DESCRIPTION
 The  pthread_spin_lock function will acquire  lock if it is not currently owned by another thread. If the lock cannot be acquired immediately, it will spin attempting to acquire the lock (it will not sleep) until it becomes available.  The  pthread_spin_trylock function is the same as  pthread_spin_lock except that if it cannot acquire  lock immediately it will return with an error. 
 The  pthread_spin_unlock function will release  lock, which must have been previously locked by a call to  pthread_spin_lock or  pthread_spin_trylock.  
RETURN VALUES
 If successful, all these functions will return zero. Otherwise, an error number will be returned to indicate the error.  None of these functions will return  EINTR.  
ERRORS
 The  pthread_spin_lock,  pthread_spin_trylock and  pthread_spin_unlock functions will fail if: