client: Fix crash on shutdown on Mesa driver

On Wayland, then the mesa driver is in use, calling
eglDestroySurface() while OpenGL commands are being
executed may crash. While this means the driver does
not operate by the specs in this case, the driver is
so popular that it makes sense to work around it.

To work around this, we read-lock the surface while
rendering and wait for a write-lock before we destroy
the EGL surface.

[ChangeLog][QtWaylandClient] Fixed a crash on shutdown that could
happen with some graphics-heavy applications when running on Mesa
drivers.

Pick-to: 6.3
Fixes: QTBUG-92249
Change-Id: I8b8461066cc9f948dc44ddeeddaa6e7d92b76f04
Reviewed-by: Liang Qi <liang.qi@qt.io>

4 files changed, 43 insertions, 13 deletions

diff --git a/src/client/qwaylandwindow.cpp b/src/client/qwaylandwindow.cpp
index 3481a8fa2..0b4347a88 100644
--- a/src/client/qwaylandwindow.cpp
+++ b/src/client/qwaylandwindow.cpp
@@ -77,6 +77,7 @@ QWaylandWindow::QWaylandWindow(QWindow *window, QWaylandDisplay *display)
     : QPlatformWindow(window)
     , mDisplay(display)
     , mResizeAfterSwap(qEnvironmentVariableIsSet("QT_WAYLAND_RESIZE_AFTER_SWAP"))
+    , mSurfaceLock(QReadWriteLock::Recursive)
 {
     {
         bool ok;
@@ -235,6 +236,16 @@ bool QWaylandWindow::shouldCreateSubSurface() const
     return QPlatformWindow::parent() != nullptr;
 }
 
+void QWaylandWindow::beginFrame()
+{
+    mSurfaceLock.lockForRead();
+}
+
+void QWaylandWindow::endFrame()
+{
+    mSurfaceLock.unlock();
+}
+
 void QWaylandWindow::reset()
 {
     delete mShellSurface;
@@ -242,10 +253,10 @@ void QWaylandWindow::reset()
     delete mSubSurfaceWindow;
     mSubSurfaceWindow = nullptr;
 
-    invalidateSurface();
     if (mSurface) {
         emit wlSurfaceDestroyed();
         QWriteLocker lock(&mSurfaceLock);
+        invalidateSurface();
         mSurface.reset();
     }
 
diff --git a/src/client/qwaylandwindow_p.h b/src/client/qwaylandwindow_p.h
index 4eecdd861..d64c80c41 100644
--- a/src/client/qwaylandwindow_p.h
+++ b/src/client/qwaylandwindow_p.h
@@ -233,6 +233,9 @@ public:
     void setXdgActivationToken(const QString &token);
     void requestXdgActivationToken(uint serial);
 
+    void beginFrame();
+    void endFrame();
+
 public slots:
     void applyConfigure();
 
diff --git a/src/hardwareintegration/client/wayland-egl/qwaylandglcontext.cpp b/src/hardwareintegration/client/wayland-egl/qwaylandglcontext.cpp
index 65ec22f1f..e9b290a76 100644
--- a/src/hardwareintegration/client/wayland-egl/qwaylandglcontext.cpp
+++ b/src/hardwareintegration/client/wayland-egl/qwaylandglcontext.cpp
@@ -300,6 +300,18 @@ QWaylandGLContext::~QWaylandGLContext()
         eglDestroyContext(eglDisplay(), m_decorationsContext);
 }
 
+void QWaylandGLContext::beginFrame()
+{
+    Q_ASSERT(m_currentWindow != nullptr);
+    m_currentWindow->beginFrame();
+}
+
+void QWaylandGLContext::endFrame()
+{
+    Q_ASSERT(m_currentWindow != nullptr);
+    m_currentWindow->endFrame();
+}
+
 bool QWaylandGLContext::makeCurrent(QPlatformSurface *surface)
 {
     // in QWaylandGLContext() we called eglBindAPI with the correct value. However,
@@ -311,10 +323,10 @@ bool QWaylandGLContext::makeCurrent(QPlatformSurface *surface)
         eglBindAPI(m_api);
     }
 
-    QWaylandEglWindow *window = static_cast<QWaylandEglWindow *>(surface);
-    EGLSurface eglSurface = window->eglSurface();
+    m_currentWindow = static_cast<QWaylandEglWindow *>(surface);
+    EGLSurface eglSurface = m_currentWindow->eglSurface();
 
-    if (!window->needToUpdateContentFBO() && (eglSurface != EGL_NO_SURFACE)) {
+    if (!m_currentWindow->needToUpdateContentFBO() && (eglSurface != EGL_NO_SURFACE)) {
         if (!eglMakeCurrent(eglDisplay(), eglSurface, eglSurface, eglContext())) {
             qWarning("QWaylandGLContext::makeCurrent: eglError: %x, this: %p \n", eglGetError(), this);
             return false;
@@ -322,26 +334,26 @@ bool QWaylandGLContext::makeCurrent(QPlatformSurface *surface)
         return true;
     }
 
-    if (window->isExposed())
-        window->setCanResize(false);
-    if (m_decorationsContext != EGL_NO_CONTEXT && !window->decoration())
-        window->createDecoration();
+    if (m_currentWindow->isExposed())
+        m_currentWindow->setCanResize(false);
+    if (m_decorationsContext != EGL_NO_CONTEXT && !m_currentWindow->decoration())
+        m_currentWindow->createDecoration();
 
     if (eglSurface == EGL_NO_SURFACE) {
-        window->updateSurface(true);
-        eglSurface = window->eglSurface();
+        m_currentWindow->updateSurface(true);
+        eglSurface = m_currentWindow->eglSurface();
     }
 
     if (!eglMakeCurrent(eglDisplay(), eglSurface, eglSurface, eglContext())) {
         qWarning("QWaylandGLContext::makeCurrent: eglError: %x, this: %p \n", eglGetError(), this);
-        window->setCanResize(true);
+        m_currentWindow->setCanResize(true);
         return false;
     }
 
     //### setCurrentContext will be called in QOpenGLContext::makeCurrent after this function
     // returns, but that's too late, as we need a current context in order to bind the content FBO.
     QOpenGLContextPrivate::setCurrentContext(context());
-    window->bindContentFBO();
+    m_currentWindow->bindContentFBO();
 
     return true;
 }
diff --git a/src/hardwareintegration/client/wayland-egl/qwaylandglcontext_p.h b/src/hardwareintegration/client/wayland-egl/qwaylandglcontext_p.h
index 678a7695e..e43bc653d 100644
--- a/src/hardwareintegration/client/wayland-egl/qwaylandglcontext_p.h
+++ b/src/hardwareintegration/client/wayland-egl/qwaylandglcontext_p.h
@@ -64,7 +64,7 @@ class QOpenGLTextureCache;
 
 namespace QtWaylandClient {
 
-class QWaylandWindow;
+class QWaylandEglWindow;
 class DecorationsBlitter;
 
 class Q_WAYLAND_CLIENT_EXPORT QWaylandGLContext : public QEGLPlatformContext
@@ -77,6 +77,9 @@ public:
     bool makeCurrent(QPlatformSurface *surface) override;
     void doneCurrent() override;
 
+    void beginFrame() override;
+    void endFrame() override;
+
     GLuint defaultFramebufferObject(QPlatformSurface *surface) const override;
 
     QFunctionPointer getProcAddress(const char *procName) override;
@@ -94,6 +97,7 @@ private:
     EGLenum m_api;
     wl_surface *m_wlSurface = nullptr;
     wl_egl_window *m_eglWindow = nullptr;
+    QWaylandEglWindow *m_currentWindow = nullptr;
 };
 
 }