Re: [PATCH v4 5/6] of: implement of_move_node helper

[Sascha Hauer <sha@pengutronix.de>]

On Mon, Jun 12, 2023 at 02:51:03PM +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@pengutronix.de>
> ---
>  drivers/of/base.c | 18 ++++++++++++++++++
>  include/of.h      |  1 +
>  2 files changed, 19 insertions(+)
> 
> diff --git a/drivers/of/base.c b/drivers/of/base.c
> index e3416b5b75a7..43a4a923d9c5 100644
> --- a/drivers/of/base.c
> +++ b/drivers/of/base.c
> @@ -2695,6 +2695,24 @@ void of_delete_node(struct device_node *node)
>  	free(node);
>  }
>  
> +void of_move_node(struct device_node *parent, struct device_node *node)
> +{
> +	if (!node)
> +		return;
> +
> +	list_del(&node->list);
> +	list_del(&node->parent_list);
> +
> +	free(node->full_name);
> +	node->full_name = basprintf("%s/%s", parent->full_name, node->name);
> +
> +	if (!node->parent)
> +		return;

Why is the old parent relevant here? Even when node didn't have a parent
before you should still add it to the children list of the new parent.

Also node->parent should be set to the new parent.

You seem to honour the case that node didn't have a parent previously.
Does the list_del(&node->parent_list) work in this case? I can't see any
INIT_LIST_HEAD(&node->parent_list) in the code, so I assume running a
list_del on it results in a NULL pointer dereference.

Sascha

> +
> +	list_add(&node->list, &parent->list);
> +	list_add_tail(&node->parent_list, &parent->children);
> +}
> +
>  /*
>   * of_find_node_by_chosen - Find a node given a chosen property pointing at it
>   * @propname:   the name of the property containing a path or alias
> diff --git a/include/of.h b/include/of.h
> index 0037bad6c4d7..686c1632c267 100644
> --- a/include/of.h
> +++ b/include/of.h
> @@ -187,6 +187,7 @@ extern struct device_node *of_create_node(struct device_node *root,
>  extern void of_merge_nodes(struct device_node *np, const struct device_node *other);
>  extern struct device_node *of_copy_node(struct device_node *parent,
>  				const struct device_node *other);
> +void of_move_node(struct device_node *parent, struct device_node *node);
>  extern struct device_node *of_dup(const struct device_node *root);
>  extern void of_delete_node(struct device_node *node);
>  
> -- 
> 2.39.2
> 
> 
> 

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