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Message-ID: <8cc11dd5-f599-cdf0-da05-404bb5a6922a@roeck-us.net>
Date: Fri, 1 Jul 2022 10:52:57 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Christophe JAILLET <christophe.jaillet@...adoo.fr>,
Ed Brindley <kernel@...davale.org>,
Denis Pauk <pauk.denis@...il.com>,
Jean Delvare <jdelvare@...e.com>
Cc: linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
linux-hwmon@...r.kernel.org
Subject: Re: [PATCH] hwmon: (asus_wmi_sensors) Save a few bytes of memory
On 7/1/22 10:47, Christophe JAILLET wrote:
> The first 'for' loop of asus_wmi_configure_sensor_setup() only computes
> the number and type of sensors that exist in the system.
>
> Here, the 'temp_sensor' structure is only used to store the data collected
> by asus_wmi_sensor_info(). There is no point in using a devm_ variant for
> this first allocation and it can be freed just after this initial loop.
>
> So use kzalloc()/kfree() to save a few bytes of memory that would be kept
> allocated for no good reason otherwise.
Then why isn't this just allocated on the stack ? The structure isn't _that_
large.
Guenter
>
> Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
> ---
> drivers/hwmon/asus_wmi_sensors.c | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/hwmon/asus_wmi_sensors.c b/drivers/hwmon/asus_wmi_sensors.c
> index 9e935e34c998..4873edad4996 100644
> --- a/drivers/hwmon/asus_wmi_sensors.c
> +++ b/drivers/hwmon/asus_wmi_sensors.c
> @@ -514,14 +514,16 @@ static int asus_wmi_configure_sensor_setup(struct device *dev,
> int i, idx;
> int err;
>
> - temp_sensor = devm_kcalloc(dev, 1, sizeof(*temp_sensor), GFP_KERNEL);
> + temp_sensor = kzalloc(sizeof(*temp_sensor), GFP_KERNEL);
> if (!temp_sensor)
> return -ENOMEM;
>
> for (i = 0; i < sensor_data->wmi.sensor_count; i++) {
> err = asus_wmi_sensor_info(i, temp_sensor);
> - if (err)
> + if (err) {
> + kfree(temp_sensor);
> return err;
> + }
>
> switch (temp_sensor->data_type) {
> case TEMPERATURE_C:
> @@ -536,6 +538,7 @@ static int asus_wmi_configure_sensor_setup(struct device *dev,
> break;
> }
> }
> + kfree(temp_sensor);
>
> if (nr_count[hwmon_temp])
> nr_count[hwmon_chip]++, nr_types++;
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