linux-kernel - Re: [PATCH 5/5] input: twl6040-vibra: remove mutex

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Date:	Mon, 18 Apr 2016 14:20:48 -0700
From:	Dmitry Torokhov <dmitry.torokhov@...il.com>
To:	"H. Nikolaus Schaller" <hns@...delico.com>
Cc:	Fabio Estevam <fabio.estevam@...escale.com>,
	Peter Ujfalusi <peter.ujfalusi@...com>,
	linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
	kernel@...a-handheld.com, letux-kernel@...nphoenux.org
Subject: Re: [PATCH 5/5] input: twl6040-vibra: remove mutex

On Mon, Apr 18, 2016 at 09:55:41PM +0200, H. Nikolaus Schaller wrote:
> The mutex does not seem to be needed.

twl6040_vibra_suspend() and vibra_play_work() may run concurrently, no?

> twl4030-vibra doesn't
> use one either.

It probably should.

Thanks.

> 
> Signed-off-by: H. Nikolaus Schaller <hns@...delico.com>
> ---
>  drivers/input/misc/twl6040-vibra.c | 15 +--------------
>  1 file changed, 1 insertion(+), 14 deletions(-)
> 
> diff --git a/drivers/input/misc/twl6040-vibra.c b/drivers/input/misc/twl6040-vibra.c
> index 69c5940..dcc926b 100644
> --- a/drivers/input/misc/twl6040-vibra.c
> +++ b/drivers/input/misc/twl6040-vibra.c
> @@ -46,7 +46,7 @@ struct vibra_info {
>  	struct device *dev;
>  	struct input_dev *input_dev;
>  	struct work_struct play_work;
> -	struct mutex mutex;
> +
>  	int irq;
>  
>  	bool enabled;
> @@ -182,8 +182,6 @@ static void vibra_play_work(struct work_struct *work)
>  	struct vibra_info *info = container_of(work,
>  				struct vibra_info, play_work);
>  
> -	mutex_lock(&info->mutex);
> -
>  	if (info->weak_speed || info->strong_speed) {
>  		if (!info->enabled)
>  			twl6040_vibra_enable(info);
> @@ -192,7 +190,6 @@ static void vibra_play_work(struct work_struct *work)
>  	} else if (info->enabled)
>  		twl6040_vibra_disable(info);
>  
> -	mutex_unlock(&info->mutex);
>  }
>  
>  static int vibra_play(struct input_dev *input, void *data,
> @@ -223,12 +220,8 @@ static void twl6040_vibra_close(struct input_dev *input)
>  
>  	cancel_work_sync(&info->play_work);
>  
> -	mutex_lock(&info->mutex);
> -
>  	if (info->enabled)
>  		twl6040_vibra_disable(info);
> -
> -	mutex_unlock(&info->mutex);
>  }
>  
>  static int __maybe_unused twl6040_vibra_suspend(struct device *dev)
> @@ -236,13 +229,9 @@ static int __maybe_unused twl6040_vibra_suspend(struct device *dev)
>  	struct platform_device *pdev = to_platform_device(dev);
>  	struct vibra_info *info = platform_get_drvdata(pdev);
>  
> -	mutex_lock(&info->mutex);
> -
>  	if (info->enabled)
>  		twl6040_vibra_disable(info);
>  
> -	mutex_unlock(&info->mutex);
> -
>  	return 0;
>  }
>  
> @@ -301,8 +290,6 @@ static int twl6040_vibra_probe(struct platform_device *pdev)
>  		return -EINVAL;
>  	}
>  
> -	mutex_init(&info->mutex);
> -
>  	error = devm_request_threaded_irq(&pdev->dev, info->irq, NULL,
>  					  twl6040_vib_irq_handler,
>  					  IRQF_ONESHOT,
> -- 
> 2.7.3
> 

-- 
Dmitry