Re: [PATCH net-next 1/3] device property: Introduce fwnode_for_each_available_child_node_scoped()

[Sakari Ailus]

Hi Javier,

On Tue, Oct 08, 2024 at 06:10:27PM +0200, Javier Carrasco wrote:
> Introduce the scoped variant of the
> fwnode_for_each_available_child_node() to automatically decrement the
> child's refcount when it goes out of scope, removing the need for
> explicit calls to fwnode_handle_put().
> 
> Signed-off-by: Javier Carrasco <javier.carrasco.cruz@xxxxxxxxx>
> ---
>  include/linux/property.h | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/include/linux/property.h b/include/linux/property.h
> index 61fc20e5f81f..b37508ecf606 100644
> --- a/include/linux/property.h
> +++ b/include/linux/property.h
> @@ -168,6 +168,11 @@ struct fwnode_handle *fwnode_get_next_available_child_node(
>  	for (child = fwnode_get_next_available_child_node(fwnode, NULL); child;\
>  	     child = fwnode_get_next_available_child_node(fwnode, child))
>  
> +#define fwnode_for_each_available_child_node_scoped(fwnode, child)	       \
> +	for (struct fwnode_handle *child __free(fwnode_handle) =	       \
> +		fwnode_get_next_available_child_node(fwnode, NULL); child;     \
> +	     child = fwnode_get_next_available_child_node(fwnode, child))
> +

On OF, the implementation of the .get_next_child_node() fwnode op is:

static struct fwnode_handle *
of_fwnode_get_next_child_node(const struct fwnode_handle *fwnode,
                              struct fwnode_handle *child)
{
        return of_fwnode_handle(of_get_next_available_child(to_of_node(fwnode),
                                                            to_of_node(child)));
}

On ACPI we currently have .device_is_available() returning false but that
probably should be returning true instead (it's been virtually unused
previously).

That makes fwnode_get_next_available_child_node() and
fwnode_get_next_child_node() equivalent on both ACPI and OF. Presumably
creating unavailable nodes would be useless on swnode, too.

So my question is: what do we gain by adding all these fwnode_*available()
helpers?

>  struct fwnode_handle *device_get_next_child_node(const struct device *dev,
>  						 struct fwnode_handle *child);

-- 
Regards,

Sakari Ailus