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rtpssrcdemux: Avoid taking streamlock out-of-band
In this change we now protect the internal srcpads list using the stream lock and limit usage of the internal stream lock to preventing data flowing on the other src pad type while creating and signalling the new pad. This fixes a deadlock with RTPBin shutdown lock. These two locks would end up being taken in two different order, which caused a deadlock. More generally, we should not rely on a streamlock when handling out-of-band data, so as a side effect, we should not take a stream lock when iterating internal links.
This commit is contained in:
Nicolas Dufresne
parent
a493bcd549
commit
f7c712d0b8
2 changed files with 125 additions and 38 deletions
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@ -145,6 +145,7 @@ struct _GstRtpSsrcDemuxPad
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};
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/* find a src pad for a given SSRC, returns NULL if the SSRC was not found
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* MUST be called with object lock
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*/
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static GstRtpSsrcDemuxPad *
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find_demux_pad_for_ssrc (GstRtpSsrcDemux * demux, guint32 ssrc)
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@ -160,6 +161,38 @@ find_demux_pad_for_ssrc (GstRtpSsrcDemux * demux, guint32 ssrc)
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return NULL;
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}
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/* returns a reference to the pad if found, %NULL otherwise */
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static GstPad *
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get_demux_pad_for_ssrc (GstRtpSsrcDemux * demux, guint32 ssrc, PadType padtype)
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{
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GstRtpSsrcDemuxPad *demuxpad;
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GstPad *retpad;
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GST_OBJECT_LOCK (demux);
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demuxpad = find_demux_pad_for_ssrc (demux, ssrc);
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if (!demuxpad) {
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GST_OBJECT_UNLOCK (demux);
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return NULL;
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}
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switch (padtype) {
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case RTP_PAD:
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retpad = gst_object_ref (demuxpad->rtp_pad);
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break;
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case RTCP_PAD:
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retpad = gst_object_ref (demuxpad->rtcp_pad);
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break;
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default:
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retpad = NULL;
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g_assert_not_reached ();
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}
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GST_OBJECT_UNLOCK (demux);
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return retpad;
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}
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static GstEvent *
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add_ssrc_and_ref (GstEvent * event, guint32 ssrc)
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{
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@ -229,6 +262,7 @@ forward_initial_events (GstRtpSsrcDemux * demux, guint32 ssrc, GstPad * pad,
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gst_pad_sticky_events_foreach (sinkpad, forward_sticky_events, &fdata);
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}
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/* MUST only be called from streaming thread */
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static GstPad *
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find_or_create_demux_pad_for_ssrc (GstRtpSsrcDemux * demux, guint32 ssrc,
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PadType padtype)
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@ -242,22 +276,9 @@ find_or_create_demux_pad_for_ssrc (GstRtpSsrcDemux * demux, guint32 ssrc,
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INTERNAL_STREAM_LOCK (demux);
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demuxpad = find_demux_pad_for_ssrc (demux, ssrc);
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if (demuxpad != NULL) {
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switch (padtype) {
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case RTP_PAD:
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retpad = gst_object_ref (demuxpad->rtp_pad);
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break;
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case RTCP_PAD:
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retpad = gst_object_ref (demuxpad->rtcp_pad);
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break;
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default:
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retpad = NULL;
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g_assert_not_reached ();
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}
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retpad = get_demux_pad_for_ssrc (demux, ssrc, padtype);
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if (retpad != NULL) {
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INTERNAL_STREAM_UNLOCK (demux);
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return retpad;
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}
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@ -283,7 +304,9 @@ find_or_create_demux_pad_for_ssrc (GstRtpSsrcDemux * demux, guint32 ssrc,
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gst_pad_set_element_private (rtp_pad, demuxpad);
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gst_pad_set_element_private (rtcp_pad, demuxpad);
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GST_OBJECT_LOCK (demux);
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demux->srcpads = g_slist_prepend (demux->srcpads, demuxpad);
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GST_OBJECT_UNLOCK (demux);
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gst_pad_set_query_function (rtp_pad, gst_rtp_ssrc_demux_src_query);
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gst_pad_set_iterate_internal_links_function (rtp_pad,
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@ -316,17 +339,11 @@ find_or_create_demux_pad_for_ssrc (GstRtpSsrcDemux * demux, guint32 ssrc,
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g_assert_not_reached ();
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}
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gst_object_ref (rtp_pad);
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gst_object_ref (rtcp_pad);
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g_signal_emit (G_OBJECT (demux),
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gst_rtp_ssrc_demux_signals[SIGNAL_NEW_SSRC_PAD], 0, ssrc, rtp_pad);
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INTERNAL_STREAM_UNLOCK (demux);
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gst_object_unref (rtp_pad);
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gst_object_unref (rtcp_pad);
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return retpad;
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}
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@ -486,17 +503,17 @@ gst_rtp_ssrc_demux_clear_ssrc (GstRtpSsrcDemux * demux, guint32 ssrc)
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{
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GstRtpSsrcDemuxPad *dpad;
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INTERNAL_STREAM_LOCK (demux);
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GST_OBJECT_LOCK (demux);
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dpad = find_demux_pad_for_ssrc (demux, ssrc);
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if (dpad == NULL) {
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INTERNAL_STREAM_UNLOCK (demux);
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GST_OBJECT_UNLOCK (demux);
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goto unknown_pad;
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}
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GST_DEBUG_OBJECT (demux, "clearing pad for SSRC %08x", ssrc);
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demux->srcpads = g_slist_remove (demux->srcpads, dpad);
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INTERNAL_STREAM_UNLOCK (demux);
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GST_OBJECT_UNLOCK (demux);
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gst_pad_set_active (dpad->rtp_pad, FALSE);
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gst_pad_set_active (dpad->rtcp_pad, FALSE);
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@ -535,7 +552,7 @@ forward_event (GstPad * pad, gpointer user_data)
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GSList *walk = NULL;
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GstEvent *newevent = NULL;
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INTERNAL_STREAM_LOCK (fdata->demux);
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GST_OBJECT_LOCK (fdata->demux);
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for (walk = fdata->demux->srcpads; walk; walk = walk->next) {
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GstRtpSsrcDemuxPad *dpad = (GstRtpSsrcDemuxPad *) walk->data;
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@ -544,7 +561,7 @@ forward_event (GstPad * pad, gpointer user_data)
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break;
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}
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}
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INTERNAL_STREAM_UNLOCK (fdata->demux);
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GST_OBJECT_UNLOCK (fdata->demux);
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if (newevent)
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fdata->res &= gst_pad_push_event (pad, newevent);
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@ -582,7 +599,6 @@ gst_rtp_ssrc_demux_chain (GstPad * pad, GstObject * parent, GstBuffer * buf)
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guint32 ssrc;
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GstRTPBuffer rtp = { NULL };
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GstPad *srcpad;
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GstRtpSsrcDemuxPad *dpad;
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demux = GST_RTP_SSRC_DEMUX (parent);
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@ -602,14 +618,17 @@ gst_rtp_ssrc_demux_chain (GstPad * pad, GstObject * parent, GstBuffer * buf)
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ret = gst_pad_push (srcpad, buf);
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if (ret != GST_FLOW_OK) {
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GstPad *active_pad;
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/* check if the ssrc still there, may have been removed */
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INTERNAL_STREAM_LOCK (demux);
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dpad = find_demux_pad_for_ssrc (demux, ssrc);
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if (dpad == NULL || dpad->rtp_pad != srcpad) {
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active_pad = get_demux_pad_for_ssrc (demux, ssrc, RTP_PAD);
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if (active_pad == NULL || active_pad != srcpad) {
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/* SSRC was removed during the push ... ignore the error */
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ret = GST_FLOW_OK;
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}
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INTERNAL_STREAM_UNLOCK (demux);
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g_clear_object (&active_pad);
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}
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gst_object_unref (srcpad);
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@ -644,7 +663,6 @@ gst_rtp_ssrc_demux_rtcp_chain (GstPad * pad, GstObject * parent,
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GstRTCPPacket packet;
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GstRTCPBuffer rtcp = { NULL, };
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GstPad *srcpad;
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GstRtpSsrcDemuxPad *dpad;
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demux = GST_RTP_SSRC_DEMUX (parent);
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@ -689,14 +707,16 @@ gst_rtp_ssrc_demux_rtcp_chain (GstPad * pad, GstObject * parent,
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ret = gst_pad_push (srcpad, buf);
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if (ret != GST_FLOW_OK) {
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GstPad *active_pad;
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/* check if the ssrc still there, may have been removed */
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INTERNAL_STREAM_LOCK (demux);
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dpad = find_demux_pad_for_ssrc (demux, ssrc);
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if (dpad == NULL || dpad->rtcp_pad != srcpad) {
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active_pad = get_demux_pad_for_ssrc (demux, ssrc, RTCP_PAD);
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if (active_pad == NULL || active_pad != srcpad) {
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/* SSRC was removed during the push ... ignore the error */
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ret = GST_FLOW_OK;
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}
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INTERNAL_STREAM_UNLOCK (demux);
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g_clear_object (&active_pad);
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}
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gst_object_unref (srcpad);
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@ -786,7 +806,7 @@ gst_rtp_ssrc_demux_iterate_internal_links_src (GstPad * pad, GstObject * parent)
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demux = GST_RTP_SSRC_DEMUX (parent);
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INTERNAL_STREAM_LOCK (demux);
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GST_OBJECT_LOCK (demux);
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for (current = demux->srcpads; current; current = g_slist_next (current)) {
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GstRtpSsrcDemuxPad *dpad = (GstRtpSsrcDemuxPad *) current->data;
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@ -807,7 +827,7 @@ gst_rtp_ssrc_demux_iterate_internal_links_src (GstPad * pad, GstObject * parent)
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g_value_unset (&val);
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}
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INTERNAL_STREAM_UNLOCK (demux);
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GST_OBJECT_UNLOCK (demux);
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return it;
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}
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@ -174,6 +174,72 @@ GST_START_TEST (test_event_forwarding)
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GST_END_TEST;
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typedef struct
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{
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gint ready;
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GMutex mutex;
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GCond cond;
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} LockTestContext;
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static void
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new_ssrc_pad_cb (GstElement * element, guint ssrc, GstPad * pad,
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LockTestContext * ctx)
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{
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g_message ("Signalling ready");
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g_atomic_int_set (&ctx->ready, 1);
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g_message ("Waiting no more ready");
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while (g_atomic_int_get (&ctx->ready))
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g_usleep (G_USEC_PER_SEC / 100);
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g_mutex_lock (&ctx->mutex);
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g_mutex_unlock (&ctx->mutex);
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}
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static gpointer
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push_buffer_func (gpointer user_data)
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{
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GstHarness *h = user_data;
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gst_harness_push (h, create_buffer (0, 0xdeadbeef));
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return NULL;
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}
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GST_START_TEST (test_oob_event_locking)
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{
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GstHarness *h = gst_harness_new_with_padnames ("rtpssrcdemux", "sink", NULL);
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LockTestContext ctx = { FALSE, };
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GThread *thread;
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g_mutex_init (&ctx.mutex);
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g_cond_init (&ctx.cond);
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gst_harness_set_src_caps_str (h, "application/x-rtp");
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g_signal_connect (h->element,
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"new-ssrc-pad", G_CALLBACK (new_ssrc_pad_cb), &ctx);
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thread = g_thread_new ("streaming-thread", push_buffer_func, h);
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g_mutex_lock (&ctx.mutex);
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g_message ("Waiting for ready");
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while (!g_atomic_int_get (&ctx.ready))
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g_usleep (G_USEC_PER_SEC / 100);
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g_message ("Signal no more ready");
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g_atomic_int_set (&ctx.ready, 0);
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gst_harness_push_event (h,
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gst_event_new_custom (GST_EVENT_CUSTOM_DOWNSTREAM_OOB, NULL));
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g_mutex_unlock (&ctx.mutex);
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g_thread_join (thread);
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g_mutex_clear (&ctx.mutex);
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g_cond_clear (&ctx.cond);
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gst_harness_teardown (h);
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}
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GST_END_TEST;
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static Suite *
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rtpssrcdemux_suite (void)
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{
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@ -182,6 +248,7 @@ rtpssrcdemux_suite (void)
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suite_add_tcase (s, tc_chain);
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tcase_add_test (tc_chain, test_event_forwarding);
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tcase_add_test (tc_chain, test_oob_event_locking);
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return s;
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}
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