diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index 06e7023..e5a0171 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -1401,6 +1401,7 @@
 	u32 added_ctxs;
 	unsigned int last_ctx;
 	u32 new_add_flags, new_drop_flags, new_slot_info;
+	struct xhci_virt_device *virt_dev;
 	int ret = 0;
 
 	ret = xhci_check_args(hcd, udev, ep, 1, true, __func__);
@@ -1425,11 +1426,25 @@
 		return 0;
 	}
 
-	in_ctx = xhci->devs[udev->slot_id]->in_ctx;
-	out_ctx = xhci->devs[udev->slot_id]->out_ctx;
+	virt_dev = xhci->devs[udev->slot_id];
+	in_ctx = virt_dev->in_ctx;
+	out_ctx = virt_dev->out_ctx;
 	ctrl_ctx = xhci_get_input_control_ctx(xhci, in_ctx);
 	ep_index = xhci_get_endpoint_index(&ep->desc);
 	ep_ctx = xhci_get_ep_ctx(xhci, out_ctx, ep_index);
+
+	/* If this endpoint is already in use, and the upper layers are trying
+	 * to add it again without dropping it, reject the addition.
+	 */
+	if (virt_dev->eps[ep_index].ring &&
+			!(le32_to_cpu(ctrl_ctx->drop_flags) &
+				xhci_get_endpoint_flag(&ep->desc))) {
+		xhci_warn(xhci, "Trying to add endpoint 0x%x "
+				"without dropping it.\n",
+				(unsigned int) ep->desc.bEndpointAddress);
+		return -EINVAL;
+	}
+
 	/* If the HCD has already noted the endpoint is enabled,
 	 * ignore this request.
 	 */
@@ -1445,8 +1460,7 @@
 	 * process context, not interrupt context (or so documenation
 	 * for usb_set_interface() and usb_set_configuration() claim).
 	 */
-	if (xhci_endpoint_init(xhci, xhci->devs[udev->slot_id],
-				udev, ep, GFP_NOIO) < 0) {
+	if (xhci_endpoint_init(xhci, virt_dev, udev, ep, GFP_NOIO) < 0) {
 		dev_dbg(&udev->dev, "%s - could not initialize ep %#x\n",
 				__func__, ep->desc.bEndpointAddress);
 		return -ENOMEM;