PIPE_RESTART
if (wakeup_state & PIPE_RESTART) {
rpipe->pipe_state &= ~PIPE_RESTART;
wpipe->pipe_state &= ~PIPE_RESTART;
if (wakeup_state & PIPE_RESTART) {
wpipe->pipe_state &= ~PIPE_RESTART;
pipe->pipe_state |= PIPE_RESTART;