PROLOG

       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of
       this interface may differ (consult the corresponding Linux  manual  page  for  details  of
       Linux behavior), or the interface may not be implemented on Linux.

NAME

       pthread_mutex_getprioceiling,  pthread_mutex_setprioceiling  —  get  and  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  attempt to lock the mutex as if by a
       call to pthread_mutex_lock(), except that the process of locking the mutex need not adhere
       to  the  priority  protect  protocol.  On  acquiring the mutex it shall change the mutex's
       priority ceiling and then release the mutex as if by  a  call  to  pthread_mutex_unlock().
       When  the  change  is  successful,  the  previous  value  of the priority ceiling shall be
       returned in old_ceiling.

       If the pthread_mutex_setprioceiling() function fails, the mutex priority 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

       These functions shall fail if:

       EINVAL The protocol attribute of mutex is PTHREAD_PRIO_NONE.

       EPERM  The implementation requires appropriate privileges to perform the operation and the
              caller does not have appropriate privileges.

       The pthread_mutex_setprioceiling() function shall fail if:

       EAGAIN The mutex could not be acquired because the maximum number of recursive  locks  for
              mutex has been exceeded.

       EDEADLK
              The  mutex type is PTHREAD_MUTEX_ERRORCHECK and the current thread already owns the
              mutex.

       EINVAL The  mutex  was  created   with   the   protocol   attribute   having   the   value
              PTHREAD_PRIO_PROTECT  and  the calling thread's priority is higher than the mutex's
              current priority ceiling, and the implementation adheres to  the  priority  protect
              protocol in the process of locking the mutex.

       ENOTRECOVERABLE
              The  mutex  is  a  robust  mutex  and  the  state  protected  by  the  mutex is not
              recoverable.

       EOWNERDEAD
              The mutex is a robust mutex and the process containing the previous  owning  thread
              terminated  while  holding  the mutex lock. The mutex lock shall be acquired by the
              calling thread and it is up to the new owner to  make  the  state  consistent  (see
              pthread_mutex_lock()).

       The pthread_mutex_setprioceiling() function may fail if:

       EDEADLK
              A deadlock condition was detected.

       EINVAL The priority requested by prioceiling is out of range.

       EOWNERDEAD
              The mutex is a robust mutex and the previous owning thread terminated while holding
              the mutex lock. The mutex lock shall be acquired by the calling thread and it is up
              to the new owner to make the state consistent (see pthread_mutex_lock()).

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

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       None.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       pthread_mutex_destroy(), pthread_mutex_lock(), pthread_mutex_timedlock()

       The Base Definitions volume of POSIX.1‐2008, <pthread.h>

COPYRIGHT

       Portions  of  this  text  are  reprinted  and  reproduced in electronic form from IEEE Std
       1003.1, 2013 Edition, Standard for Information Technology  --  Portable  Operating  System
       Interface  (POSIX),  The Open Group Base Specifications Issue 7, Copyright (C) 2013 by the
       Institute of Electrical and Electronics Engineers, Inc  and  The  Open  Group.   (This  is
       POSIX.1-2008  with  the  2013  Technical  Corrigendum  1  applied.)  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.unix.org/online.html .

       Any typographical or formatting errors that appear in this page are most  likely  to  have
       been  introduced  during  the conversion of the source files to man page format. To report
       such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .