[PATCH] USB: gadgetfs: set "zero" flag for short control-IN response

This patch (as622) makes gadgetfs set the "zero" flag for control-IN
responses, when the length of the response is shorter than the length of
the request.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Acked-by: David Brownell <david-b@pacbell.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/gadget/inode.c

@@ -135,6 +135,7 @@ struct dev_data {
 					setup_out_ready : 1,
 					setup_out_error : 1,
 					setup_abort : 1;
+	unsigned			setup_wLength;
 
 	/* the rest is basically write-once */
 	struct usb_config_descriptor	*config, *hs_config;
@@ -942,6 +943,7 @@ static int setup_req (struct usb_ep *ep, struct usb_request *req, u16 len)
 	}
 	req->complete = ep0_complete;
 	req->length = len;
+	req->zero = 0;
 	return 0;
 }
 
@@ -1161,10 +1163,13 @@ ep0_write (struct file *fd, const char __user *buf, size_t len, loff_t *ptr)
 				spin_unlock_irq (&dev->lock);
 				if (copy_from_user (dev->req->buf, buf, len))
 					retval = -EFAULT;
-				else
+				else {
+					if (len < dev->setup_wLength)
+						dev->req->zero = 1;
 					retval = usb_ep_queue (
 						dev->gadget->ep0, dev->req,
 						GFP_KERNEL);
+				}
 				if (retval < 0) {
 					spin_lock_irq (&dev->lock);
 					clean_req (dev->gadget->ep0, dev->req);
@@ -1483,6 +1488,7 @@ gadgetfs_setup (struct usb_gadget *gadget, const struct usb_ctrlrequest *ctrl)
 delegate:
 			dev->setup_in = (ctrl->bRequestType & USB_DIR_IN)
 						? 1 : 0;
+			dev->setup_wLength = w_length;
 			dev->setup_out_ready = 0;
 			dev->setup_out_error = 0;
 			value = 0;