[rygel] engine-gst: Guard read access to critical section

[Jens Georg <jensgeorg src gnome org>]

commit b3066f39d1ea93f836f6aa6d2640c6560726f07e
Author: Debarshi Ray <debarshir gnome org>
Date:   Tue Sep 9 11:56:47 2014 +0200

    engine-gst: Guard read access to critical section
    
    https://bugzilla.gnome.org/show_bug.cgi?id=734358

 src/media-engines/gstreamer/rygel-gst-sink.vala |    8 ++++----
 1 files changed, 4 insertions(+), 4 deletions(-)
---
diff --git a/src/media-engines/gstreamer/rygel-gst-sink.vala b/src/media-engines/gstreamer/rygel-gst-sink.vala
index acdaefe..9620a5c 100644
--- a/src/media-engines/gstreamer/rygel-gst-sink.vala
+++ b/src/media-engines/gstreamer/rygel-gst-sink.vala
@@ -78,12 +78,12 @@ internal class Rygel.GstSink : Sink {
     }
 
     public void freeze () {
-        if (this.frozen) {
-            return;
+        this.buffer_mutex.lock ();
+
+        if (!this.frozen) {
+            this.frozen = true;
         }
 
-        this.buffer_mutex.lock ();
-        this.frozen = true;
         this.buffer_mutex.unlock ();
     }