linux-kernel - Re: [PATCH v3 4/4] drivers/thermal/exymos: Use guard notation when acquiring mutex

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Message-ID: <f44efd1a-1f6e-456d-9395-de2a55ef2279@arm.com>
Date: Fri, 28 Feb 2025 17:28:43 +0000
From: Lukasz Luba <lukasz.luba@....com>
To: Anand Moon <linux.amoon@...il.com>
Cc: Bartlomiej Zolnierkiewicz <bzolnier@...il.com>,
 "open list:SAMSUNG THERMAL DRIVER" <linux-samsung-soc@...r.kernel.org>,
 "open list:SAMSUNG THERMAL DRIVER" <linux-pm@...r.kernel.org>,
 Alim Akhtar <alim.akhtar@...sung.com>,
 Daniel Lezcano <daniel.lezcano@...aro.org>,
 open list <linux-kernel@...r.kernel.org>,
 "moderated list:ARM/SAMSUNG S3C, S5P AND EXYNOS ARM ARCHITECTURES"
 <linux-arm-kernel@...ts.infradead.org>, Zhang Rui <rui.zhang@...el.com>,
 Krzysztof Kozlowski <krzk@...nel.org>, "Rafael J. Wysocki"
 <rafael@...nel.org>
Subject: Re: [PATCH v3 4/4] drivers/thermal/exymos: Use guard notation when
 acquiring mutex



On 2/16/25 19:58, Anand Moon wrote:
> Using guard notation makes the code more compact and error handling
> more robust by ensuring that mutexes are released in all code paths
> when control leaves critical section.
> 
> Signed-off-by: Anand Moon <linux.amoon@...il.com>
> ---
> v3: new patch
> ---
>   drivers/thermal/samsung/exynos_tmu.c | 21 +++++++--------------
>   1 file changed, 7 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/thermal/samsung/exynos_tmu.c b/drivers/thermal/samsung/exynos_tmu.c
> index fe090c1a93ab..a34ba3858d64 100644
> --- a/drivers/thermal/samsung/exynos_tmu.c
> +++ b/drivers/thermal/samsung/exynos_tmu.c
> @@ -256,7 +256,7 @@ static int exynos_tmu_initialize(struct platform_device *pdev)
>   	unsigned int status;
>   	int ret = 0;
>   
> -	mutex_lock(&data->lock);
> +	guard(mutex)(&data->lock);
>   	clk_enable(data->clk);
>   	clk_enable(data->clk_sec);
>   
> @@ -270,7 +270,6 @@ static int exynos_tmu_initialize(struct platform_device *pdev)
>   
>   	clk_disable(data->clk_sec);
>   	clk_disable(data->clk);
> -	mutex_unlock(&data->lock);
>   
>   	return ret;
>   }
> @@ -292,13 +291,12 @@ static int exynos_thermal_zone_configure(struct platform_device *pdev)
>   		return ret;
>   	}
>   
> -	mutex_lock(&data->lock);
> +	guard(mutex)(&data->lock);
>   	clk_enable(data->clk);
>   
>   	data->tmu_set_crit_temp(data, temp / MCELSIUS);
>   
>   	clk_disable(data->clk);
> -	mutex_unlock(&data->lock);
>   
>   	return 0;
>   }
> @@ -325,12 +323,11 @@ static void exynos_tmu_control(struct platform_device *pdev, bool on)
>   {
>   	struct exynos_tmu_data *data = platform_get_drvdata(pdev);
>   
> -	mutex_lock(&data->lock);
> +	guard(mutex)(&data->lock);
>   	clk_enable(data->clk);
>   	data->tmu_control(pdev, on);
>   	data->enabled = on;
>   	clk_disable(data->clk);
> -	mutex_unlock(&data->lock);
>   }
>   
>   static void exynos_tmu_update_bit(struct exynos_tmu_data *data, int reg_off,
> @@ -645,7 +642,7 @@ static int exynos_get_temp(struct thermal_zone_device *tz, int *temp)
>   		 */
>   		return -EAGAIN;
>   
> -	mutex_lock(&data->lock);
> +	guard(mutex)(&data->lock);
>   	clk_enable(data->clk);
>   
>   	value = data->tmu_read(data);
> @@ -655,7 +652,6 @@ static int exynos_get_temp(struct thermal_zone_device *tz, int *temp)
>   		*temp = code_to_temp(data, value) * MCELSIUS;
>   
>   	clk_disable(data->clk);
> -	mutex_unlock(&data->lock);
>   
>   	return ret;
>   }
> @@ -720,11 +716,10 @@ static int exynos_tmu_set_emulation(struct thermal_zone_device *tz, int temp)
>   	if (temp && temp < MCELSIUS)
>   		goto out;
>   
> -	mutex_lock(&data->lock);
> +	guard(mutex)(&data->lock);
>   	clk_enable(data->clk);
>   	data->tmu_set_emulation(data, temp);
>   	clk_disable(data->clk);
> -	mutex_unlock(&data->lock);
>   	return 0;
>   out:
>   	return ret;
> @@ -760,14 +755,13 @@ static irqreturn_t exynos_tmu_threaded_irq(int irq, void *id)
>   
>   	thermal_zone_device_update(data->tzd, THERMAL_EVENT_UNSPECIFIED);
>   
> -	mutex_lock(&data->lock);
> +	guard(mutex)(&data->lock);
>   	clk_enable(data->clk);
>   
>   	/* TODO: take action based on particular interrupt */
>   	data->tmu_clear_irqs(data);
>   
>   	clk_disable(data->clk);
> -	mutex_unlock(&data->lock);
>   
>   	return IRQ_HANDLED;
>   }
> @@ -987,7 +981,7 @@ static int exynos_set_trips(struct thermal_zone_device *tz, int low, int high)
>   {
>   	struct exynos_tmu_data *data = thermal_zone_device_priv(tz);
>   
> -	mutex_lock(&data->lock);
> +	guard(mutex)(&data->lock);
>   	clk_enable(data->clk);
>   
>   	if (low > INT_MIN)
> @@ -1000,7 +994,6 @@ static int exynos_set_trips(struct thermal_zone_device *tz, int low, int high)
>   		data->tmu_disable_high(data);
>   
>   	clk_disable(data->clk);
> -	mutex_unlock(&data->lock);
>   
>   	return 0;
>   }

IMO you should be able to even use something like we have
core framework:

guard(thermal_zone)(tz);

Your mutex name is simply 'lock' in the struct exynos_tmu_data
so you should be able to leverage this by:

guard(exynos_tmu_data)(data);

Please try that.