double_rq_lock
guard(double_rq_lock)(src_rq, dst_rq);
guard(double_rq_lock)(dst, src);
double_rq_lock(this_rq, busiest);
double_rq_lock(this_rq, busiest);
DEFINE_LOCK_GUARD_2(double_rq_lock, struct rq,
double_rq_lock(_T->lock, _T->lock2),
guard(double_rq_lock)(rq, p_rq);