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: Dmitry Torokhov <dmitry.torokhov@gmail.com>
---
 drivers/input/misc/regulator-haptic.c | 23 ++++++++---------------
 1 file changed, 8 insertions(+), 15 deletions(-)

diff --git a/drivers/input/misc/regulator-haptic.c b/drivers/input/misc/regulator-haptic.c
index 02f73b7c0462..41af6aefaa07 100644
--- a/drivers/input/misc/regulator-haptic.c
+++ b/drivers/input/misc/regulator-haptic.c
@@ -83,12 +83,10 @@ static void regulator_haptic_work(struct work_struct *work)
 	struct regulator_haptic *haptic = container_of(work,
 					struct regulator_haptic, work);
 
-	mutex_lock(&haptic->mutex);
+	guard(mutex)(&haptic->mutex);
 
 	if (!haptic->suspended)
 		regulator_haptic_set_voltage(haptic, haptic->magnitude);
-
-	mutex_unlock(&haptic->mutex);
 }
 
 static int regulator_haptic_play_effect(struct input_dev *input, void *data,
@@ -207,17 +205,14 @@ static int regulator_haptic_suspend(struct device *dev)
 	struct regulator_haptic *haptic = platform_get_drvdata(pdev);
 	int error;
 
-	error = mutex_lock_interruptible(&haptic->mutex);
-	if (error)
-		return error;
-
-	regulator_haptic_set_voltage(haptic, 0);
-
-	haptic->suspended = true;
+	scoped_guard(mutex_intr, &haptic->mutex) {
+		regulator_haptic_set_voltage(haptic, 0);
+		haptic->suspended = true;
 
-	mutex_unlock(&haptic->mutex);
+		return 0;
+	}
 
-	return 0;
+	return -EINTR;
 }
 
 static int regulator_haptic_resume(struct device *dev)
@@ -226,7 +221,7 @@ static int regulator_haptic_resume(struct device *dev)
 	struct regulator_haptic *haptic = platform_get_drvdata(pdev);
 	unsigned int magnitude;
 
-	mutex_lock(&haptic->mutex);
+	guard(mutex)(&haptic->mutex);
 
 	haptic->suspended = false;
 
@@ -234,8 +229,6 @@ static int regulator_haptic_resume(struct device *dev)
 	if (magnitude)
 		regulator_haptic_set_voltage(haptic, magnitude);
 
-	mutex_unlock(&haptic->mutex);
-
 	return 0;
 }
 
-- 
2.46.0.469.g59c65b2a67-goog

Hi Dmitry,

kernel test robot noticed the following build warnings:

[auto build test WARNING on dtor-input/next]
[also build test WARNING on dtor-input/for-linus hid/for-next linus/master v6.11-rc6 next-20240906]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Dmitry-Torokhov/Input-ad714x-use-guard-notation-when-acquiring-mutex/20240905-085752
base:   https://git.kernel.org/pub/scm/linux/kernel/git/dtor/input.git next
patch link:    https://lore.kernel.org/r/20240904044922.1049488-1-dmitry.torokhov%40gmail.com
patch subject: [PATCH 20/22] Input: regulator-haptic - use guard notation when acquiring mutex
config: x86_64-buildonly-randconfig-001-20240907 (https://download.01.org/0day-ci/archive/20240907/202409071004.IhekZKbM-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240907/202409071004.IhekZKbM-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202409071004.IhekZKbM-lkp@intel.com/

All warnings (new ones prefixed by >>):

   drivers/input/misc/regulator-haptic.c: In function 'regulator_haptic_suspend':
>> drivers/input/misc/regulator-haptic.c:206:13: warning: unused variable 'error' [-Wunused-variable]
     206 |         int error;
         |             ^~~~~


vim +/error +206 drivers/input/misc/regulator-haptic.c

d64cb71bede87d Jaewon Kim       2014-12-17  201  
1a3e6c1ee47d00 Jonathan Cameron 2023-01-02  202  static int regulator_haptic_suspend(struct device *dev)
d64cb71bede87d Jaewon Kim       2014-12-17  203  {
d64cb71bede87d Jaewon Kim       2014-12-17  204  	struct platform_device *pdev = to_platform_device(dev);
d64cb71bede87d Jaewon Kim       2014-12-17  205  	struct regulator_haptic *haptic = platform_get_drvdata(pdev);
d64cb71bede87d Jaewon Kim       2014-12-17 @206  	int error;
d64cb71bede87d Jaewon Kim       2014-12-17  207  
aaa0758ff6b5c4 Dmitry Torokhov  2024-09-03  208  	scoped_guard(mutex_intr, &haptic->mutex) {
d64cb71bede87d Jaewon Kim       2014-12-17  209  		regulator_haptic_set_voltage(haptic, 0);
d64cb71bede87d Jaewon Kim       2014-12-17  210  		haptic->suspended = true;
d64cb71bede87d Jaewon Kim       2014-12-17  211  
d64cb71bede87d Jaewon Kim       2014-12-17  212  		return 0;
d64cb71bede87d Jaewon Kim       2014-12-17  213  	}
d64cb71bede87d Jaewon Kim       2014-12-17  214  
aaa0758ff6b5c4 Dmitry Torokhov  2024-09-03  215  	return -EINTR;
aaa0758ff6b5c4 Dmitry Torokhov  2024-09-03  216  }
aaa0758ff6b5c4 Dmitry Torokhov  2024-09-03  217  

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

On 04/09/2024 06:49, Dmitry Torokhov 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: Dmitry Torokhov <dmitry.torokhov@gmail.com>
> ---
>  drivers/input/misc/regulator-haptic.c | 23 ++++++++---------------
>  1 file changed, 8 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/input/misc/regulator-haptic.c b/drivers/input/misc/regulator-haptic.c
> index 02f73b7c0462..41af6aefaa07 100644
> --- a/drivers/input/misc/regulator-haptic.c
> +++ b/drivers/input/misc/regulator-haptic.c
> @@ -83,12 +83,10 @@ static void regulator_haptic_work(struct work_struct *work)
>  	struct regulator_haptic *haptic = container_of(work,
>  					struct regulator_haptic, work);
>  
> -	mutex_lock(&haptic->mutex);
> +	guard(mutex)(&haptic->mutex);
>  
>  	if (!haptic->suspended)
>  		regulator_haptic_set_voltage(haptic, haptic->magnitude);
> -
> -	mutex_unlock(&haptic->mutex);
>  }
>  
>  static int regulator_haptic_play_effect(struct input_dev *input, void *data,
> @@ -207,17 +205,14 @@ static int regulator_haptic_suspend(struct device *dev)
>  	struct regulator_haptic *haptic = platform_get_drvdata(pdev);

error became an unused variable and can be dropped.

>  	int error;
>  
> -	error = mutex_lock_interruptible(&haptic->mutex);
> -	if (error)
> -		return error;
> -
> -	regulator_haptic_set_voltage(haptic, 0);
> -
> -	haptic->suspended = true;
> +	scoped_guard(mutex_intr, &haptic->mutex) {
> +		regulator_haptic_set_voltage(haptic, 0);
> +		haptic->suspended = true;
>  
> -	mutex_unlock(&haptic->mutex);
> +		return 0;
> +	}
>  
> -	return 0;
> +	return -EINTR;
>  }
>  
>  static int regulator_haptic_resume(struct device *dev)
> @@ -226,7 +221,7 @@ static int regulator_haptic_resume(struct device *dev)
>  	struct regulator_haptic *haptic = platform_get_drvdata(pdev);
>  	unsigned int magnitude;
>  
> -	mutex_lock(&haptic->mutex);
> +	guard(mutex)(&haptic->mutex);
>  
>  	haptic->suspended = false;
>  
> @@ -234,8 +229,6 @@ static int regulator_haptic_resume(struct device *dev)
>  	if (magnitude)
>  		regulator_haptic_set_voltage(haptic, magnitude);
>  
> -	mutex_unlock(&haptic->mutex);
> -
>  	return 0;
>  }
>

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: Dmitry Torokhov <dmitry.torokhov@gmail.com>
---

v2: drop no linger used "error" variable in regulator_haptic_suspend()

 drivers/input/misc/regulator-haptic.c |   24 ++++++++----------------
 1 file changed, 8 insertions(+), 16 deletions(-)

diff --git a/drivers/input/misc/regulator-haptic.c b/drivers/input/misc/regulator-haptic.c
index 02f73b7c0462..3666ba6d1f30 100644
--- a/drivers/input/misc/regulator-haptic.c
+++ b/drivers/input/misc/regulator-haptic.c
@@ -83,12 +83,10 @@ static void regulator_haptic_work(struct work_struct *work)
 	struct regulator_haptic *haptic = container_of(work,
 					struct regulator_haptic, work);
 
-	mutex_lock(&haptic->mutex);
+	guard(mutex)(&haptic->mutex);
 
 	if (!haptic->suspended)
 		regulator_haptic_set_voltage(haptic, haptic->magnitude);
-
-	mutex_unlock(&haptic->mutex);
 }
 
 static int regulator_haptic_play_effect(struct input_dev *input, void *data,
@@ -205,19 +203,15 @@ static int regulator_haptic_suspend(struct device *dev)
 {
 	struct platform_device *pdev = to_platform_device(dev);
 	struct regulator_haptic *haptic = platform_get_drvdata(pdev);
-	int error;
 
-	error = mutex_lock_interruptible(&haptic->mutex);
-	if (error)
-		return error;
-
-	regulator_haptic_set_voltage(haptic, 0);
+	scoped_guard(mutex_intr, &haptic->mutex) {
+		regulator_haptic_set_voltage(haptic, 0);
+		haptic->suspended = true;
 
-	haptic->suspended = true;
-
-	mutex_unlock(&haptic->mutex);
+		return 0;
+	}
 
-	return 0;
+	return -EINTR;
 }
 
 static int regulator_haptic_resume(struct device *dev)
@@ -226,7 +220,7 @@ static int regulator_haptic_resume(struct device *dev)
 	struct regulator_haptic *haptic = platform_get_drvdata(pdev);
 	unsigned int magnitude;
 
-	mutex_lock(&haptic->mutex);
+	guard(mutex)(&haptic->mutex);
 
 	haptic->suspended = false;
 
@@ -234,8 +228,6 @@ static int regulator_haptic_resume(struct device *dev)
 	if (magnitude)
 		regulator_haptic_set_voltage(haptic, magnitude);
 
-	mutex_unlock(&haptic->mutex);
-
 	return 0;
 }

On 04/09/2024 22:55, Dmitry Torokhov 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: Dmitry Torokhov <dmitry.torokhov@gmail.com>
> ---
> 
> v2: drop no linger used "error" variable in regulator_haptic_suspend()
> 
>  drivers/input/misc/regulator-haptic.c |   24 ++++++++----------------
>  1 file changed, 8 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/input/misc/regulator-haptic.c b/drivers/input/misc/regulator-haptic.c
> index 02f73b7c0462..3666ba6d1f30 100644
> --- a/drivers/input/misc/regulator-haptic.c
> +++ b/drivers/input/misc/regulator-haptic.c
> @@ -83,12 +83,10 @@ static void regulator_haptic_work(struct work_struct *work)
>  	struct regulator_haptic *haptic = container_of(work,
>  					struct regulator_haptic, work);
>  
> -	mutex_lock(&haptic->mutex);
> +	guard(mutex)(&haptic->mutex);
>  
>  	if (!haptic->suspended)
>  		regulator_haptic_set_voltage(haptic, haptic->magnitude);
> -
> -	mutex_unlock(&haptic->mutex);
>  }
>  
>  static int regulator_haptic_play_effect(struct input_dev *input, void *data,
> @@ -205,19 +203,15 @@ static int regulator_haptic_suspend(struct device *dev)
>  {
>  	struct platform_device *pdev = to_platform_device(dev);
>  	struct regulator_haptic *haptic = platform_get_drvdata(pdev);
> -	int error;
>  
> -	error = mutex_lock_interruptible(&haptic->mutex);
> -	if (error)
> -		return error;
> -
> -	regulator_haptic_set_voltage(haptic, 0);
> +	scoped_guard(mutex_intr, &haptic->mutex) {
> +		regulator_haptic_set_voltage(haptic, 0);
> +		haptic->suspended = true;
>  
> -	haptic->suspended = true;
> -
> -	mutex_unlock(&haptic->mutex);
> +		return 0;
> +	}
>  
> -	return 0;
> +	return -EINTR;
>  }
>  
>  static int regulator_haptic_resume(struct device *dev)
> @@ -226,7 +220,7 @@ static int regulator_haptic_resume(struct device *dev)
>  	struct regulator_haptic *haptic = platform_get_drvdata(pdev);
>  	unsigned int magnitude;
>  
> -	mutex_lock(&haptic->mutex);
> +	guard(mutex)(&haptic->mutex);
>  
>  	haptic->suspended = false;
>  
> @@ -234,8 +228,6 @@ static int regulator_haptic_resume(struct device *dev)
>  	if (magnitude)
>  		regulator_haptic_set_voltage(haptic, magnitude);
>  
> -	mutex_unlock(&haptic->mutex);
> -
>  	return 0;
>  }
>  

Reviewed-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>