Re: [PATCH v6 4/9] sysfs: add sysfs_change_owner()

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Tue, Feb 25, 2020 at 02:19:33PM +0100, Christian Brauner wrote:
> Add a helper to change the owner of sysfs objects.
> This function will be used to correctly account for kobject ownership
> changes, e.g. when moving network devices between network namespaces.
> 
> This mirrors how a kobject is added through driver core which in its guts is
> done via kobject_add_internal() which in summary creates the main directory via
> create_dir(), populates that directory with the groups associated with the
> ktype of the kobject (if any) and populates the directory with the basic
> attributes associated with the ktype of the kobject (if any). These are the
> basic steps that are associated with adding a kobject in sysfs.
> Any additional properties are added by the specific subsystem itself (not by
> driver core) after it has registered the device. So for the example of network
> devices, a network device will e.g. register a queue subdirectory under the
> basic sysfs directory for the network device and than further subdirectories
> within that queues subdirectory.  But that is all specific to network devices
> and they call the corresponding sysfs functions to do that directly when they
> create those queue objects. So anything that a subsystem adds outside of what
> driver core does must also be changed by it (That's already true for removal of
> files it created outside of driver core.) and it's the same for ownership
> changes.
> 
> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

Thanks for the documentation update, looks good:

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>