Is it ok to unlock a mutex twice in Qt 5.4?

The code is as following:

waitmutex.lock(); //waitmutex is a QMutex
int tout=4000;
if(!waitc.wait(&waitmutex,tout))
{
    waitmutex.unlock(); // unlock first time
    mutex.lock();
    if(tileCacheQueue.count()==0)
    {
        mutex.unlock();
        break;
    }
    mutex.unlock();
}
waitmutex.unlock();// unlock the second time possibly?

Will the code possibly results in the waitmutex to be unlocked twice? Is this a problem in Qt?