Prevented threading related crash in OpenGL module.

If the last shallow copy of a QImage which is cached in the
QGLTextureCache is destroyed in a thread at the same time as the
QGLContext which the texture was initialized in is active in a different
thread, the QImage thread incorrectly tries to make the context active
in two threads at once. To prevent this from happening it's best to
always do the texture clean-up in the main thread.

Task-number: QT-4238
Reviewed-by: Eskil Abrahamsen Blomfeldt

1 files changed, 6 insertions, 1 deletions

diff --git a/src/opengl/qgl.cpp b/src/opengl/qgl.cpp
index dbd295f..84cfa97 100644
--- a/src/opengl/qgl.cpp
+++ b/src/opengl/qgl.cpp
@@ -127,7 +127,12 @@ Q_GLOBAL_STATIC(QGLDefaultOverlayFormat, defaultOverlayFormatInstance)
 Q_GLOBAL_STATIC(QGLSignalProxy, theSignalProxy)
 QGLSignalProxy *QGLSignalProxy::instance()
 {
-    return theSignalProxy();
+    QGLSignalProxy *proxy = theSignalProxy();
+    if (proxy && proxy->thread() != qApp->thread()) {
+        if (proxy->thread() == QThread::currentThread())
+            proxy->moveToThread(qApp->thread());
+    }
+    return proxy;
 }