ST_VP_RUNNING
vp->state &= ~(ST_VP_PENDING | ST_VP_RUNNING | ST_VP_OFF |
ret = (vp->state & ST_VP_RUNNING) || (vp->state & ST_VP_PENDING);
if (!list_empty(&vp->pending_buf_q) && (vp->state & ST_VP_RUNNING) &&
vp->state |= ST_VP_RUNNING;