Fix a race where QThread::exit() is "lost" when called after start()

This reverts commit 9aa4538b219ed759a47e8d1f93c2797bf07b5e2f and fixes
the bug in a different way. If the QThreadData::quitNow flag is set when
entering QThread::exec(), allow QEventLoop::exec() to bail out and reset
quitNow after QEventLoop::exec() has returned (not before).

Task-number: QTBUG-1184
Reviewed-by: olivier

4 files changed, 6 insertions, 38 deletions

diff --git a/src/corelib/thread/qthread.cpp b/src/corelib/thread/qthread.cpp
index c35eb28..cdcb65c 100644
--- a/src/corelib/thread/qthread.cpp
+++ b/src/corelib/thread/qthread.cpp
@@ -174,7 +174,7 @@ void QAdoptedThread::run()
 
 QThreadPrivate::QThreadPrivate(QThreadData *d)
     : QObjectPrivate(), running(false), finished(false), terminated(false),
-      stackSize(0), priority(QThread::InheritPriority), data(d), object(0)
+      stackSize(0), priority(QThread::InheritPriority), data(d)
 {
 #if defined (Q_OS_UNIX)
     thread_id = 0;
@@ -377,9 +377,6 @@ QThread::QThread(QObject *parent)
     Q_D(QThread);
     // fprintf(stderr, "QThreadData %p created for thread %p\n", d->data, this);
     d->data->thread = this;
-
-    d->object = new QThreadPrivateInternalObject;
-    d->object->moveToThread(this);
 }
 
 /*! \internal
@@ -390,8 +387,6 @@ QThread::QThread(QThreadPrivate &dd, QObject *parent)
     Q_D(QThread);
     // fprintf(stderr, "QThreadData %p taken from private data for thread %p\n", d->data, this);
     d->data->thread = this;
-
-    // do not create the internal object for adopted threads
 }
 
 /*!
@@ -413,9 +408,6 @@ QThread::~QThread()
 
         d->data->thread = 0;
     }
-
-    delete d->object;
-    d->object = 0;
 }
 
 /*!
@@ -488,11 +480,11 @@ uint QThread::stackSize() const
 int QThread::exec()
 {
     Q_D(QThread);
-    QMutexLocker locker(&d->mutex);
-    d->data->quitNow = false;
     QEventLoop eventLoop;
-    locker.unlock();
     int returnCode = eventLoop.exec();
+
+    QMutexLocker locker(&d->mutex);
+    d->data->quitNow = false;
     return returnCode;
 }
 
@@ -518,21 +510,6 @@ int QThread::exec()
 void QThread::exit(int returnCode)
 {
     Q_D(QThread);
-    if (d->object) {
-        QMetaObject::invokeMethod(d->object, "exit", Q_ARG(int, returnCode));
-    } else {
-        QMutexLocker locker(&d->mutex);
-        d->data->quitNow = true;
-        for (int i = 0; i < d->data->eventLoops.size(); ++i) {
-            QEventLoop *eventLoop = d->data->eventLoops.at(i);
-            eventLoop->exit(returnCode);
-        }
-    }
-}
-
-void QThreadPrivateInternalObject::exit(int returnCode)
-{
-    QThreadPrivate *d = static_cast<QThreadPrivate *>(QObjectPrivate::get(thread()));
     QMutexLocker locker(&d->mutex);
     d->data->quitNow = true;
     for (int i = 0; i < d->data->eventLoops.size(); ++i) {
diff --git a/src/corelib/thread/qthread_p.h b/src/corelib/thread/qthread_p.h
index 54ffd80..44eb8f8 100644
--- a/src/corelib/thread/qthread_p.h
+++ b/src/corelib/thread/qthread_p.h
@@ -113,14 +113,6 @@ public:
 
 #ifndef QT_NO_THREAD
 
-class QThreadPrivateInternalObject : public QObject
-{
-    Q_OBJECT
-
-public slots:
-    void exit(int);
-};
-
 class QThreadPrivate : public QObjectPrivate
 {
     Q_DECLARE_PUBLIC(QThread)
@@ -165,7 +157,6 @@ public:
     bool terminationEnabled, terminatePending;
 # endif
     QThreadData *data;
-    QThreadPrivateInternalObject *object;
 
     static void createEventDispatcher(QThreadData *data);
 };
diff --git a/src/corelib/thread/qthread_unix.cpp b/src/corelib/thread/qthread_unix.cpp
index 6b34b5f..bd31d9c 100644
--- a/src/corelib/thread/qthread_unix.cpp
+++ b/src/corelib/thread/qthread_unix.cpp
@@ -253,7 +253,6 @@ void *QThreadPrivate::start(void *arg)
     pthread_setspecific(current_thread_data_key, data);
 
     data->ref();
-    data->quitNow = false;
 
     // ### TODO: allow the user to create a custom event dispatcher
     createEventDispatcher(data);
@@ -495,6 +494,7 @@ void QThread::start(Priority priority)
     d->running = true;
     d->finished = false;
     d->terminated = false;
+    d->data->quitNow = false;
 
     pthread_attr_t attr;
     pthread_attr_init(&attr);
diff --git a/src/corelib/thread/qthread_win.cpp b/src/corelib/thread/qthread_win.cpp
index 37d5b87..9826dcb 100644
--- a/src/corelib/thread/qthread_win.cpp
+++ b/src/corelib/thread/qthread_win.cpp
@@ -298,7 +298,6 @@ unsigned int __stdcall QThreadPrivate::start(void *arg)
 
     QThread::setTerminationEnabled(false);
 
-    data->quitNow = false;
     // ### TODO: allow the user to create a custom event dispatcher
     createEventDispatcher(data);
 
@@ -405,6 +404,7 @@ void QThread::start(Priority priority)
     d->running = true;
     d->finished = false;
     d->terminated = false;
+    d->data->quitNow = false;
 
     /*
       NOTE: we create the thread in the suspended state, set the