QThread: fix race when setting the eventDispatcher

Use QMutexLocker to make this thread-safe.

Task-number: QTBUG-29452
(cherry picked and adapted from qtbase/f4609b202208fe592d24c7ae3b4a48ee83045497)
Change-Id: I5caf71d9a5dc6e3d655eac84426a0c5592772235
Reviewed-by: Louai Al-Khanji <louai.al-khanji@theqtcompany.com>

3 files changed, 7 insertions, 0 deletions

diff --git a/src/corelib/thread/qthread_symbian.cpp b/src/corelib/thread/qthread_symbian.cpp
index 1d3376ef38..607e3ac10b 100644
--- a/src/corelib/thread/qthread_symbian.cpp
+++ b/src/corelib/thread/qthread_symbian.cpp
@@ -336,7 +336,9 @@ typedef void*(*QtThreadCallback)(void*);
 
 void QThreadPrivate::createEventDispatcher(QThreadData *data)
 {
+    QMutexLocker l(&data->postEventList.mutex);
     data->eventDispatcher = new QEventDispatcherSymbian;
+    l.unlock();
     data->eventDispatcher->startingUp();
 }
 
diff --git a/src/corelib/thread/qthread_unix.cpp b/src/corelib/thread/qthread_unix.cpp
index 4d85968ceb..7d8df26356 100644
--- a/src/corelib/thread/qthread_unix.cpp
+++ b/src/corelib/thread/qthread_unix.cpp
@@ -273,6 +273,8 @@ typedef void*(*QtThreadCallback)(void*);
 
 void QThreadPrivate::createEventDispatcher(QThreadData *data)
 {
+    QMutexLocker l(&data->postEventList.mutex);
+
 #if defined(Q_OS_BLACKBERRY)
     data->eventDispatcher = new QEventDispatcherBlackberry;
 #else
@@ -286,6 +288,7 @@ void QThreadPrivate::createEventDispatcher(QThreadData *data)
     data->eventDispatcher = new QEventDispatcherUNIX;
 #endif
 
+    l.unlock();
     data->eventDispatcher->startingUp();
 }
 
diff --git a/src/corelib/thread/qthread_win.cpp b/src/corelib/thread/qthread_win.cpp
index 4ebae9ec24..01ddf02c26 100644
--- a/src/corelib/thread/qthread_win.cpp
+++ b/src/corelib/thread/qthread_win.cpp
@@ -318,7 +318,9 @@ void qt_set_thread_name(HANDLE threadId, LPCSTR threadName)
 
 void QThreadPrivate::createEventDispatcher(QThreadData *data)
 {
+    QMutexLocker l(&data->postEventList.mutex);
     data->eventDispatcher = new QEventDispatcherWin32;
+    l.unlock();
     data->eventDispatcher->startingUp();
 }