Re: [PATCH net-next] net: wan: framer: Simplify API framer_provider_simple_of_xlate() implementation

[Simon Horman <horms@kernel.org>]

On Wed, Dec 11, 2024 at 09:28:20PM +0800, Zijun Hu wrote:
> From: Zijun Hu <quic_zijuhu@quicinc.com>
> 
> Simplify framer_provider_simple_of_xlate() implementation by API
> class_find_device_by_of_node().
> 
> Also correct comments to mark its parameter @dev as unused instead of
> @args in passing.
> 
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Signed-off-by: Zijun Hu <quic_zijuhu@quicinc.com>
> ---
>  drivers/net/wan/framer/framer-core.c | 20 +++++++-------------
>  1 file changed, 7 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/net/wan/framer/framer-core.c b/drivers/net/wan/framer/framer-core.c
> index f547c22e26ac2b9986e48ed77143f12a0c8f62fb..7b369d9c41613314860753b7927b209e58f45a91 100644
> --- a/drivers/net/wan/framer/framer-core.c
> +++ b/drivers/net/wan/framer/framer-core.c
> @@ -732,8 +732,8 @@ EXPORT_SYMBOL_GPL(devm_framer_create);
>  
>  /**
>   * framer_provider_simple_of_xlate() - returns the framer instance from framer provider
> - * @dev: the framer provider device
> - * @args: of_phandle_args (not used here)
> + * @dev: the framer provider device (not used here)
> + * @args: of_phandle_args
>   *
>   * Intended to be used by framer provider for the common case where #framer-cells is
>   * 0. For other cases where #framer-cells is greater than '0', the framer provider
> @@ -743,20 +743,14 @@ EXPORT_SYMBOL_GPL(devm_framer_create);
>  struct framer *framer_provider_simple_of_xlate(struct device *dev,
>  					       const struct of_phandle_args *args)
>  {
> -	struct class_dev_iter iter;
> -	struct framer *framer;
> -
> -	class_dev_iter_init(&iter, &framer_class, NULL, NULL);
> -	while ((dev = class_dev_iter_next(&iter))) {
> -		framer = dev_to_framer(dev);
> -		if (args->np != framer->dev.of_node)
> -			continue;
> +	struct device *target_dev;
>  
> -		class_dev_iter_exit(&iter);
> -		return framer;
> +	target_dev = class_find_device_by_of_node(&framer_class, args->np);
> +	if (target_dev) {
> +		put_device(target_dev);
> +		return dev_to_framer(target_dev);
>  	}
>  
> -	class_dev_iter_exit(&iter);
>  	return ERR_PTR(-ENODEV);

Hi Zijun Hu,

FWIIW, I think it would be more idiomatic to have the non-error path in the
main flow of execution, something like this (completely untested!):

	target_dev = class_find_device_by_of_node(&framer_class, args->np);
	if (!target_dev)
		return ERR_PTR(-ENODEV);

	put_device(target_dev);
	return dev_to_framer(target_dev);

Also, is it safe to put_device(target_dev) before
passing target_dev to dev_to_framer() ?

>  }
>  EXPORT_SYMBOL_GPL(framer_provider_simple_of_xlate);

...