs.c
> +++ b/drivers/base/power/sysfs.c
> @@ -684,6 +684,43 @@ int dpm_sysfs_add(struct device *dev)
>         return rc;
>  }
>
> +int dpm_sysfs_change_owner(struct device *dev)
> +{
> +       int rc;
> +
> +       if (device_pm_not_required(dev))
> +               return 0;
> +
> +       rc = sysfs_group_change_owner(&dev->kobj, &pm_attr_group);
> +       if (rc)
> +               return rc;
> +
> +       if (pm_runtime_callbacks_present(dev)) {
> +               rc = sysfs_group_change_owner(&dev->kobj,
> +                                             &pm_runtime_attr_group);
> +               if (rc)
> +                       return rc;
> +       }
> +       if (device_can_wakeup(dev)) {
> +               rc = sysfs_group_change_owner(&dev->kobj,
> +                                             &pm_wakeup_attr_group);
> +               if (rc)
> +                       return rc;
> +       }
> +       if (dev->power.set_latency_tolerance) {
> +               rc = sysfs_group_change_owner(&dev->kobj,
> +                               &pm_qos_latency_tolerance_attr_group);
> +               if (rc)
> +                       return rc;
> +       }
> +       if (dev->power.wakeup && dev->power.wakeup->dev) {

This is related to the device_can_wakeup(dev) condition above (i.e. it
will never be 'true' if that one is 'false').

LGTM apart from this.

> +               rc = device_change_owner(dev->power.wakeup->dev);
> +               if (rc)
> +                       return rc;
> +       }
> +       return 0;
> +}
> +
>  int wakeup_sysfs_add(struct device *dev)
>  {
>         return sysfs_merge_group(&dev->kobj, &pm_wakeup_attr_group);
> --
> 2.25.0
>