[05/18] software_node: Alter software_node_unregister_nodes() to unregister the array in reverse order

Software nodes that are children of another software node should be
unregistered before their parent. To allow easy unregistering of an array
of software_nodes ordered parent to child, reverse the order in which
this function unregisters software_nodes.

Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Daniel Scally <djrscally@gmail.com>
---
Changes since RFC v3:

	Switched this functionality from a new function to replacing
	the existing software_nodes_unregister_nodes()

 drivers/base/swnode.c | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

Hi Daniel,

Thank you for the patch.

On Mon, Nov 30, 2020 at 01:31:16PM +0000, Daniel Scally wrote:
> Software nodes that are children of another software node should be
> unregistered before their parent. To allow easy unregistering of an array
> of software_nodes ordered parent to child, reverse the order in which
> this function unregisters software_nodes.
> 
> Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> Signed-off-by: Daniel Scally <djrscally@gmail.com>

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

> ---
> Changes since RFC v3:
> 
> 	Switched this functionality from a new function to replacing
> 	the existing software_nodes_unregister_nodes()
> 
>  drivers/base/swnode.c | 19 ++++++++++++-------
>  1 file changed, 12 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/base/swnode.c b/drivers/base/swnode.c
> index af7930b3679e..d39e1c76d98d 100644
> --- a/drivers/base/swnode.c
> +++ b/drivers/base/swnode.c
> @@ -720,20 +720,25 @@ EXPORT_SYMBOL_GPL(software_node_register_nodes);
>  
>  /**
>   * software_node_unregister_nodes - Unregister an array of software nodes
> - * @nodes: Zero terminated array of software nodes to be unregistered
> + * @nodes: Zero terminated array of software nodes to be unregistered. If
> + * parent pointers are set up in any of the software nodes then the array
> + * MUST be ordered such that parents come before their children.
>   *
>   * Unregister multiple software nodes at once.
>   *
> - * NOTE: Be careful using this call if the nodes had parent pointers set up in
> - * them before registering.  If so, it is wiser to remove the nodes
> - * individually, in the correct order (child before parent) instead of relying
> - * on the sequential order of the list of nodes in the array.
> + * NOTE: If you are uncertain whether the array is ordered such that
> + * parents will be unregistered before their children, it is wiser to
> + * remove the nodes individually, in the correct order (child before
> + * parent).
>   */
>  void software_node_unregister_nodes(const struct software_node *nodes)
>  {
> -	int i;
> +	unsigned int i = 0;
> +
> +	while (nodes[i].name)
> +		i++;
>  
> -	for (i = 0; nodes[i].name; i++)
> +	while (i--)
>  		software_node_unregister(&nodes[i]);
>  }
>  EXPORT_SYMBOL_GPL(software_node_unregister_nodes);

On Mon, Nov 30, 2020 at 01:31:16PM +0000, Daniel Scally wrote:
> Software nodes that are children of another software node should be
> unregistered before their parent. To allow easy unregistering of an array
> of software_nodes ordered parent to child, reverse the order in which
> this function unregisters software_nodes.

Should be folded in the previous patch. Otherwise we will have a history point
where register() behaves differently to unregister().

...

> + * @nodes: Zero terminated array of software nodes to be unregistered. If
> + * parent pointers are set up in any of the software nodes then the array
> + * MUST be ordered such that parents come before their children.

Please, leave field description short. Rather add another note to the
Description below.

>   *
>   * Unregister multiple software nodes at once.
>   *
> - * NOTE: Be careful using this call if the nodes had parent pointers set up in
> - * them before registering.  If so, it is wiser to remove the nodes
> - * individually, in the correct order (child before parent) instead of relying
> - * on the sequential order of the list of nodes in the array.
> + * NOTE: If you are uncertain whether the array is ordered such that
> + * parents will be unregistered before their children, it is wiser to
> + * remove the nodes individually, in the correct order (child before
> + * parent).
>   */

Hi Andy

On 30/11/2020 17:45, Andy Shevchenko wrote:
> On Mon, Nov 30, 2020 at 01:31:16PM +0000, Daniel Scally wrote:
>> Software nodes that are children of another software node should be
>> unregistered before their parent. To allow easy unregistering of an array
>> of software_nodes ordered parent to child, reverse the order in which
>> this function unregisters software_nodes.
> 
> Should be folded in the previous patch. Otherwise we will have a history point
> where register() behaves differently to unregister().

OK sure, I'll squash them - and thanks for your comments on the previous
patch, I condensed the conditionals as you suggest

> ...
> 
>> + * @nodes: Zero terminated array of software nodes to be unregistered. If
>> + * parent pointers are set up in any of the software nodes then the array
>> + * MUST be ordered such that parents come before their children.
> 
> Please, leave field description short. Rather add another note to the
> Description below.

Ack