Re: [RESEND 1/1] watchdog: simplify devm_watchdog_register_device

[Guenter Roeck <linux@roeck-us.net>]

On 5/21/21 12:16 AM, Tian Tao wrote:
> Use devm_add_action_or_reset() instead of devres_alloc() and
> devres_add(), which works the same. This will simplify the
> code. There is no functional changes.
> 
> Signed-off-by: Tian Tao <tiantao6@hisilicon.com>
> Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>

There is a functional change: With this patch applied, the watchdog
is registered first, before allocating memory, and then unregistered
if allocating that memory failed. I do not like that change,
and I think the code should remain as-is.

Guenter

> ---
>   drivers/watchdog/watchdog_core.c | 21 ++++++---------------
>   1 file changed, 6 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/watchdog/watchdog_core.c b/drivers/watchdog/watchdog_core.c
> index 5df0a22..cea6080 100644
> --- a/drivers/watchdog/watchdog_core.c
> +++ b/drivers/watchdog/watchdog_core.c
> @@ -364,9 +364,9 @@ void watchdog_unregister_device(struct watchdog_device *wdd)
>   
>   EXPORT_SYMBOL_GPL(watchdog_unregister_device);
>   
> -static void devm_watchdog_unregister_device(struct device *dev, void *res)
> +static void devm_watchdog_unregister_device(void *wdd)
>   {
> -	watchdog_unregister_device(*(struct watchdog_device **)res);
> +	watchdog_unregister_device(wdd);
>   }
>   
>   /**
> @@ -381,23 +381,14 @@ static void devm_watchdog_unregister_device(struct device *dev, void *res)
>   int devm_watchdog_register_device(struct device *dev,
>   				struct watchdog_device *wdd)
>   {
> -	struct watchdog_device **rcwdd;
>   	int ret;
>   
> -	rcwdd = devres_alloc(devm_watchdog_unregister_device, sizeof(*rcwdd),
> -			     GFP_KERNEL);
> -	if (!rcwdd)
> -		return -ENOMEM;
> -
>   	ret = watchdog_register_device(wdd);
> -	if (!ret) {
> -		*rcwdd = wdd;
> -		devres_add(dev, rcwdd);
> -	} else {
> -		devres_free(rcwdd);
> -	}
> +	if (ret)
> +		return ret;
>   
> -	return ret;
> +	return devm_add_action_or_reset(dev, devm_watchdog_unregister_device,
> +					wdd);
>   }
>   EXPORT_SYMBOL_GPL(devm_watchdog_register_device);
>   
>