8b50d2c6cc
This race happened because QWaylandIntegration::clientBufferIntegration (which lazily initializes the integration) was called from numerous places including code that may run on different threads without any kind of syncrhonization. An example of this is Qt3D, which indirectly and simultaneously calls createPlatformWindow (from the GUI thread) and createPlatformOpenGLContext (from its render thread), both of which needs to use the client buffer integration. In this patch, we fix it by first checking if the integration is initialized. In that case, it's safe to use it. Otherwise we lock a mutex, re-check if initialization has happened on another thread in the meantime, and then finally we initialize it. This way we should avoid the expense of mutex locking after initialization is complete, while still staying race free during initialization. Fixes: QTBUG-76504 Change-Id: I327840ebf41e014882cb659bc3e4fafb7bdb7a98 Reviewed-by: David Edmundson <davidedmundson@kde.org> Reviewed-by: Paul Olav Tvete <paul.tvete@qt.io>