adaptivedemux: do not erase data while updates-loop is running

Make sure the manifest update loop is stopped before proceeding with the
resetting of the manifest data. Otherwise, the updates loop will try to
use it and it leads to a segfault

https://bugzilla.gnome.org/show_bug.cgi?id=783028

gst-libs/gst/adaptivedemux/gstadaptivedemux.c

@@ -283,7 +283,8 @@ static void gst_adaptive_demux_start_manifest_update_task (GstAdaptiveDemux *
 
 static void gst_adaptive_demux_start_tasks (GstAdaptiveDemux * demux,
     gboolean start_preroll_streams);
-static void gst_adaptive_demux_stop_tasks (GstAdaptiveDemux * demux);
+static void gst_adaptive_demux_stop_tasks (GstAdaptiveDemux * demux,
+    gboolean stop_updates);
 static GstFlowReturn gst_adaptive_demux_combine_flows (GstAdaptiveDemux *
     demux);
 static void
@@ -561,13 +562,7 @@ gst_adaptive_demux_change_state (GstElement * element,
       GST_MANIFEST_LOCK (demux);
       demux->running = FALSE;
       gst_adaptive_demux_reset (demux);
-      gst_adaptive_demux_stop_manifest_update_task (demux);
       GST_MANIFEST_UNLOCK (demux);
-
-      /* demux->priv->updates_task value never changes, so it is safe to read it
-       * outside critical section
-       */
-      gst_task_join (demux->priv->updates_task);
       break;
     case GST_STATE_CHANGE_READY_TO_PAUSED:
       GST_MANIFEST_LOCK (demux);
@@ -774,7 +769,7 @@ gst_adaptive_demux_reset (GstAdaptiveDemux * demux)
   old_streams = demux->priv->old_streams;
   demux->priv->old_streams = NULL;
 
-  gst_adaptive_demux_stop_tasks (demux);
+  gst_adaptive_demux_stop_tasks (demux, TRUE);
 
   if (klass->reset)
     klass->reset (demux);
@@ -1577,11 +1572,11 @@ gst_adaptive_demux_handle_seek_event (GstAdaptiveDemux * demux, GstPad * pad,
     gst_adaptive_demux_push_src_event (demux, fevent);
     GST_MANIFEST_LOCK (demux);
 
-    gst_adaptive_demux_stop_tasks (demux);
+    gst_adaptive_demux_stop_tasks (demux, FALSE);
   } else if ((rate > 0 && start_type != GST_SEEK_TYPE_NONE) ||
       (rate < 0 && stop_type != GST_SEEK_TYPE_NONE)) {
 
-    gst_adaptive_demux_stop_tasks (demux);
+    gst_adaptive_demux_stop_tasks (demux, FALSE);
   }
 
   GST_ADAPTIVE_DEMUX_SEGMENT_LOCK (demux);
@@ -1961,12 +1956,14 @@ gst_adaptive_demux_start_manifest_update_task (GstAdaptiveDemux * demux)
  * the demux element.
  */
 static void
-gst_adaptive_demux_stop_tasks (GstAdaptiveDemux * demux)
+gst_adaptive_demux_stop_tasks (GstAdaptiveDemux * demux, gboolean stop_updates)
 {
   GList *iter;
 
   GST_LOG_OBJECT (demux, "Stopping tasks");
 
+  if (stop_updates)
+    gst_adaptive_demux_stop_manifest_update_task (demux);
   for (iter = demux->streams; iter; iter = g_list_next (iter)) {
     GstAdaptiveDemuxStream *stream = iter->data;
 
@@ -2010,6 +2007,8 @@ gst_adaptive_demux_stop_tasks (GstAdaptiveDemux * demux)
   }
 
   GST_MANIFEST_UNLOCK (demux);
+  if (stop_updates)
+    gst_task_join (demux->priv->updates_task);
 
   GST_MANIFEST_LOCK (demux);