x = pa[k - 1]; y = x->rtrb_link[1]; x->rtrb_link[1] = y->rtrb_link[0]; y->rtrb_link[0] = x; pa[k - 2]->rtrb_link[0] = y; if (x->rtrb_link[1] == NULL) { x->rtrb_rtag = RTRB_THREAD; x->rtrb_link[1] = y; }