pthread_mutex_getprioceiling

       set the priority ceiling of a mutex (REALTIME THREADS)

SYNOPSIS
       #include <pthread.h>

       int pthread_mutex_getprioceiling(const pthread_mutex_t *restrict mutex,
              int *restrict prioceiling);
       int pthread_mutex_setprioceiling(pthread_mutex_t *restrict mutex,
              int prioceiling, int *restrict old_ceiling);


DESCRIPTION
       The pthread_mutex_getprioceiling() function shall  return  the  current
       priority ceiling of the mutex.

       The pthread_mutex_setprioceiling() function shall either lock the mutex
       if it is unlocked, or block until it can successfully lock  the  mutex,
       then  it  shall  change  the  mutex's  priority ceiling and release the
       mutex. When the change is successful, the previous value of the  prior-
       ity  ceiling  shall  be returned in old_ceiling. The process of locking
       the mutex need not adhere to the priority protect protocol.

       If the pthread_mutex_setprioceiling() function fails, the mutex  prior-
       ity ceiling shall not be changed.

RETURN VALUE
       If      successful,      the     pthread_mutex_getprioceiling()     and
       pthread_mutex_setprioceiling() functions shall return zero;  otherwise,
       an error number shall be returned to indicate the error.

ERRORS
       The  pthread_mutex_getprioceiling()  and pthread_mutex_setprioceiling()
       functions may fail if:

       EINVAL The priority requested by prioceiling is out of range.

       EINVAL The value specified by mutex  does  not  refer  to  a  currently
              existing mutex.

       EPERM  The caller does not have the privilege to perform the operation.


       These functions shall not return an error code of [EINTR].

       The following sections are informative.

EXAMPLES
       None.

APPLICATION USAGE
       None.

RATIONALE
       None.
       --  Portable  Operating  System  Interface (POSIX), The Open Group Base
       Specifications Issue 6, Copyright (C) 2001-2003  by  the  Institute  of
       Electrical  and  Electronics  Engineers, Inc and The Open Group. In the
       event of any discrepancy between this version and the original IEEE and
       The  Open Group Standard, the original IEEE and The Open Group Standard
       is the referee document. The original Standard can be  obtained  online
       at http://www.opengroup.org/unix/online.html .



IEEE/The Open Group                  2003      PTHREAD_MUTEX_GETPRIOCEILING(P)