linux-kernel - Re: [PATCH] watchdog: mena21_wdt: Drop unnecessary mutex lock

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Message-ID: <20180508144822.GA11268@roeck-us.net>
Date:   Tue, 8 May 2018 07:48:22 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Jia-Ju Bai <baijiaju1990@...il.com>
Cc:     morbidrsa@...il.com, wim@...ux-watchdog.org,
        linux-watchdog@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] watchdog: mena21_wdt: Drop unnecessary mutex lock

On Tue, May 08, 2018 at 03:12:06PM +0800, Jia-Ju Bai wrote:
> There is already a mutex in the watchdog core which serializes
> calls to the various API functions. 
> So the mutex lock "drv->lock" is unnecessary and can be dropped.
> 
> Signed-off-by: Jia-Ju Bai <baijiaju1990@...il.com>

Reviewed-by: Guenter Roeck <linux@...ck-us.net>

> ---
>  drivers/watchdog/mena21_wdt.c | 18 ------------------
>  1 file changed, 18 deletions(-)
> 
> diff --git a/drivers/watchdog/mena21_wdt.c b/drivers/watchdog/mena21_wdt.c
> index 25d5d2b8cfbe..0be7f50e8ff9 100644
> --- a/drivers/watchdog/mena21_wdt.c
> +++ b/drivers/watchdog/mena21_wdt.c
> @@ -31,7 +31,6 @@ enum a21_wdt_gpios {
>  
>  struct a21_wdt_drv {
>  	struct watchdog_device wdt;
> -	struct mutex lock;
>  	unsigned gpios[NUM_GPIOS];
>  };
>  
> @@ -55,12 +54,8 @@ static int a21_wdt_start(struct watchdog_device *wdt)
>  {
>  	struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
>  
> -	mutex_lock(&drv->lock);
> -
>  	gpio_set_value(drv->gpios[GPIO_WD_ENAB], 1);
>  
> -	mutex_unlock(&drv->lock);
> -
>  	return 0;
>  }
>  
> @@ -68,12 +63,8 @@ static int a21_wdt_stop(struct watchdog_device *wdt)
>  {
>  	struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
>  
> -	mutex_lock(&drv->lock);
> -
>  	gpio_set_value(drv->gpios[GPIO_WD_ENAB], 0);
>  
> -	mutex_unlock(&drv->lock);
> -
>  	return 0;
>  }
>  
> @@ -81,14 +72,10 @@ static int a21_wdt_ping(struct watchdog_device *wdt)
>  {
>  	struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
>  
> -	mutex_lock(&drv->lock);
> -
>  	gpio_set_value(drv->gpios[GPIO_WD_TRIG], 0);
>  	ndelay(10);
>  	gpio_set_value(drv->gpios[GPIO_WD_TRIG], 1);
>  
> -	mutex_unlock(&drv->lock);
> -
>  	return 0;
>  }
>  
> @@ -108,8 +95,6 @@ static int a21_wdt_set_timeout(struct watchdog_device *wdt,
>  		return -EINVAL;
>  	}
>  
> -	mutex_lock(&drv->lock);
> -
>  	if (timeout == 1)
>  		gpio_set_value(drv->gpios[GPIO_WD_FAST], 1);
>  	else
> @@ -117,8 +102,6 @@ static int a21_wdt_set_timeout(struct watchdog_device *wdt,
>  
>  	wdt->timeout = timeout;
>  
> -	mutex_unlock(&drv->lock);
> -
>  	return 0;
>  }
>  
> @@ -191,7 +174,6 @@ static int a21_wdt_probe(struct platform_device *pdev)
>  			return ret;
>  	}
>  
> -	mutex_init(&drv->lock);
>  	watchdog_init_timeout(&a21_wdt, 30, &pdev->dev);
>  	watchdog_set_nowayout(&a21_wdt, nowayout);
>  	watchdog_set_drvdata(&a21_wdt, drv);
> -- 
> 2.17.0
> 
> --
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