Possible Dead lock in the destructor of QObject

The problem was that we were locking a mutex that was global to thread
to remove posted events associated with a QObject from the posted event
list. We were also immediately deleting those events. If that triggers
the deletion of another QObject, you would then trigger a dead-lock.

Task-number: 259514
Reviewed-by: brad
Reviewed-by: ogoffart

1 files changed, 18 insertions, 0 deletions

diff --git a/tests/auto/qobject/tst_qobject.cpp b/tests/auto/qobject/tst_qobject.cpp
index 2823c71..bb00a0b 100644
--- a/tests/auto/qobject/tst_qobject.cpp
+++ b/tests/auto/qobject/tst_qobject.cpp
@@ -119,6 +119,7 @@ private slots:
     void qobjectConstCast();
     void uniqConnection();
     void interfaceIid();
+    void deleteQObjectWhenDeletingEvent();
 protected:
 };
 
@@ -2898,5 +2899,22 @@ void tst_QObject::interfaceIid()
              QByteArray());
 }
 
+void tst_QObject::deleteQObjectWhenDeletingEvent()
+{
+    //this is related to task 259514
+    //before the fix this used to dead lock when the QObject from the event was destroyed
+
+    struct MyEvent : public QEvent
+    {
+        MyEvent() : QEvent(QEvent::User) { }
+        QObject obj;
+    };
+
+    QObject o;
+    QApplication::postEvent(&o, new MyEvent);
+    QCoreApplication::removePostedEvents(&o); // here you would get a deadlock
+}
+
+
 QTEST_MAIN(tst_QObject)
 #include "tst_qobject.moc"