linux-kernel - Re: [RESEND PATCH 4/6] input: pegasus_notetaker: do not rely on input

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Date:   Sat, 17 Mar 2018 11:11:05 -0700
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Marcus Folkesson <marcus.folkesson@...il.com>
Cc:     Arvind Yadav <arvind.yadav.cs@...il.com>,
        linux-input@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [RESEND PATCH 4/6] input: pegasus_notetaker: do not rely on
 input_dev->users

On Wed, Feb 28, 2018 at 02:38:01PM +0100, Marcus Folkesson wrote:
> If the device is unused and suspended, a call to open will cause the
> device to autoresume through the call to usb_autopm_get_interface().
> 
> input_dev->users is already incremented by the input subsystem,
> therefore this expression will always be evaluated to true:
> 
> 	if (pegasus->dev->users && usb_submit_urb(pegasus->irq, GFP_NOIO) < 0)
> 		retval = -EIO;
> 
> The same URB will then be fail when resubmitted in pegasus_open().
> 
> Introduce pegasus->is_open to keep track of the state instead.
> 
> Signed-off-by: Marcus Folkesson <marcus.folkesson@...il.com>

Applied, thank you.

> ---
>  drivers/input/tablet/pegasus_notetaker.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/input/tablet/pegasus_notetaker.c b/drivers/input/tablet/pegasus_notetaker.c
> index 9ab1ed5e20e7..74c93e09c337 100644
> --- a/drivers/input/tablet/pegasus_notetaker.c
> +++ b/drivers/input/tablet/pegasus_notetaker.c
> @@ -80,6 +80,7 @@ struct pegasus {
>  
>  	/* serialize access to open/suspend */
>  	struct mutex pm_mutex;
> +	bool is_open;
>  
>  	char name[128];
>  	char phys[64];
> @@ -232,6 +233,7 @@ static int pegasus_open(struct input_dev *dev)
>  	if (error)
>  		goto err_kill_urb;
>  
> +	pegasus->is_open = 1;
>  	mutex_unlock(&pegasus->pm_mutex);
>  	return 0;
>  
> @@ -251,6 +253,7 @@ static void pegasus_close(struct input_dev *dev)
>  	mutex_lock(&pegasus->pm_mutex);
>  	usb_kill_urb(pegasus->irq);
>  	cancel_work_sync(&pegasus->init);
> +	pegasus->is_open = 0;
>  	mutex_unlock(&pegasus->pm_mutex);
>  
>  	usb_autopm_put_interface(pegasus->intf);
> @@ -415,7 +418,7 @@ static int pegasus_resume(struct usb_interface *intf)
>  	int retval = 0;
>  
>  	mutex_lock(&pegasus->pm_mutex);
> -	if (pegasus->dev->users && usb_submit_urb(pegasus->irq, GFP_NOIO) < 0)
> +	if (pegasus->is_open && usb_submit_urb(pegasus->irq, GFP_NOIO) < 0)
>  		retval = -EIO;
>  	mutex_unlock(&pegasus->pm_mutex);
>  
> @@ -428,7 +431,7 @@ static int pegasus_reset_resume(struct usb_interface *intf)
>  	int retval = 0;
>  
>  	mutex_lock(&pegasus->pm_mutex);
> -	if (pegasus->dev->users) {
> +	if (pegasus->is_open) {
>  		retval = pegasus_set_mode(pegasus, PEN_MODE_XY,
>  					  NOTETAKER_LED_MOUSE);
>  		if (!retval && usb_submit_urb(pegasus->irq, GFP_NOIO) < 0)
> -- 
> 2.16.2
> 

-- 
Dmitry