Deadlock QImage::scaled

template<typename T>
static inline void multithread_pixels_function(QImageScaleInfo *isi, int dh, const T &scaleSection)
{
#if QT_CONFIG(thread) && !defined(Q_OS_WASM)
    int segments = (qsizetype(isi->sh) * isi->sw) / (1<<16);
    segments = std::min(segments, dh);
    QThreadPool *threadPool = QThreadPoolPrivate::qtGuiInstance();
    if (segments > 1 && threadPool && !threadPool->contains(QThread::currentThread())) {
        QSemaphore semaphore;
        int y = 0;
        for (int i = 0; i < segments; ++i) {
            int yn = (dh - y) / (segments - i);
            threadPool->start([&, y, yn]() {
                scaleSection(y, y + yn);
                semaphore.release(1);
            });
            y += yn;
        }
        semaphore.acquire(segments);
        return;
    }
#endif
    scaleSection(0, dh);
}