release (&rwlock->rw_spinlock);
__pthread_unlock (&rwlock->rw_lock);
pthread_rwlock_tryrdlock (pthread_rwlock_t *rwlock){  int result = EBUSY;  acquire (&rwlock->rw_spinlock);  if (rwlock->rw_writer == NULL      || (rwlock->rw_kind == PTHREAD_RWLOCK_PREFER_READER_NP	  && rwlock->rw_readers != 0))    {      ++rwlock->rw_readers;      result = 0;    }  release (&rwlock->rw_spinlock);  return result;}