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

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

[Zijun Hu]

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);
 }
 EXPORT_SYMBOL_GPL(framer_provider_simple_of_xlate);

---
base-commit: 9f16d5e6f220661f73b36a4be1b21575651d8833
change-id: 20241124-framer-core-fix-6c1f04ed3c5d

Best regards,
-- 
Zijun Hu <quic_zijuhu@quicinc.com>

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

[Simon Horman]

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);

...

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

[Zijun Hu]

On 2024/12/13 00:41, Simon Horman wrote:
>>  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);
> 
thank you Simon for code review.
good suggestion. let me take it in v2.

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

Successful class_find_device_by_of_node() invocation will increase the
refcount of @target_dev, so i put_device() here to keep the same logic
as original.

thank you.