rtlwifi: rtl_usb: Fix for URB leaking when doing ifconfig up/down

In the function rtl_usb_start we pre-allocate a certain number of urbs
for RX path but they will not be freed when calling rtl_usb_stop. This
results in leaking urbs when doing ifconfig up and down. Eventually,
the system has no available urbs.
Signed-off-by: Michael Schenk <michael.schenk@albis-elcon.com>
Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Cc: Stable <stable@vger.kernel.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/realtek/rtlwifi/usb.c

@@ -818,12 +818,30 @@ static void rtl_usb_stop(struct ieee80211_hw *hw)
 	struct rtl_priv *rtlpriv = rtl_priv(hw);
 	struct rtl_hal *rtlhal = rtl_hal(rtl_priv(hw));
 	struct rtl_usb *rtlusb = rtl_usbdev(rtl_usbpriv(hw));
+	struct urb *urb;
 
 	/* should after adapter start and interrupt enable. */
 	set_hal_stop(rtlhal);
 	cancel_work_sync(&rtlpriv->works.fill_h2c_cmd);
 	/* Enable software */
 	SET_USB_STOP(rtlusb);
+
+	/* free pre-allocated URBs from rtl_usb_start() */
+	usb_kill_anchored_urbs(&rtlusb->rx_submitted);
+
+	tasklet_kill(&rtlusb->rx_work_tasklet);
+	cancel_work_sync(&rtlpriv->works.lps_change_work);
+
+	flush_workqueue(rtlpriv->works.rtl_wq);
+
+	skb_queue_purge(&rtlusb->rx_queue);
+
+	while ((urb = usb_get_from_anchor(&rtlusb->rx_cleanup_urbs))) {
+		usb_free_coherent(urb->dev, urb->transfer_buffer_length,
+				urb->transfer_buffer, urb->transfer_dma);
+		usb_free_urb(urb);
+	}
+
 	rtlpriv->cfg->ops->hw_disable(hw);
 }