c++11 use conditional variable in signal handler

Is it safe to use std::conditional_variable::notify_one in signal handler. Example:

enum State {}; State state;

// worker thread
std::tread th = std::thread([]()
{
    std::unique_lock lc(mutex);
    cv.wait(lc, []() { return state; });
});

//signal handler
handler(int sig)
{
    if (sig == SOME_SIG)
    {
        std::unique_lock lc(mutex);
        state = Do;
        cv.notify_one();
    }
}