Re: [PATCH 17/22] Input: pegasus_notetaker - use guard notation when acquiring mutex

[Javier Carrasco <javier.carrasco.cruz@gmail.com>]

On 04/09/2024 06:48, 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/tablet/pegasus_notetaker.c | 86 +++++++++++++-----------
>  1 file changed, 48 insertions(+), 38 deletions(-)
> 
> diff --git a/drivers/input/tablet/pegasus_notetaker.c b/drivers/input/tablet/pegasus_notetaker.c
> index a68da2988f9c..e1dc8365bfe9 100644
> --- a/drivers/input/tablet/pegasus_notetaker.c
> +++ b/drivers/input/tablet/pegasus_notetaker.c
> @@ -214,6 +214,28 @@ static void pegasus_init(struct work_struct *work)
>  			error);
>  }
>  
> +static int __pegasus_open(struct pegasus *pegasus)
> +{
> +	int error;
> +
> +	guard(mutex)(&pegasus->pm_mutex);
> +
> +	pegasus->irq->dev = pegasus->usbdev;
> +	if (usb_submit_urb(pegasus->irq, GFP_KERNEL))
> +		return -EIO;
> +
> +	error = pegasus_set_mode(pegasus, PEN_MODE_XY, NOTETAKER_LED_MOUSE);
> +	if (error) {
> +		usb_kill_urb(pegasus->irq);
> +		cancel_work_sync(&pegasus->init);
> +		return error;
> +	}
> +
> +	pegasus->is_open = true;

Nit: blank line before return.

> +	return 0;
> +}

Nit: multiple blank lines.

> +
> +
>  static int pegasus_open(struct input_dev *dev)
>  {
>  	struct pegasus *pegasus = input_get_drvdata(dev);
> @@ -223,39 +245,25 @@ static int pegasus_open(struct input_dev *dev)
>  	if (error)
>  		return error;
>  
> -	mutex_lock(&pegasus->pm_mutex);
> -	pegasus->irq->dev = pegasus->usbdev;
> -	if (usb_submit_urb(pegasus->irq, GFP_KERNEL)) {
> -		error = -EIO;
> -		goto err_autopm_put;
> +	error = __pegasus_open(pegasus);
> +	if (error) {
> +		usb_autopm_put_interface(pegasus->intf);
> +		return error;
>  	}
>  
> -	error = pegasus_set_mode(pegasus, PEN_MODE_XY, NOTETAKER_LED_MOUSE);
> -	if (error)
> -		goto err_kill_urb;
> -
> -	pegasus->is_open = true;
> -	mutex_unlock(&pegasus->pm_mutex);
>  	return 0;
> -
> -err_kill_urb:
> -	usb_kill_urb(pegasus->irq);
> -	cancel_work_sync(&pegasus->init);
> -err_autopm_put:
> -	mutex_unlock(&pegasus->pm_mutex);
> -	usb_autopm_put_interface(pegasus->intf);
> -	return error;
>  }
>  
>  static void pegasus_close(struct input_dev *dev)
>  {
>  	struct pegasus *pegasus = input_get_drvdata(dev);
>  
> -	mutex_lock(&pegasus->pm_mutex);
> -	usb_kill_urb(pegasus->irq);
> -	cancel_work_sync(&pegasus->init);
> -	pegasus->is_open = false;
> -	mutex_unlock(&pegasus->pm_mutex);
> +	scoped_guard(mutex, &pegasus->pm_mutex) {
> +		usb_kill_urb(pegasus->irq);
> +		cancel_work_sync(&pegasus->init);
> +
> +		pegasus->is_open = false;
> +	}
>  
>  	usb_autopm_put_interface(pegasus->intf);
>  }
> @@ -411,10 +419,10 @@ static int pegasus_suspend(struct usb_interface *intf, pm_message_t message)
>  {
>  	struct pegasus *pegasus = usb_get_intfdata(intf);
>  
> -	mutex_lock(&pegasus->pm_mutex);
> +	guard(mutex)(&pegasus->pm_mutex);
> +
>  	usb_kill_urb(pegasus->irq);
>  	cancel_work_sync(&pegasus->init);
> -	mutex_unlock(&pegasus->pm_mutex);
>  
>  	return 0;
>  }
> @@ -422,31 +430,33 @@ static int pegasus_suspend(struct usb_interface *intf, pm_message_t message)
>  static int pegasus_resume(struct usb_interface *intf)
>  {
>  	struct pegasus *pegasus = usb_get_intfdata(intf);
> -	int retval = 0;
>  
> -	mutex_lock(&pegasus->pm_mutex);
> +	guard(mutex)(&pegasus->pm_mutex);
> +
>  	if (pegasus->is_open && usb_submit_urb(pegasus->irq, GFP_NOIO) < 0)
> -		retval = -EIO;
> -	mutex_unlock(&pegasus->pm_mutex);
> +		return -EIO;
>  
> -	return retval;
> +	return 0;
>  }
>  
>  static int pegasus_reset_resume(struct usb_interface *intf)
>  {
>  	struct pegasus *pegasus = usb_get_intfdata(intf);
> -	int retval = 0;
> +	int error;
> +
> +	guard(mutex)(&pegasus->pm_mutex);
>  
> -	mutex_lock(&pegasus->pm_mutex);
>  	if (pegasus->is_open) {
> -		retval = pegasus_set_mode(pegasus, PEN_MODE_XY,
> +		error = pegasus_set_mode(pegasus, PEN_MODE_XY,
>  					  NOTETAKER_LED_MOUSE);
> -		if (!retval && usb_submit_urb(pegasus->irq, GFP_NOIO) < 0)
> -			retval = -EIO;
> +		if (error)
> +			return error;
> +
> +		if (usb_submit_urb(pegasus->irq, GFP_NOIO) < 0)
> +			return -EIO;
>  	}
> -	mutex_unlock(&pegasus->pm_mutex);
>  
> -	return retval;
> +	return 0;
>  }
>  
>  static const struct usb_device_id pegasus_ids[] = {

Apart from the minor nitpicks,

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