[rhythmbox] xfade: fix race in buffering handling

[Jonathan Matthew <jmatthew src gnome org>]

commit 96e1f98300941201ecfbe69b7f18c6c98cad4930
Author: Jonathan Matthew <jonathan d14n org>
Date:   Tue Apr 25 19:16:43 2017 +1000

    xfade: fix race in buffering handling
    
    If a stream starts buffering, then finishes before the probe used to
    unlink it fires, remove the probe and continue on.  Improves streaming
    from http servers.

 backends/gstreamer/rb-player-gst-xfade.c |    9 +++++++++
 1 files changed, 9 insertions(+), 0 deletions(-)
---
diff --git a/backends/gstreamer/rb-player-gst-xfade.c b/backends/gstreamer/rb-player-gst-xfade.c
index 3093905..cac4edf 100644
--- a/backends/gstreamer/rb-player-gst-xfade.c
+++ b/backends/gstreamer/rb-player-gst-xfade.c
@@ -1898,6 +1898,15 @@ rb_player_gst_xfade_bus_cb (GstBus *bus, GstMessage *message, RBPlayerGstXFade *
                                break;
 
                        default:
+                               /* make sure we're not going to remove it */
+                               g_mutex_lock (&stream->lock);
+                               if (stream->block_probe_id != 0) {
+                                       gst_pad_remove_probe (stream->src_pad, stream->block_probe_id);
+                                       stream->block_probe_id = 0;
+                                       stream->needs_unlink = FALSE;
+                               }
+                               g_mutex_unlock (&stream->lock);
+
                                rb_debug ("stream %s is buffered, resuming", stream->uri);
                                link_and_unblock_stream (stream, &error);
                                if (error) {