vnc: make sure we finish disconnect

It may happen that vnc connections linger in disconnecting state forever
because VncState happens to be in a state where vnc_update_client()
exists early and never reaches the vnc_disconnect_finish() call at the
bottom of the function.  Fix that by doing an additinal check at the
start of the function.

https://bugzilla.redhat.com/show_bug.cgi?id=1352799

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Message-id: 1468405280-2571-1-git-send-email-kraxel@redhat.com

ui/vnc.c

@@ -1024,6 +1024,11 @@ static int find_and_clear_dirty_height(VncState *vs,
 
 static int vnc_update_client(VncState *vs, int has_dirty, bool sync)
 {
+    if (vs->disconnecting) {
+        vnc_disconnect_finish(vs);
+        return 0;
+    }
+
     vs->has_dirty += has_dirty;
     if (vs->need_update && !vs->disconnecting) {
         VncDisplay *vd = vs->vd;