pthread_rwlock_destroy( ) function shall destroy the read-write lock object referenced by rwlock and release any resources used by the lock. If successful, the pthread_rwlock_destroy( ) return zero; otherwise, an error number shall be returned to indicate the error. If not successful, pthread_rwlock_destroy( ) function may fail if: [EBUSY] The implementation has detected an attempt to destroy the object referenced by rwlock while it is locked. [EINVAL] The value specified by rwlock is invalid. Shall not return an error code of [EINTR]