USB: cdc-wdm: no need to fill the in request URB every time it's submitted

Filling the same URB with the exact same data is pointless.  It can be filled
once and resubmitted.  And not doing buffer allocation and URB filling at the
same place only serves to hide size mismatch bugs

Signed-off-by: Bjørn Mork <bjorn@mork.no>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/class/cdc-wdm.c

@@ -159,11 +159,9 @@ static void wdm_int_callback(struct urb *urb)
 	int rv = 0;
 	int status = urb->status;
 	struct wdm_device *desc;
-	struct usb_ctrlrequest *req;
 	struct usb_cdc_notification *dr;
 
 	desc = urb->context;
-	req = desc->irq;
 	dr = (struct usb_cdc_notification *)desc->sbuf;
 
 	if (status) {
@@ -210,24 +208,6 @@ static void wdm_int_callback(struct urb *urb)
 		goto exit;
 	}
 
-	req->bRequestType = (USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE);
-	req->bRequest = USB_CDC_GET_ENCAPSULATED_RESPONSE;
-	req->wValue = 0;
-	req->wIndex = desc->inum;
-	req->wLength = cpu_to_le16(desc->wMaxCommand);
-
-	usb_fill_control_urb(
-		desc->response,
-		interface_to_usbdev(desc->intf),
-		/* using common endpoint 0 */
-		usb_rcvctrlpipe(interface_to_usbdev(desc->intf), 0),
-		(unsigned char *)req,
-		desc->inbuf,
-		desc->wMaxCommand,
-		wdm_in_callback,
-		desc
-	);
-	desc->response->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
 	spin_lock(&desc->iuspin);
 	clear_bit(WDM_READ, &desc->flags);
 	set_bit(WDM_RESPONDING, &desc->flags);
@@ -734,6 +714,25 @@ next_desc:
 	);
 	desc->validity->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
 
+	desc->irq->bRequestType = (USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE);
+	desc->irq->bRequest = USB_CDC_GET_ENCAPSULATED_RESPONSE;
+	desc->irq->wValue = 0;
+	desc->irq->wIndex = desc->inum;
+	desc->irq->wLength = cpu_to_le16(desc->wMaxCommand);
+
+	usb_fill_control_urb(
+		desc->response,
+		interface_to_usbdev(desc->intf),
+		/* using common endpoint 0 */
+		usb_rcvctrlpipe(interface_to_usbdev(desc->intf), 0),
+		(unsigned char *)desc->irq,
+		desc->inbuf,
+		desc->wMaxCommand,
+		wdm_in_callback,
+		desc
+	);
+	desc->response->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
+
 	usb_set_intfdata(intf, desc);
 	rv = usb_register_dev(intf, &wdm_class);
 	if (rv < 0)