The code in gstswitch.c appears to have a locking order of OBJECT_LOCK, SWITCH_LOCK. This is bogus. Although the code attempts to get this right, there are still some errors like in the release_request_pad function:

  GST_OBJECT_LOCK (gstswitch);
  gstswitch->nb_sinkpads--;
  GST_SWITCH_LOCK (gstswitch);
  if (gstswitch->active_sinkpad == pad) {
    gst_object_unref (gstswitch->active_sinkpad);
    gstswitch->active_sinkpad = NULL;
    if (gstswitch->nb_sinkpads == 0) {
      GstIterator *iter =
          gst_element_iterate_sink_pads (GST_ELEMENT (gstswitch));
      gpointer active_sinkpad_store = (gpointer) gstswitch->active_sinkpad;

The proper solution is to make the locking order SWITCH_LOCK, OBJECT_LOCK.