[PATCH master v2 1/2] of: implement of_reparent_node helper

[Sascha Hauer]

On Thu, Jun 29, 2023 at 08:56:12AM +0200, Ahmad Fatoum wrote:
> Reparenting nodes can be a useful thing to do in fixups. Add a helper
> for that.
> 
> Signed-off-by: Ahmad Fatoum <a.fatoum at pengutronix.de>
> ---
> v1 -> v2:
>   - rename from of_move_node to of_reparent_node
>   - ensure that there's a parent to avoid null pointer deref
>     (Sascha)
>   - set node->parent to new_parent (Sascha)
>   - Remove broken condition on old parent (Sascha)
> ---
>  drivers/of/base.c           | 26 ++++++++++++++++++++++++++
>  include/of.h                |  1 +
>  test/self/of_manipulation.c |  8 ++++++--
>  3 files changed, 33 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/of/base.c b/drivers/of/base.c
> index 4dc1c76b136d..e1134e9c694b 100644
> --- a/drivers/of/base.c
> +++ b/drivers/of/base.c
> @@ -2697,6 +2697,32 @@ void of_delete_node(struct device_node *node)
>  	free(node);
>  }
>  
> +/*
> + * of_reparent_node - Move node from beneath one parent to another
> + * @new_parent: The new parent node
> + * @node        The node to be moved
> + */
> +int of_reparent_node(struct device_node *new_parent, struct device_node *node)
> +{
> +	if (!node)
> +		return 0;
> +
> +	if (!new_parent || !node->parent)
> +		return -EINVAL;
> +
> +	list_del(&node->parent_list);
> +	list_del(&node->list);

You could put these list operations into a if (node->parent), then @node
wouldn't necessarily need a parent.

> +
> +	free(node->full_name);
> +	node->full_name = basprintf("%s/%s", new_parent->full_name, node->name);

That fixes full_name of @node, but not its children.

One obvious solution would be to iterate over the children and fix the
name recursively. Another one would be to git rid of the full_name
member and generate the name dynamically when needed, but that wouldn't be
master material anymore.

Sascha

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