Moved all XCB event handling back into the main thread.

There are to many synchronization problems if any GL call can lead the
event processing thread to stall.

6 files changed, 86 insertions, 210 deletions

diff --git a/src/plugins/platforms/xcb/qglxintegration.cpp b/src/plugins/platforms/xcb/qglxintegration.cpp
index d1171b8..19a9503 100644
--- a/src/plugins/platforms/xcb/qglxintegration.cpp
+++ b/src/plugins/platforms/xcb/qglxintegration.cpp
@@ -137,7 +137,6 @@ void QGLXContext::createDefaultSharedContext(QXcbScreen *screen)
 void QGLXContext::makeCurrent()
 {
     Q_XCB_NOOP(m_screen->connection());
-    m_screen->connection()->setEventProcessingEnabled(false);
     QPlatformGLContext::makeCurrent();
     glXMakeCurrent(DISPLAY_FROM_XCB(m_screen), m_drawable, m_context);
     Q_XCB_NOOP(m_screen->connection());
@@ -148,7 +147,6 @@ void QGLXContext::doneCurrent()
     Q_XCB_NOOP(m_screen->connection());
     QPlatformGLContext::doneCurrent();
     glXMakeCurrent(DISPLAY_FROM_XCB(m_screen), 0, 0);
-    m_screen->connection()->setEventProcessingEnabled(true);
     Q_XCB_NOOP(m_screen->connection());
 }
 
diff --git a/src/plugins/platforms/xcb/qxcbconnection.cpp b/src/plugins/platforms/xcb/qxcbconnection.cpp
index 05d3440..ec1fc1b 100644
--- a/src/plugins/platforms/xcb/qxcbconnection.cpp
+++ b/src/plugins/platforms/xcb/qxcbconnection.cpp
@@ -47,6 +47,7 @@
 #include <QtAlgorithms>
 #include <QSocketNotifier>
 #include <QtGui/private/qapplication_p.h>
+#include <QAbstractEventDispatcher>
 
 #include <QtCore/QDebug>
 
@@ -76,8 +77,6 @@ extern "C" {
 
 QXcbConnection::QXcbConnection(const char *displayName)
     : m_displayName(displayName ? QByteArray(displayName) : qgetenv("DISPLAY"))
-    , m_pauseId(0)
-    , m_enabled(true)
 #ifdef XCB_USE_DRI2
     , m_dri2_major(0)
     , m_dri2_minor(0)
@@ -114,12 +113,6 @@ QXcbConnection::QXcbConnection(const char *displayName)
         xcb_screen_next(&it);
     }
 
-    m_connectionEventListener = xcb_generate_id(xcb_connection());
-    xcb_create_window(xcb_connection(), XCB_COPY_FROM_PARENT,
-                      m_connectionEventListener, m_screens.at(0)->root(),
-                      0, 0, 1, 1, 0, XCB_WINDOW_CLASS_INPUT_ONLY,
-                      m_screens.at(0)->screen()->root_visual, 0, 0);
-
     m_keyboard = new QXcbKeyboard(this);
 
     initializeAllAtoms();
@@ -128,50 +121,15 @@ QXcbConnection::QXcbConnection(const char *displayName)
     initializeDri2();
 #endif
 
-    start();
-}
+    QSocketNotifier *notifier = new QSocketNotifier(xcb_get_file_descriptor(xcb_connection()), QSocketNotifier::Read, this);
+    connect(notifier, SIGNAL(activated(int)), this, SLOT(processXcbEvents()));
 
-void QXcbConnection::sendConnectionEvent(QXcbAtom::Atom atom, uint id)
-{
-    xcb_client_message_event_t event;
-    memset(&event, 0, sizeof(event));
-
-    event.response_type = XCB_CLIENT_MESSAGE;
-    event.format = 32;
-    event.sequence = 0;
-    event.window = m_connectionEventListener;
-    event.type = atom;
-    event.data.data32[0] = id;
-
-    Q_XCB_CALL(xcb_send_event(xcb_connection(), false, m_connectionEventListener, XCB_EVENT_MASK_NO_EVENT, (const char *)&event));
-    xcb_flush(xcb_connection());
-}
-
-void QXcbConnection::setEventProcessingEnabled(bool enabled)
-{
-    if (enabled == m_enabled)
-        return;
-
-    if (!enabled) {
-        sendConnectionEvent(QXcbAtom::_QT_PAUSE_CONNECTION, uint(m_pauseId));
-        m_connectionLock.lock();
-        m_pauseId.fetchAndAddOrdered(1);
-    } else {
-        m_connectionLock.unlock();
-        m_connectionWaitCondition.wakeAll();
-    }
-
-    m_enabled = enabled;
+    QAbstractEventDispatcher *dispatcher = QAbstractEventDispatcher::instance(qApp->thread());
+    connect(dispatcher, SIGNAL(awake()), this, SLOT(processXcbEvents()));
 }
 
 QXcbConnection::~QXcbConnection()
 {
-    setEventProcessingEnabled(true);
-
-    sendConnectionEvent(QXcbAtom::_QT_CLOSE_CONNECTION);
-    wait();
-
-    xcb_destroy_window(xcb_connection(), m_connectionEventListener);
     qDeleteAll(m_screens);
 
 #ifdef XCB_USE_XLIB
@@ -417,128 +375,93 @@ void QXcbConnection::log(const char *file, int line, int sequence)
     info.sequence = sequence;
     info.file = file;
     info.line = line;
-
-    QMutexLocker locker(&m_callLogMutex);
-    m_callLog << info;
 }
 #endif
 
-void QXcbConnection::run()
+void QXcbConnection::processXcbEvents()
 {
-    QMutexLocker locker(&m_connectionLock);
-    fd_set readset;
-    int xcb_fd = xcb_get_file_descriptor(xcb_connection());
-    FD_ZERO(&readset);
-    FD_SET(xcb_fd, &readset);
-    int result;
-    while (true) {
-        while (xcb_generic_event_t *event = xcb_poll_for_event(xcb_connection())) {
-            bool handled = true;
-
-            uint response_type = event->response_type & ~0x80;
-
-            if (!response_type) {
-                xcb_generic_error_t *error = (xcb_generic_error_t *)event;
-
-                uint clamped_error_code = qMin<uint>(error->error_code, (sizeof(xcb_errors) / sizeof(xcb_errors[0])) - 1);
-                uint clamped_major_code = qMin<uint>(error->major_code, (sizeof(xcb_protocol_request_codes) / sizeof(xcb_protocol_request_codes[0])) - 1);
-
-                printf("XCB error: %d (%s), sequence: %d, resource id: %d, major code: %d (%s), minor code: %d\n",
-                       int(error->error_code), xcb_errors[clamped_error_code],
-                       int(error->sequence), int(error->resource_id),
-                       int(error->major_code), xcb_protocol_request_codes[clamped_major_code],
-                       int(error->minor_code));
-#ifdef Q_XCB_DEBUG
-                QMutexLocker locker(&m_callLogMutex);
-                int i = 0;
-                for (; i < m_callLog.size(); ++i) {
-                    if (m_callLog.at(i).sequence == error->sequence) {
-                        printf("Caused by: %s:%d\n", qPrintable(m_callLog.at(i).file), m_callLog.at(i).line);
-                        break;
-                    } else if (m_callLog.at(i).sequence > error->sequence) {
-                        printf("Caused some time before: %s:%d\n", qPrintable(m_callLog.at(i).file), m_callLog.at(i).line);
-                        if (i > 0)
-                            printf("and after: %s:%d\n", qPrintable(m_callLog.at(i-1).file), m_callLog.at(i-1).line);
-                        break;
-                    }
-                }
-                if (i == m_callLog.size() && !m_callLog.isEmpty())
-                    printf("Caused some time after: %s:%d\n", qPrintable(m_callLog.first().file), m_callLog.first().line);
-#endif
-                continue;
-            }
+    while (xcb_generic_event_t *event = xcb_poll_for_event(xcb_connection())) {
+        bool handled = true;
 
-#ifdef Q_XCB_DEBUG
-            {
-                QMutexLocker locker(&m_callLogMutex);
-                int i = 0;
-                for (; i < m_callLog.size(); ++i)
-                    if (m_callLog.at(i).sequence >= event->sequence)
-                        break;
-                m_callLog.remove(0, i);
-            }
-#endif
+        uint response_type = event->response_type & ~0x80;
 
-            if (response_type == XCB_CLIENT_MESSAGE) {
-                xcb_client_message_event_t *ev = (xcb_client_message_event_t *)event;
+        if (!response_type) {
+            xcb_generic_error_t *error = (xcb_generic_error_t *)event;
 
-                if (ev->type == QXcbAtom::_QT_CLOSE_CONNECTION)
-                    return;
+            uint clamped_error_code = qMin<uint>(error->error_code, (sizeof(xcb_errors) / sizeof(xcb_errors[0])) - 1);
+            uint clamped_major_code = qMin<uint>(error->major_code, (sizeof(xcb_protocol_request_codes) / sizeof(xcb_protocol_request_codes[0])) - 1);
 
-                if (ev->type == QXcbAtom::_QT_PAUSE_CONNECTION) {
-                    if (ev->data.data32[0] == uint(m_pauseId))
-                        m_connectionWaitCondition.wait(&m_connectionLock);
-                    continue;
+            printf("XCB error: %d (%s), sequence: %d, resource id: %d, major code: %d (%s), minor code: %d\n",
+                   int(error->error_code), xcb_errors[clamped_error_code],
+                   int(error->sequence), int(error->resource_id),
+                   int(error->major_code), xcb_protocol_request_codes[clamped_major_code],
+                   int(error->minor_code));
+#ifdef Q_XCB_DEBUG
+            int i = 0;
+            for (; i < m_callLog.size(); ++i) {
+                if (m_callLog.at(i).sequence == error->sequence) {
+                    printf("Caused by: %s:%d\n", qPrintable(m_callLog.at(i).file), m_callLog.at(i).line);
+                    break;
+                } else if (m_callLog.at(i).sequence > error->sequence) {
+                    printf("Caused some time before: %s:%d\n", qPrintable(m_callLog.at(i).file), m_callLog.at(i).line);
+                    if (i > 0)
+                        printf("and after: %s:%d\n", qPrintable(m_callLog.at(i-1).file), m_callLog.at(i-1).line);
+                    break;
                 }
             }
-
-            switch (response_type) {
-            case XCB_EXPOSE:
-                HANDLE_PLATFORM_WINDOW_EVENT(xcb_expose_event_t, window, handleExposeEvent);
-            case XCB_BUTTON_PRESS:
-                HANDLE_PLATFORM_WINDOW_EVENT(xcb_button_press_event_t, event, handleButtonPressEvent);
-            case XCB_BUTTON_RELEASE:
-                HANDLE_PLATFORM_WINDOW_EVENT(xcb_button_release_event_t, event, handleButtonReleaseEvent);
-            case XCB_MOTION_NOTIFY:
-                HANDLE_PLATFORM_WINDOW_EVENT(xcb_motion_notify_event_t, event, handleMotionNotifyEvent);
-            case XCB_CONFIGURE_NOTIFY:
-                HANDLE_PLATFORM_WINDOW_EVENT(xcb_configure_notify_event_t, event, handleConfigureNotifyEvent);
-            case XCB_CLIENT_MESSAGE:
-                HANDLE_PLATFORM_WINDOW_EVENT(xcb_client_message_event_t, window, handleClientMessageEvent);
-            case XCB_ENTER_NOTIFY:
-                HANDLE_PLATFORM_WINDOW_EVENT(xcb_enter_notify_event_t, event, handleEnterNotifyEvent);
-            case XCB_LEAVE_NOTIFY:
-                HANDLE_PLATFORM_WINDOW_EVENT(xcb_leave_notify_event_t, event, handleLeaveNotifyEvent);
-            case XCB_FOCUS_IN:
-                HANDLE_PLATFORM_WINDOW_EVENT(xcb_focus_in_event_t, event, handleFocusInEvent);
-            case XCB_FOCUS_OUT:
-                HANDLE_PLATFORM_WINDOW_EVENT(xcb_focus_out_event_t, event, handleFocusOutEvent);
-            case XCB_KEY_PRESS:
-                HANDLE_KEYBOARD_EVENT(xcb_key_press_event_t, handleKeyPressEvent);
-            case XCB_KEY_RELEASE:
-                HANDLE_KEYBOARD_EVENT(xcb_key_release_event_t, handleKeyReleaseEvent);
-            case XCB_MAPPING_NOTIFY:
-                m_keyboard->handleMappingNotifyEvent((xcb_mapping_notify_event_t *)event);
-                break;
-            default:
-                handled = false;
-                break;
-            }
-            if (handled)
-                printXcbEvent("Handled XCB event", event);
-            else
-                printXcbEvent("Unhandled XCB event", event);
+            if (i == m_callLog.size() && !m_callLog.isEmpty())
+                printf("Caused some time after: %s:%d\n", qPrintable(m_callLog.first().file), m_callLog.first().line);
+#endif
+            continue;
         }
 
-        do {
-            result = select(xcb_fd + 1, &readset, 0, 0, 0);
-        } while (result == -1 && errno == EINTR);
-
-        if (result <= 0 || !FD_ISSET(xcb_fd, &readset))
-            continue;
+#ifdef Q_XCB_DEBUG
+        {
+            int i = 0;
+            for (; i < m_callLog.size(); ++i)
+                if (m_callLog.at(i).sequence >= event->sequence)
+                    break;
+            m_callLog.remove(0, i);
+        }
+#endif
 
+        switch (response_type) {
+        case XCB_EXPOSE:
+            HANDLE_PLATFORM_WINDOW_EVENT(xcb_expose_event_t, window, handleExposeEvent);
+        case XCB_BUTTON_PRESS:
+            HANDLE_PLATFORM_WINDOW_EVENT(xcb_button_press_event_t, event, handleButtonPressEvent);
+        case XCB_BUTTON_RELEASE:
+            HANDLE_PLATFORM_WINDOW_EVENT(xcb_button_release_event_t, event, handleButtonReleaseEvent);
+        case XCB_MOTION_NOTIFY:
+            HANDLE_PLATFORM_WINDOW_EVENT(xcb_motion_notify_event_t, event, handleMotionNotifyEvent);
+        case XCB_CONFIGURE_NOTIFY:
+            HANDLE_PLATFORM_WINDOW_EVENT(xcb_configure_notify_event_t, event, handleConfigureNotifyEvent);
+        case XCB_CLIENT_MESSAGE:
+            HANDLE_PLATFORM_WINDOW_EVENT(xcb_client_message_event_t, window, handleClientMessageEvent);
+        case XCB_ENTER_NOTIFY:
+            HANDLE_PLATFORM_WINDOW_EVENT(xcb_enter_notify_event_t, event, handleEnterNotifyEvent);
+        case XCB_LEAVE_NOTIFY:
+            HANDLE_PLATFORM_WINDOW_EVENT(xcb_leave_notify_event_t, event, handleLeaveNotifyEvent);
+        case XCB_FOCUS_IN:
+            HANDLE_PLATFORM_WINDOW_EVENT(xcb_focus_in_event_t, event, handleFocusInEvent);
+        case XCB_FOCUS_OUT:
+            HANDLE_PLATFORM_WINDOW_EVENT(xcb_focus_out_event_t, event, handleFocusOutEvent);
+        case XCB_KEY_PRESS:
+            HANDLE_KEYBOARD_EVENT(xcb_key_press_event_t, handleKeyPressEvent);
+        case XCB_KEY_RELEASE:
+            HANDLE_KEYBOARD_EVENT(xcb_key_release_event_t, handleKeyReleaseEvent);
+        case XCB_MAPPING_NOTIFY:
+            m_keyboard->handleMappingNotifyEvent((xcb_mapping_notify_event_t *)event);
+            break;
+        default:
+            handled = false;
+            break;
+        }
+        if (handled)
+            printXcbEvent("Handled XCB event", event);
+        else
+            printXcbEvent("Unhandled XCB event", event);
     }
-    fprintf(stderr, "I/O error in xcb_wait_for_event\n");
 }
 
 static const char * xcb_atomnames = {
@@ -580,9 +503,6 @@ static const char * xcb_atomnames = {
     "_QT_SCROLL_DONE\0"
     "_QT_INPUT_ENCODING\0"
 
-    "_QT_CLOSE_CONNECTION\0"
-    "_QT_PAUSE_CONNECTION\0"
-
     "_MOTIF_WM_HINTS\0"
 
     "DTWM_IS_RUNNING\0"
@@ -738,13 +658,8 @@ void QXcbConnection::initializeAllAtoms() {
 void QXcbConnection::sync()
 {
     // from xcb_aux_sync
-    bool wasEnabled = m_enabled;
-    setEventProcessingEnabled(false);
     xcb_get_input_focus_cookie_t cookie = Q_XCB_CALL(xcb_get_input_focus(xcb_connection()));
     free(xcb_get_input_focus_reply(xcb_connection(), cookie, 0));
-
-    if (wasEnabled)
-        setEventProcessingEnabled(true);
 }
 
 #if defined(XCB_USE_EGL)
diff --git a/src/plugins/platforms/xcb/qxcbconnection.h b/src/plugins/platforms/xcb/qxcbconnection.h
index 7088184..53846f1 100644
--- a/src/plugins/platforms/xcb/qxcbconnection.h
+++ b/src/plugins/platforms/xcb/qxcbconnection.h
@@ -44,10 +44,8 @@
 #include <xcb/xcb.h>
 
 #include <QList>
-#include <QMutex>
+#include <QObject>
 #include <QVector>
-#include <QWaitCondition>
-#include <QThread>
 
 #define Q_XCB_DEBUG
 
@@ -93,10 +91,6 @@ namespace QXcbAtom {
         _QT_SCROLL_DONE,
         _QT_INPUT_ENCODING,
 
-        // Qt/XCB specific
-        _QT_CLOSE_CONNECTION,
-        _QT_PAUSE_CONNECTION,
-
         _MOTIF_WM_HINTS,
 
         DTWM_IS_RUNNING,
@@ -222,7 +216,7 @@ namespace QXcbAtom {
 
 class QXcbKeyboard;
 
-class QXcbConnection : public QThread
+class QXcbConnection : public QObject
 {
     Q_OBJECT
 public:
@@ -242,8 +236,6 @@ public:
 
     QXcbKeyboard *keyboard() const { return m_keyboard; }
 
-    void setEventProcessingEnabled(bool enabled);
-
 #ifdef XCB_USE_XLIB
     void *xlib_display() const { return m_xlib_display; }
 #endif
@@ -261,8 +253,8 @@ public:
 
     void sync();
 
-protected:
-    void run();
+private slots:
+    void processXcbEvents();
 
 private:
     void initializeAllAtoms();
@@ -281,12 +273,6 @@ private:
 
     QByteArray m_displayName;
 
-    xcb_window_t m_connectionEventListener;
-    QMutex m_connectionLock;
-    QWaitCondition m_connectionWaitCondition;
-    QAtomicInt m_pauseId;
-    bool m_enabled;
-
     QXcbKeyboard *m_keyboard;
 
 #if defined(XCB_USE_XLIB)
@@ -311,7 +297,6 @@ private:
         int line;
     };
     QVector<CallInfo> m_callLog;
-    QMutex m_callLogMutex;
     void log(const char *file, int line, int sequence);
     template <typename cookie_t>
     friend cookie_t q_xcb_call_template(const cookie_t &cookie, QXcbConnection *connection, const char *file, int line);
diff --git a/src/plugins/platforms/xcb/qxcbwindow.cpp b/src/plugins/platforms/xcb/qxcbwindow.cpp
index 7aeb557..1f4a13c 100644
--- a/src/plugins/platforms/xcb/qxcbwindow.cpp
+++ b/src/plugins/platforms/xcb/qxcbwindow.cpp
@@ -113,7 +113,6 @@ QXcbWindow::QXcbWindow(QWidget *tlw)
     if (tlw->platformWindowFormat().windowApi() == QPlatformWindowFormat::OpenGL
         && QApplicationPrivate::platformIntegration()->hasOpenGL())
     {
-        connection()->setEventProcessingEnabled(false);
 #if defined(XCB_USE_GLX)
         XVisualInfo *visualInfo = qglx_findVisualInfo(DISPLAY_FROM_XCB(m_screen),m_screen->screenNumber(), tlw->platformWindowFormat());
 #elif defined(XCB_USE_EGL)
@@ -142,7 +141,6 @@ QXcbWindow::QXcbWindow(QWidget *tlw)
         } else {
             qFatal("no window!");
         }
-        connection()->setEventProcessingEnabled(true);
     } else
 #endif //defined(XCB_USE_GLX) || defined(XCB_USE_EGL)
     {
@@ -431,7 +429,6 @@ QPlatformGLContext *QXcbWindow::glContext() const
         return 0;
     }
     if (!m_context) {
-        connection()->setEventProcessingEnabled(false);
 #if defined(XCB_USE_GLX)
         QXcbWindow *that = const_cast<QXcbWindow *>(this);
         that->m_context = new QGLXContext(m_window, m_screen, widget()->platformWindowFormat());
@@ -450,7 +447,6 @@ QPlatformGLContext *QXcbWindow::glContext() const
         QXcbWindow *that = const_cast<QXcbWindow *>(this);
         that->m_context = new QDri2Context(that);
 #endif
-        connection()->setEventProcessingEnabled(true);
     }
     return m_context;
 }
diff --git a/src/plugins/platforms/xcb/qxcbwindowsurface.cpp b/src/plugins/platforms/xcb/qxcbwindowsurface.cpp
index 4c0d862..a4607dc 100644
--- a/src/plugins/platforms/xcb/qxcbwindowsurface.cpp
+++ b/src/plugins/platforms/xcb/qxcbwindowsurface.cpp
@@ -62,7 +62,7 @@ public:
     QImage *image() { return &m_qimage; }
 
     void put(xcb_window_t window, const QPoint &dst, const QRect &source);
-    void preparePaint(const QRegion &region, QMutex *mutex);
+    void preparePaint(const QRegion &region);
 
 private:
     void destroy();
@@ -148,15 +148,12 @@ void QXcbShmImage::put(xcb_window_t window, const QPoint &target, const QRect &s
     Q_XCB_NOOP(connection());
 }
 
-void QXcbShmImage::preparePaint(const QRegion &region, QMutex *mutex)
+void QXcbShmImage::preparePaint(const QRegion &region)
 {
     // to prevent X from reading from the image region while we're writing to it
     if (m_dirty.intersects(region)) {
         connection()->sync();
-        mutex->lock();
         m_dirty = QRegion();
-    } else {
-        mutex->lock();
     }
 }
 
@@ -170,7 +167,6 @@ QXcbWindowSurface::QXcbWindowSurface(QWidget *widget, bool setDefaultSurface)
 
 QXcbWindowSurface::~QXcbWindowSurface()
 {
-    QMutexLocker locker(&m_surfaceLock);
     delete m_image;
 }
 
@@ -181,12 +177,11 @@ QPaintDevice *QXcbWindowSurface::paintDevice()
 
 void QXcbWindowSurface::beginPaint(const QRegion &region)
 {
-    m_image->preparePaint(region, &m_surfaceLock);
+    m_image->preparePaint(region);
 }
 
 void QXcbWindowSurface::endPaint(const QRegion &)
 {
-    m_surfaceLock.unlock();
 }
 
 void QXcbWindowSurface::flush(QWidget *widget, const QRegion &region, const QPoint &offset)
@@ -201,8 +196,6 @@ void QXcbWindowSurface::flush(QWidget *widget, const QRegion &region, const QPoi
     extern QWidgetData* qt_widget_data(QWidget *);
     QPoint widgetOffset = qt_qwidget_data(widget)->wrect.topLeft();
 
-    QMutexLocker locker(&m_surfaceLock);
-
     QVector<QRect> rects = region.rects();
     for (int i = 0; i < rects.size(); ++i)
         m_image->put(window->window(), rects.at(i).topLeft() - widgetOffset, rects.at(i).translated(offset));
@@ -217,15 +210,9 @@ void QXcbWindowSurface::resize(const QSize &size)
 
     QXcbScreen *screen = static_cast<QXcbScreen *>(QPlatformScreen::platformScreenForWidget(window()));
 
-    connection()->setEventProcessingEnabled(false);
-    m_surfaceLock.lock();
-
     delete m_image;
     m_image = new QXcbShmImage(screen, size);
     Q_XCB_NOOP(connection());
-
-    m_surfaceLock.unlock();
-    connection()->setEventProcessingEnabled(true);
 }
 
 extern void qt_scrollRectInImage(QImage &img, const QRect &rect, const QPoint &offset);
@@ -235,14 +222,12 @@ bool QXcbWindowSurface::scroll(const QRegion &area, int dx, int dy)
     if (m_image->image()->isNull())
         return false;
 
-    m_image->preparePaint(area, &m_surfaceLock);
+    m_image->preparePaint(area);
 
     const QVector<QRect> rects = area.rects();
     for (int i = 0; i < rects.size(); ++i)
         qt_scrollRectInImage(*m_image->image(), rects.at(i), QPoint(dx, dy));
 
-    m_surfaceLock.unlock();
-
     return true;
 }
 
diff --git a/src/plugins/platforms/xcb/qxcbwindowsurface.h b/src/plugins/platforms/xcb/qxcbwindowsurface.h
index e508fe6..f87e122 100644
--- a/src/plugins/platforms/xcb/qxcbwindowsurface.h
+++ b/src/plugins/platforms/xcb/qxcbwindowsurface.h
@@ -48,8 +48,6 @@
 
 #include "qxcbobject.h"
 
-#include <QMutex>
-
 class QXcbShmImage;
 
 class QXcbWindowSurface : public QXcbObject, public QWindowSurface
@@ -68,7 +66,6 @@ public:
 
 private:
     QXcbShmImage *m_image;
-    QMutex m_surfaceLock;
 };
 
 #endif