linux-kernel - [PATCH v4 4/4] drivers/thermal/exymos: Use guard notation when acquiring mutex

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Message-ID: <20250310143450.8276-5-linux.amoon@gmail.com>
Date: Mon, 10 Mar 2025 20:04:45 +0530
From: Anand Moon <linux.amoon@...il.com>
To: Bartlomiej Zolnierkiewicz <bzolnier@...il.com>,
	Krzysztof Kozlowski <krzk@...nel.org>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Zhang Rui <rui.zhang@...el.com>,
	Lukasz Luba <lukasz.luba@....com>,
	Alim Akhtar <alim.akhtar@...sung.com>,
	linux-pm@...r.kernel.org (open list:SAMSUNG THERMAL DRIVER),
	linux-samsung-soc@...r.kernel.org (open list:SAMSUNG THERMAL DRIVER),
	linux-arm-kernel@...ts.infradead.org (moderated list:ARM/SAMSUNG S3C, S5P AND EXYNOS ARM ARCHITECTURES),
	linux-kernel@...r.kernel.org (open list)
Cc: Anand Moon <linux.amoon@...il.com>
Subject: [PATCH v4 4/4] drivers/thermal/exymos: Use guard notation when acquiring mutex

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>
---
v4: used DEFINE_GUARD macro to guard exynos_tmu_data structure.
    However, incorporating guard(exynos_tmu_data)(data); results
    in a recursive deadlock with the mutex during initialization, as this
    data structure is common to all the code configurations of Exynos TMU
v3: New patch
---
 drivers/thermal/samsung/exynos_tmu.c | 25 +++++++++++--------------
 1 file changed, 11 insertions(+), 14 deletions(-)

diff --git a/drivers/thermal/samsung/exynos_tmu.c b/drivers/thermal/samsung/exynos_tmu.c
index a71cde0a4b17e..85f88c5e0f11c 100644
--- a/drivers/thermal/samsung/exynos_tmu.c
+++ b/drivers/thermal/samsung/exynos_tmu.c
@@ -12,6 +12,7 @@
  */
 
 #include <linux/clk.h>
+#include <linux/cleanup.h>
 #include <linux/io.h>
 #include <linux/interrupt.h>
 #include <linux/module.h>
@@ -199,6 +200,9 @@ struct exynos_tmu_data {
 	void (*tmu_clear_irqs)(struct exynos_tmu_data *data);
 };
 
+DEFINE_GUARD(exynos_tmu_data, struct exynos_tmu_data *,
+	     mutex_lock(&_T->lock), mutex_unlock(&_T->lock))
+
 /*
  * TMU treats temperature as a mapped temperature code.
  * The temperature is converted differently depending on the calibration type.
@@ -256,7 +260,7 @@ 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 +274,6 @@ 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 +295,12 @@ 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 +327,11 @@ 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 +646,7 @@ 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 +656,6 @@ 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 +720,10 @@ 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 +759,13 @@ 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 +985,7 @@ 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 +998,6 @@ 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;
 }
-- 
2.48.1