USB: address FIXME in usbnet w.r.t drivers claiming multiple interfaces

This fixes the issue of drivers claiming multiple interfaces. Operations
are stopped as soon as an interface is suspend and resumed only as
all interfaces have been resumed.
Signed-off-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/net/usb/usbnet.c

@@ -1252,20 +1252,23 @@ EXPORT_SYMBOL_GPL(usbnet_probe);
 
 /*-------------------------------------------------------------------------*/
 
-/* FIXME these suspend/resume methods assume non-CDC style
- * devices, with only one interface.
+/*
+ * suspend the whole driver as soon as the first interface is suspended
+ * resume only when the last interface is resumed
  */
 
 int usbnet_suspend (struct usb_interface *intf, pm_message_t message)
 {
 	struct usbnet		*dev = usb_get_intfdata(intf);
 
+	if (!dev->suspend_count++) {
 		/* accelerate emptying of the rx and queues, to avoid
 		 * having everything error out.
 		 */
 		netif_device_detach (dev->net);
 		(void) unlink_urbs (dev, &dev->rxq);
 		(void) unlink_urbs (dev, &dev->txq);
+	}
 	return 0;
 }
 EXPORT_SYMBOL_GPL(usbnet_suspend);
@@ -1274,8 +1277,10 @@ int usbnet_resume (struct usb_interface *intf)
 {
 	struct usbnet		*dev = usb_get_intfdata(intf);
 
+	if (!--dev->suspend_count) {
 		netif_device_attach (dev->net);
 		tasklet_schedule (&dev->bh);
+	}
 	return 0;
 }
 EXPORT_SYMBOL_GPL(usbnet_resume);

drivers/net/usb/usbnet.h

@@ -32,6 +32,7 @@ struct usbnet {
 	const char		*driver_name;
 	wait_queue_head_t	*wait;
 	struct mutex		phy_mutex;
+	unsigned char		suspend_count;
 
 	/* i/o info: pipes etc */
 	unsigned		in, out;