PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT

PTHREAD_MUTEXATTR_GETROBUST(3P) Programmer's ManualD_MUTEXATTR_GETROBUST(3P)

PROLOG         top

       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         top

       pthread_mutexattr_getrobust, pthread_mutexattr_setrobust — get and
       set the mutex robust attribute

SYNOPSIS         top

       #include <pthread.h>

       int pthread_mutexattr_getrobust(const pthread_mutexattr_t *restrict
           attr, int *restrict robust);
       int pthread_mutexattr_setrobust(pthread_mutexattr_t *attr,
           int robust);

DESCRIPTION         top

       The pthread_mutexattr_getrobust() and pthread_mutexattr_setrobust()
       functions, respectively, shall get and set the mutex robust
       attribute. This attribute is set in the robust parameter. Valid
       values for robust include:

       PTHREAD_MUTEX_STALLED
             No special actions are taken if the owner of the mutex is
             terminated while holding the mutex lock. This can lead to
             deadlocks if no other thread can unlock the mutex.
             This is the default value.

       PTHREAD_MUTEX_ROBUST
             If the process containing the owning thread of a robust mutex
             terminates while holding the mutex lock, the next thread that
             acquires the mutex shall be notified about the termination by
             the return value [EOWNERDEAD] from the locking function. If the
             owning thread of a robust mutex terminates while holding the
             mutex lock, the next thread that acquires the mutex may be
             notified about the termination by the return value
             [EOWNERDEAD].  The notified thread can then attempt to mark the
             state protected by the mutex as consistent again by a call to
             pthread_mutex_consistent().  After a subsequent successful call
             to pthread_mutex_unlock(), the mutex lock shall be released and
             can be used normally by other threads. If the mutex is unlocked
             without a call to pthread_mutex_consistent(), it shall be in a
             permanently unusable state and all attempts to lock the mutex
             shall fail with the error [ENOTRECOVERABLE].  The only
             permissible operation on such a mutex is
             pthread_mutex_destroy().

       The behavior is undefined if the value specified by the attr argument
       to pthread_mutexattr_getrobust() or pthread_mutexattr_setrobust()
       does not refer to an initialized mutex attributes object.

RETURN VALUE         top

       Upon successful completion, the pthread_mutexattr_getrobust()
       function shall return zero and store the value of the robust
       attribute of attr into the object referenced by the robust parameter.
       Otherwise, an error value shall be returned to indicate the error. If
       successful, the pthread_mutexattr_setrobust() function shall return
       zero; otherwise, an error number shall be returned to indicate the
       error.

ERRORS         top

       The pthread_mutexattr_setrobust() function shall fail if:

       EINVAL The value of robust is invalid.

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

       The following sections are informative.

EXAMPLES         top

       None.

APPLICATION USAGE         top

       The actions required to make the state protected by the mutex
       consistent again are solely dependent on the application. If it is
       not possible to make the state of a mutex consistent, robust mutexes
       can be used to notify this situation by calling
       pthread_mutex_unlock() without a prior call to
       pthread_mutex_consistent().

       If the state is declared inconsistent by calling
       pthread_mutex_unlock() without a prior call to
       pthread_mutex_consistent(), a possible approach could be to destroy
       the mutex and then reinitialize it. However, it should be noted that
       this is possible only in certain situations where the state protected
       by the mutex has to be reinitialized and coordination achieved with
       other threads blocked on the mutex, because otherwise a call to a
       locking function with a reference to a mutex object invalidated by a
       call to pthread_mutex_destroy() results in undefined behavior.

RATIONALE         top

       If an implementation detects that the value specified by the attr
       argument to pthread_mutexattr_getrobust() or
       pthread_mutexattr_setrobust() does not refer to an initialized mutex
       attributes object, it is recommended that the function should fail
       and report an [EINVAL] error.

FUTURE DIRECTIONS         top

       None.

SEE ALSO         top

       pthread_mutex_consistent(3p), pthread_mutex_destroy(3p),
       pthread_mutex_lock(3p)

       The Base Definitions volume of POSIX.1‐2008, pthread.h(0p)

COPYRIGHT         top

       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 .

IEEE/The Open Group                 2013     PTHREAD_MUTEXATTR_GETROBUST(3P)