casip
if (casip(&lp->rw_wwwh, old, old + lock_value) != old) {
} while (old != new && casip(&lp->rw_wwwh, old, new) != old);
if (casip(&lp->rw_wwwh, old, new) != old) {
if (casip(&lp->rw_wwwh, old, new) != old)
if (casip(&lp->rw_wwwh, old, old + RW_READ_LOCK) == old)
if (casip(&lp->rw_wwwh, 0, RW_WRITE_LOCK(curthread)) != 0)
} while (casip(&lp->rw_wwwh, old, new) != old);
casip(&(lp)->m_owner, old, old | MUTEX_WAITERS) != old) \
casip(&(lp)->m_owner, old, old | MUTEX_WAITERS) != old) \