[gst-devel] Possible race-condition when using g_enum_register_static

[Michal Benes]

Hi everybody,

	my transcoding pipeline for one video stream and two audio streams
(both decoded by mad plugin) has produced the following warning

GLib-GObject-WARNING **: cannot register existing type
 `GstMadEmphasis'

two times and crashed short afterwards. This behavior is not
reproducible. During code review I have found the following code in
gstmad.c

gst_mad_emphasis_get_type (void)
{
  static GType mad_emphasis_type = 0;
  static GEnumValue mad_emphasis[] = <value omitted>;

  if (!mad_emphasis_type) {
    mad_emphasis_type = g_enum_register_static ("GstMadEmphasis",
mad_emphasis);
  }
  return mad_emphasis_type;
}

	Isn't this racy when two mad plugins in two separate threads call this
function for the first time? They clearly share the mad_emphasis_type
variable. 

	The problem is that the code like this is quite common in GStreamer.

	Am I wrong or is this a real problem?

		Michal