pthread_spin_destroy( ) function shall destroy the spin lock referenced by lock and release any resources used by the lock. Upon successful completion, these functions shall return zero; otherwise, an error number shall be returned to indicate the error. The functions may fail if: [EBUSY] The implementation has detected an attempt to initialize or destroy a spin lock while it is in use (for example, while being used in a pthread_spin_lock( ) call) by another thread. [EINVAL] The value specified by lock is invalid. These functions shall not return an error code of EINTR.