usb: gadget: udc-core: fix incompatibility with dummy-hcd

This patch (as1548) fixes a recently-introduced incompatibility
between the UDC core and the dummy-hcd driver. Commit
8ae8090c82eb407267001f75b3d256b3bd4ae691 (usb: gadget: udc-core: fix
asymmetric calls in remove_driver) moved the usb_gadget_udc_stop()
call in usb_gadget_remove_driver() below the usb_gadget_disconnect()
call.

As a result, usb_gadget_disconnect() gets called at a time when the
gadget driver believes it has been unbound but dummy-hcd believes
it has not. A nasty error ensues when dummy-hcd calls the gadget
driver's disconnect method a second time.

To fix the problem, this patch moves the gadget driver's unbind
notification after the usb_gadget_disconnect() call. Now nothing
happens between the two unbind notifications, so nothing goes wrong.

Signed-off-by: Alan Stern <[e-mail]>
Tested-by: Alexander Shishkin <[e-mail]>
Signed-off-by: Felipe Balbi <[e-mail]>

drivers/usb/gadget/udc-core.c

···
 
 	if (udc_is_newstyle(udc)) {
 		udc->driver->disconnect(udc->gadget);
-		udc->driver->unbind(udc->gadget);
 		usb_gadget_disconnect(udc->gadget);
+		udc->driver->unbind(udc->gadget);
 		usb_gadget_udc_stop(udc->gadget, udc->driver);
 	} else {
 		usb_gadget_stop(udc->gadget, udc->driver);