Re: [PATCH 1/2] software node: implement software_node_unregister()

[Heikki Krogerus]

On Sun, May 24, 2020 at 05:30:40PM +0200, Greg Kroah-Hartman wrote:
> Sometimes it is better to unregister individual nodes instead of trying
> to do them all at once with software_node_unregister_nodes(), so create
> software_node_unregister() so that you can unregister them one at a
> time.
> 
> This is especially important when creating nodes in a hierarchy, with
> parent -> children representations.  Children always need to be removed
> before a parent is, as the swnode logic assumes this is going to be the
> case.
> 
> Fix up the lib/test_printf.c fwnode_pointer() test which to use this new
> function as it had the problem of tearing things down in the backwards
> order.
> 
> Fixes: f1ce39df508d ("lib/test_printf: Add tests for %pfw printk modifier")
> Reported-by: Naresh Kamboju <naresh.kamboju@xxxxxxxxxx>
> Reported-by: kernel test robot <rong.a.chen@xxxxxxxxx>
> Cc: stable <stable@xxxxxxxxxxxxxxx>
> Cc: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> Cc: Brendan Higgins <brendanhiggins@xxxxxxxxxx>
> Cc: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
> Cc: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
> Cc: Petr Mladek <pmladek@xxxxxxxx>
> Cc: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> Cc: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
> Cc: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>
> Cc: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
> Cc: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

FWIW:

Reviewed-by: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>

> ---
>  drivers/base/swnode.c    | 27 +++++++++++++++++++++------
>  include/linux/property.h |  1 +
>  lib/test_printf.c        |  4 +++-
>  3 files changed, 25 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/base/swnode.c b/drivers/base/swnode.c
> index de8d3543e8fe..770b1f47a625 100644
> --- a/drivers/base/swnode.c
> +++ b/drivers/base/swnode.c
> @@ -712,17 +712,18 @@ EXPORT_SYMBOL_GPL(software_node_register_nodes);
>   * @nodes: Zero terminated array of software nodes to be unregistered
>   *
>   * 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.
>   */
>  void software_node_unregister_nodes(const struct software_node *nodes)
>  {
> -	struct swnode *swnode;
>  	int i;
>  
> -	for (i = 0; nodes[i].name; i++) {
> -		swnode = software_node_to_swnode(&nodes[i]);
> -		if (swnode)
> -			fwnode_remove_software_node(&swnode->fwnode);
> -	}
> +	for (i = 0; nodes[i].name; i++)
> +		software_node_unregister(&nodes[i]);
>  }
>  EXPORT_SYMBOL_GPL(software_node_unregister_nodes);
>  
> @@ -741,6 +742,20 @@ int software_node_register(const struct software_node *node)
>  }
>  EXPORT_SYMBOL_GPL(software_node_register);
>  
> +/**
> + * software_node_unregister - Unregister static software node
> + * @node: The software node to be unregistered
> + */
> +void software_node_unregister(const struct software_node *node)
> +{
> +	struct swnode *swnode;
> +
> +	swnode = software_node_to_swnode(node);
> +	if (swnode)
> +		fwnode_remove_software_node(&swnode->fwnode);
> +}
> +EXPORT_SYMBOL_GPL(software_node_unregister);
> +
>  struct fwnode_handle *
>  fwnode_create_software_node(const struct property_entry *properties,
>  			    const struct fwnode_handle *parent)
> diff --git a/include/linux/property.h b/include/linux/property.h
> index d86de017c689..0d4099b4ce1f 100644
> --- a/include/linux/property.h
> +++ b/include/linux/property.h
> @@ -441,6 +441,7 @@ int software_node_register_nodes(const struct software_node *nodes);
>  void software_node_unregister_nodes(const struct software_node *nodes);
>  
>  int software_node_register(const struct software_node *node);
> +void software_node_unregister(const struct software_node *node);
>  
>  int software_node_notify(struct device *dev, unsigned long action);
>  
> diff --git a/lib/test_printf.c b/lib/test_printf.c
> index 6b1622f4d7c2..fc63b8959d42 100644
> --- a/lib/test_printf.c
> +++ b/lib/test_printf.c
> @@ -637,7 +637,9 @@ static void __init fwnode_pointer(void)
>  	test(second_name, "%pfwP", software_node_fwnode(&softnodes[1]));
>  	test(third_name, "%pfwP", software_node_fwnode(&softnodes[2]));
>  
> -	software_node_unregister_nodes(softnodes);
> +	software_node_unregister(&softnodes[2]);
> +	software_node_unregister(&softnodes[1]);
> +	software_node_unregister(&softnodes[0]);
>  }
>  
>  static void __init
> -- 
> 2.26.2

thanks,

-- 
heikki