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PTHREAD_MUTEXATTR_GETROBUST(3P) Programmer's ManualD_MUTEXATTR_GETROBUST(3P)
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.
pthread_mutexattr_getrobust, pthread_mutexattr_setrobust — get and
set the mutex robust attribute
#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);
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.
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.
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.
None.
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.
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.
None.
pthread_mutex_consistent(3p), pthread_mutex_destroy(3p),
pthread_mutex_lock(3p)
The Base Definitions volume of POSIX.1‐2008, pthread.h(0p)
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)
Pages that refer to this page: pthread.h(0p), pthread_mutexattr_setrobust(3p), pthread_mutex_consistent(3p), pthread_mutex_destroy(3p), pthread_mutex_lock(3p)