readRank lockRank // semantic lock rank for read locking
}

// Lock ranking an rwmutex has two aspects:
//
// Semantic ranking: this rwmutex represents some higher level lock that
// protects some resource (e.g., allocmLock protects creation of new Ms). The
// read and write locks of that resource need to be represented in the lock
// rank.
//
// Internal ranking: as an implementation detail, rwmutex uses two mutexes: