On successful completion, pthread_mutex_setprioceiling() returns 0. Any other return value indicates that an error occurred.
If the following condition occurs, pthread_mutexatt_setprioceiling() fails and returns the corresponding value.
The option _POSIX_THREAD_PRIO_PROTECT is not defined and the implementation does not support the function.
If any of the following conditions occurs, pthread_mutex_setprioceiling() might fail and return the corresponding value.
The priority requested by prioceiling is out of range.
The value specified by mutex does not refer to a currently existing mutex.
The implementation does not support the priority ceiling protocol for mutexes.
The caller does not have the privilege to perform the operation.