2111   PerThreadSynch* old_h = nullptr;  in UnlockSlow()  local
2203       ABSL_RAW_CHECK(old_h == nullptr || h->maybe_unlocking,  in UnlockSlow()
2207       if (old_h != nullptr &&  in UnlockSlow()
2208           !old_h->may_skip) {    // we used old_h as a terminator  in UnlockSlow()
2209         old_h->may_skip = true;  // allow old_h to skip once more  in UnlockSlow()
2210         ABSL_RAW_CHECK(old_h->skip == nullptr, "illegal skip from head");  in UnlockSlow()
2211         if (h != old_h && MuEquivalentWaiter(old_h, old_h->next)) {  in UnlockSlow()
2212           old_h->skip = old_h->next;  // old_h not head & can skip to successor  in UnlockSlow()
2229       } else if (w != nullptr && (w->waitp->how == kExclusive || h == old_h)) {  in UnlockSlow()
2241         if (old_h == h) {  // we've searched before, and nothing's new  in UnlockSlow()
2263         if (old_h != nullptr) {  // we've searched up to old_h before  in UnlockSlow()
2264           pw_walk = old_h;  in UnlockSlow()
2265           w_walk = old_h->next;  in UnlockSlow()
2292         old_h = h;  // remember we searched to here  in UnlockSlow()