Merge remote-tracking branch 'origin/5.15' into dev

 Conflicts:
	src/corelib/tools/qhash.h
	src/gui/kernel/qevent.h
	src/widgets/kernel/qshortcut.cpp
	src/widgets/kernel/qshortcut.h

Change-Id: If61c206ee43ad1d97f5b07f58ac93c4583ce5620

1 files changed, 7 insertions, 2 deletions

diff --git a/src/corelib/kernel/qobject_p.h b/src/corelib/kernel/qobject_p.h
index db62c03b7a..a421b55764 100644
--- a/src/corelib/kernel/qobject_p.h
+++ b/src/corelib/kernel/qobject_p.h
@@ -362,8 +362,13 @@ public:
     }
 public:
     ExtraData *extraData;    // extra data set by the user
-    QThreadData *getThreadData() const { return threadData; }
-    QThreadData *threadData; // id of the thread that owns the object
+    QThreadData *getThreadData() const { return threadData.loadAcquire(); }
+    // This atomic requires acquire/release semantics in a few places,
+    // e.g. QObject::moveToThread must synchronize with QCoreApplication::postEvent,
+    // because postEvent is thread-safe.
+    // However, most of the code paths involving QObject are only reentrant and
+    // not thread-safe, so synchronization should not be necessary there.
+    QAtomicPointer<QThreadData> threadData; // id of the thread that owns the object
 
     using ConnectionDataPointer = QExplicitlySharedDataPointer<ConnectionData>;
     QAtomicPointer<ConnectionData> connections;