Re: [PATCH] usb: gadget: udc-core: call udc_stop() before gadget unbind

[Peter Chen <peter.chen@freescale.com>]

On Fri, Dec 12, 2014 at 02:17:28PM +0100, Robert Baldyga wrote:
> As usb function drivers assumes that all usb request will be completed
> before function unbind call, we should supply such behavior. In some
> cases ep_disable() won't kill all request effectively, because some
> IN requests can be in running state. In such situation it's possible
> to have unbind function called before last request completion, which
> can cause problems.

Doesn't the function's disable/unbind should call usb_ep_dequeue to make
sure the transfer has ended?

.udc_stop may stop the controller, and .unbind may still visit hardware.

> 
> For example unbinding f_ecm function while request on 'notify' endpoint
> is not completed, ends up NULL pointer dereference in unbind() function.
> 
> usb_gadget_udc_stop() call causes completion of all requests so if it's
> called before gadget unbind there is no risk that some of requests will
> stay uncompleted.
> 
> Signed-off-by: Robert Baldyga <r.baldyga@samsung.com>
> ---
>  drivers/usb/gadget/udc/udc-core.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/gadget/udc/udc-core.c b/drivers/usb/gadget/udc/udc-core.c
> index e31d574..6f0d233 100644
> --- a/drivers/usb/gadget/udc/udc-core.c
> +++ b/drivers/usb/gadget/udc/udc-core.c
> @@ -331,8 +331,8 @@ static void usb_gadget_remove_driver(struct usb_udc *udc)
>  
>  	usb_gadget_disconnect(udc->gadget);
>  	udc->driver->disconnect(udc->gadget);
> -	udc->driver->unbind(udc->gadget);
>  	usb_gadget_udc_stop(udc);
> +	udc->driver->unbind(udc->gadget);
>  
>  	udc->driver = NULL;
>  	udc->dev.driver = NULL;
> -- 
> 1.9.1
> 

-- 

Best Regards,
Peter Chen