On successful completion, pthread_mutex_setprioceiling() returns 0. Any other return value indicates that an error occurred.
If any of the following conditions occurs, pthread_mutex_setprioceiling() might fail and return the corresponding value.
EINVAL
Description:The priority requested by prioceiling is out of range.
EINVAL
Description:The mutex was not initialized with its protocol attribute having the value of THREAD_PRIO_PROTECT.
EPERM
Description:The caller does not have the privilege to perform the operation.