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.1‐2017, <pthread.h>

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard
       for Information  Technology  --  Portable  Operating  System  Interface  (POSIX),  The  Open  Group  Base
       Specifications  Issue  7, 2018 Edition, Copyright (C) 2018 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 .

       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 .