linux-kernel - Re: [PATCH] hwmon: (dell-smm) Simplify with cleanup.h

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Message-ID: <f0944d58-c53c-4d31-98f3-dbe21d27d285@wanadoo.fr>
Date: Wed, 3 Jul 2024 20:03:15 +0200
From: Christophe JAILLET <christophe.jaillet@...adoo.fr>
To: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
 Pali Rohár <pali@...nel.org>,
 Jean Delvare <jdelvare@...e.com>, Guenter Roeck <linux@...ck-us.net>,
 linux-hwmon@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] hwmon: (dell-smm) Simplify with cleanup.h

Le 03/07/2024 à 10:31, Krzysztof Kozlowski a écrit :
> Allocate memory, which is being freed at end of the scope, to make the
> code a bit simpler.
> 
> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
> ---
>   drivers/hwmon/dell-smm-hwmon.c | 7 +++----
>   1 file changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/hwmon/dell-smm-hwmon.c b/drivers/hwmon/dell-smm-hwmon.c
> index 0362a13f6525..e72e26db6e10 100644
> --- a/drivers/hwmon/dell-smm-hwmon.c
> +++ b/drivers/hwmon/dell-smm-hwmon.c
> @@ -14,6 +14,7 @@
>   
>   #include <linux/acpi.h>
>   #include <linux/capability.h>
> +#include <linux/cleanup.h>
>   #include <linux/cpu.h>
>   #include <linux/ctype.h>
>   #include <linux/delay.h>
> @@ -1095,9 +1096,9 @@ static int dell_smm_init_cdev(struct device *dev, u8 fan_num)
>   	struct thermal_cooling_device *cdev;
>   	struct dell_smm_cooling_data *cdata;
>   	int ret = 0;
> -	char *name;
>   
> -	name = kasprintf(GFP_KERNEL, "dell-smm-fan%u", fan_num + 1);
> +	char *name __free(kfree) = kasprintf(GFP_KERNEL, "dell-smm-fan%u",
> +					     fan_num + 1);
>   	if (!name)
>   		return -ENOMEM;
>   
> @@ -1115,8 +1116,6 @@ static int dell_smm_init_cdev(struct device *dev, u8 fan_num)
>   		ret = -ENOMEM;
>   	}
>   
> -	kfree(name);
> -
>   	return ret;
>   }
>   

Hi,

going one step further, this could even be:

	cdata = devm_kmalloc(dev, sizeof(*cdata), GFP_KERNEL);
	if (!cdata)
		return -ENOMEM;

	cdata->fan_num = fan_num;
	cdata->data = data;
	cdev = devm_thermal_of_cooling_device_register(dev, NULL, name, cdata, 
&dell_smm_cooling_ops);
	if (IS_ERR(cdev)) {
		devm_kfree(dev, cdata);
		return PTR_ERR(cdev);
	}

	return 0;


This reduces indentation and is slightly more common when testing after 
devm_kmalloc()


Just my 2c,

CJ