The function int pthread_condattr_destroy(pthread_condattr_t *attr); shall destroy a condition variable attributes object; the object becomes, in effect, uninitialized. An implementation may cause pthread_condattr_destroy() to set the object referenced by attr to an invalid value. A destroyed attr attributes object can be reinitialized using pthread_condattr_init(); the results of otherwise referencing the object after it has been destroyed are undefined. If successful, it shall return zero; The pthread_condattr_destroy() function may fail if: [EINVAL] The value specified by attr is invalid.