try to setup a pipeline of which the source is alsasrc.
when set pipeline state to playing, the alsasrc device is not ready and we got a resource error, the state change failed.
after this the state of audiosrcringbuffer is GST_AUDIO_RING_BUFFER_STATE_ERROR.
then we set pipeline state to null and try to set the pipeline state to play again, this time the alsa src device is ready and open is success. but we still get an internal flow error as the ring buffer is not created again, the state is still GST_AUDIO_RING_BUFFER_STATE_ERROR.
simply use following modification to help understanding this problem:
===========================code===============================
static GstStateChangeReturn
gst_audio_base_src_change_state (GstElement * element,
    GstStateChange transition)
{
  GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS;
  GstAudioBaseSrc *src = GST_AUDIO_BASE_SRC (element);

  switch (transition) {
    case GST_STATE_CHANGE_NULL_TO_READY:
      GST_DEBUG_OBJECT (src, "NULL->READY");
      GST_OBJECT_LOCK (src);
+     if (src->ringbuffer != NULL) {
+       gst_object_unparent (GST_OBJECT_CAST (src->ringbuffer));
+       src->ringbuffer = NULL;
+     }
      if (src->ringbuffer == NULL) {
        gst_audio_clock_reset (GST_AUDIO_CLOCK (src->clock), 0);
        src->ringbuffer = gst_audio_base_src_create_ringbuffer (src);
      }