From c3960e59979f3a71d6f1c1bef0bfcb4c0dc2153f Mon Sep 17 00:00:00 2001 From: Pavel Tumakaev Date: Wed, 31 Jul 2019 13:26:51 +0300 Subject: [PATCH] Fix deadlock in QWaylandWindow::waitForFrameSync Calling the QOpenGLContext::swapBuffers from QGuiApplicationPrivate::processExposeEvent in some cases leads to recursive calls of QWaylandWindow::waitForFrameSync. Since the mWaitingForFrameCallback check in WaylandWindow::waitForFrameSync is performed after the mutex is locked, the QMutexLocker tries to lock the mFrameSyncMutex mutex in every recursive call, that leads to a deadlock. This patch moves the performing of the mWaitingForFrameCallback check before locking the mutex. Change-Id: Ia2d834b7dd03fcd91bbe29a3a897b4db2d155527 Reviewed-by: Johan Helsing --- src/plugins/platforms/wayland/qwaylandwindow.cpp | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/src/plugins/platforms/wayland/qwaylandwindow.cpp b/src/plugins/platforms/wayland/qwaylandwindow.cpp index abc54f58438..95358232316 100644 --- a/src/plugins/platforms/wayland/qwaylandwindow.cpp +++ b/src/plugins/platforms/wayland/qwaylandwindow.cpp @@ -657,10 +657,11 @@ QMutex QWaylandWindow::mFrameSyncMutex; bool QWaylandWindow::waitForFrameSync(int timeout) { - QMutexLocker locker(&mFrameSyncMutex); if (!mWaitingForFrameCallback) return true; + QMutexLocker locker(&mFrameSyncMutex); + wl_proxy_set_queue(reinterpret_cast(mFrameCallback), mFrameQueue); mDisplay->dispatchQueueWhile(mFrameQueue, [&]() { return mWaitingForFrameCallback; }, timeout);