1PTHREAD_MUTEXATTR_GETROBUST(P3OPS)IX Programmer's MaPnTuHaRlEAD_MUTEXATTR_GETROBUST(3P)
2
6 This manual page is part of the POSIX Programmer's Manual. The Linux
7 implementation of this interface may differ (consult the corresponding
8 Linux manual page for details of Linux behavior), or the interface may
9 not be implemented on Linux.
10
13 pthread_mutexattr_getrobust, pthread_mutexattr_setrobust — get and set
14 the mutex robust attribute
15
17 #include <pthread.h>
18 int pthread_mutexattr_getrobust(const pthread_mutexattr_t *restrict
20 attr, int *restrict robust);
21 int pthread_mutexattr_setrobust(pthread_mutexattr_t *attr,
22 int robust);
23
25 The pthread_mutexattr_getrobust() and pthread_mutexattr_setrobust()
26 functions, respectively, shall get and set the mutex robust attribute.
27 This attribute is set in the robust parameter. Valid values for robust
28 include:
29 PTHREAD_MUTEX_STALLED
31 No special actions are taken if the owner of the mutex is termi‐
32 nated while holding the mutex lock. This can lead to deadlocks if
33 no other thread can unlock the mutex.
34 This is the default value.
35 PTHREAD_MUTEX_ROBUST
37 If the process containing the owning thread of a robust mutex
38 terminates while holding the mutex lock, the next thread that
39 acquires the mutex shall be notified about the termination by the
40 return value [EOWNERDEAD] from the locking function. If the own‐
41 ing thread of a robust mutex terminates while holding the mutex
42 lock, the next thread that acquires the mutex may be notified
43 about the termination by the return value [EOWNERDEAD]. The
44 notified thread can then attempt to mark the state protected by
45 the mutex as consistent again by a call to pthread_mutex_consis‐
46 tent(). After a subsequent successful call to
47 pthread_mutex_unlock(), the mutex lock shall be released and can
48 be used normally by other threads. If the mutex is unlocked with‐
49 out a call to pthread_mutex_consistent(), it shall be in a perma‐
50 nently unusable state and all attempts to lock the mutex shall
51 fail with the error [ENOTRECOVERABLE]. The only permissible
52 operation on such a mutex is pthread_mutex_destroy().
53 The behavior is undefined if the value specified by the attr argument
55 to pthread_mutexattr_getrobust() or pthread_mutexattr_setrobust() does
56 not refer to an initialized mutex attributes object.
57
59 Upon successful completion, the pthread_mutexattr_getrobust() function
60 shall return zero and store the value of the robust attribute of attr
61 into the object referenced by the robust parameter. Otherwise, an error
62 value shall be returned to indicate the error. If successful, the
63 pthread_mutexattr_setrobust() function shall return zero; otherwise, an
64 error number shall be returned to indicate the error.
65
67 The pthread_mutexattr_setrobust() function shall fail if:
68 EINVAL The value of robust is invalid.
70 These functions shall not return an error code of [EINTR].
72 The following sections are informative.
74
76 None.
77
79 The actions required to make the state protected by the mutex consis‐
80 tent again are solely dependent on the application. If it is not possi‐
81 ble to make the state of a mutex consistent, robust mutexes can be used
82 to notify this situation by calling pthread_mutex_unlock() without a
83 prior call to pthread_mutex_consistent().
84 If the state is declared inconsistent by calling pthread_mutex_unlock()
86 without a prior call to pthread_mutex_consistent(), a possible approach
87 could be to destroy the mutex and then reinitialize it. However, it
88 should be noted that this is possible only in certain situations where
89 the state protected by the mutex has to be reinitialized and coordina‐
90 tion achieved with other threads blocked on the mutex, because other‐
91 wise a call to a locking function with a reference to a mutex object
92 invalidated by a call to pthread_mutex_destroy() results in undefined
93 behavior.
94
96 If an implementation detects that the value specified by the attr argu‐
97 ment to pthread_mutexattr_getrobust() or pthread_mutexattr_setrobust()
98 does not refer to an initialized mutex attributes object, it is recom‐
99 mended that the function should fail and report an [EINVAL] error.
100
102 None.
103
105 pthread_mutex_consistent(), pthread_mutex_destroy(),
106 pthread_mutex_lock()
107 The Base Definitions volume of POSIX.1‐2008, <pthread.h>
109
111 Portions of this text are reprinted and reproduced in electronic form
112 from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
113 -- Portable Operating System Interface (POSIX), The Open Group Base
114 Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
115 cal and Electronics Engineers, Inc and The Open Group. (This is
116 POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the
117 event of any discrepancy between this version and the original IEEE and
118 The Open Group Standard, the original IEEE and The Open Group Standard
119 is the referee document. The original Standard can be obtained online
120 at http://www.unix.org/online.html .
121 Any typographical or formatting errors that appear in this page are
123 most likely to have been introduced during the conversion of the source
124 files to man page format. To report such errors, see https://www.ker‐
125 nel.org/doc/man-pages/reporting_bugs.html .
126IEEE/The Open Group 2013 PTHREAD_MUTEXATTR_GETROBUST(3P)