staging: usbip: bugfixes related to kthread conversion

commit d2dd0b07 upstream.

When doing a usb port reset do a queued reset instead to prevent a
deadlock: the reset will cause the driver to unbind, causing the
usb_driver_lock_for_reset to stall.
Signed-off-by: Arjan Mels <arjan.mels@gmx.net>
Cc: Takahiro Hirofuchi <hirofuchi@users.sourceforge.net>
Cc: Max Vozeler <max@vozeler.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/usbip/stub_rx.c

@@ -168,33 +168,23 @@ static int tweak_set_configuration_cmd(struct urb *urb)
 
 static int tweak_reset_device_cmd(struct urb *urb)
 {
-	struct usb_ctrlrequest *req;
-	__u16 value;
-	__u16 index;
-	int ret;
-
-	req = (struct usb_ctrlrequest *) urb->setup_packet;
-	value = le16_to_cpu(req->wValue);
-	index = le16_to_cpu(req->wIndex);
-
-	usbip_uinfo("reset_device (port %d) to %s\n", index,
-						dev_name(&urb->dev->dev));
+	struct stub_priv *priv = (struct stub_priv *) urb->context;
+	struct stub_device *sdev = priv->sdev;
 
-	/* all interfaces should be owned by usbip driver, so just reset it.  */
-	ret = usb_lock_device_for_reset(urb->dev, NULL);
-	if (ret < 0) {
-		dev_err(&urb->dev->dev, "lock for reset\n");
-		return ret;
-	}
-
-	/* try to reset the device */
-	ret = usb_reset_device(urb->dev);
-	if (ret < 0)
-		dev_err(&urb->dev->dev, "device reset\n");
+	usbip_uinfo("reset_device %s\n", dev_name(&urb->dev->dev));
 
-	usb_unlock_device(urb->dev);
-
-	return ret;
+	/*
+	 * usb_lock_device_for_reset caused a deadlock: it causes the driver
+	 * to unbind. In the shutdown the rx thread is signalled to shut down
+	 * but this thread is pending in the usb_lock_device_for_reset.
+	 *
+	 * Instead queue the reset.
+	 *
+	 * Unfortunatly an existing usbip connection will be dropped due to
+	 * driver unbinding.
+	 */
+	usb_queue_reset_device(sdev->interface);
+	return 0;
 }
 
 /*