[PATCH v2] tablet: acecad: update the reference count of the usb interface structure

[PATCH v2] tablet: acecad: update the reference count of the usb interface structure

[Salah Triki]

Based on the following documentation usb_get_inf(), use usb_get_intf()
and usb_put_intf() in order to update the reference count of the usb
interface structure.

Documentation of usb_get_inf():

[quote]
Each live reference to a interface must be refcounted.

Drivers for USB interfaces should normally record such references
in their probe methods, when they bind to an interface, and release them
by calling usb_put_intf, in their disconnect methods.
[/quote]

Signed-off-by: Salah Triki <salah.triki@gmail.com>
---
Change since v1:
	Modification of the description

 drivers/input/tablet/acecad.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/input/tablet/acecad.c b/drivers/input/tablet/acecad.c
index a38d1fe97334..85fe134a30ee 100644
--- a/drivers/input/tablet/acecad.c
+++ b/drivers/input/tablet/acecad.c
@@ -151,7 +151,7 @@ static int usb_acecad_probe(struct usb_interface *intf, const struct usb_device_
 		goto fail2;
 	}
 
-	acecad->intf = intf;
+	acecad->intf = usb_get_intf(intf);
 	acecad->input = input_dev;
 
 	if (dev->manufacturer)
@@ -236,6 +236,9 @@ static void usb_acecad_disconnect(struct usb_interface *intf)
 	input_unregister_device(acecad->input);
 	usb_free_urb(acecad->irq);
 	usb_free_coherent(udev, 8, acecad->data, acecad->data_dma);
+
+	usb_put_intf(acecad->intf);
+
 	kfree(acecad);
 }
 
-- 
2.25.1

Re: [PATCH v2] tablet: acecad: update the reference count of the usb interface structure

[Dan Carpenter]

On Sat, Jul 31, 2021 at 05:09:38PM +0100, Salah Triki wrote:
>  drivers/input/tablet/acecad.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/input/tablet/acecad.c b/drivers/input/tablet/acecad.c
> index a38d1fe97334..85fe134a30ee 100644
> --- a/drivers/input/tablet/acecad.c
> +++ b/drivers/input/tablet/acecad.c
> @@ -151,7 +151,7 @@ static int usb_acecad_probe(struct usb_interface *intf, const struct usb_device_
>  		goto fail2;
>  	}
>  
> -	acecad->intf = intf;
> +	acecad->intf = usb_get_intf(intf);
>  	acecad->input = input_dev;
>  
>  	if (dev->manufacturer)

As I mentioned earlier, you need to drop the reference if
input_register_device() fails.

regards,
dan carpenter

Re: [PATCH v2] tablet: acecad: update the reference count of the usb interface structure

[Greg Kroah-Hartman]

On Wed, Aug 04, 2021 at 01:58:38PM +0300, Dan Carpenter wrote:
> On Sat, Jul 31, 2021 at 05:09:38PM +0100, Salah Triki wrote:
> >  drivers/input/tablet/acecad.c | 5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/input/tablet/acecad.c b/drivers/input/tablet/acecad.c
> > index a38d1fe97334..85fe134a30ee 100644
> > --- a/drivers/input/tablet/acecad.c
> > +++ b/drivers/input/tablet/acecad.c
> > @@ -151,7 +151,7 @@ static int usb_acecad_probe(struct usb_interface *intf, const struct usb_device_
> >  		goto fail2;
> >  	}
> >  
> > -	acecad->intf = intf;
> > +	acecad->intf = usb_get_intf(intf);
> >  	acecad->input = input_dev;
> >  
> >  	if (dev->manufacturer)
> 
> As I mentioned earlier, you need to drop the reference if
> input_register_device() fails.

Also as mentioned in other threads, this is not needed at all.

Re: [PATCH v2] tablet: acecad: update the reference count of the usb interface structure

[Dan Carpenter]

On Sat, Jul 31, 2021 at 05:09:38PM +0100, Salah Triki wrote:
> Based on the following documentation usb_get_inf(), use usb_get_intf()
> and usb_put_intf() in order to update the reference count of the usb
> interface structure.
> 
> Documentation of usb_get_inf():
> 
> [quote]
> Each live reference to a interface must be refcounted.
> 
> Drivers for USB interfaces should normally record such references
> in their probe methods, when they bind to an interface, and release them
> by calling usb_put_intf, in their disconnect methods.
> [/quote]
> 
> Signed-off-by: Salah Triki <salah.triki@gmail.com>

Also add a Fixes tag.

regards,
dan carpenter