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
12 pthread_mutexattr_getrobust, pthread_mutexattr_setrobust — get and set
13 the mutex robust attribute
14
16 #include <pthread.h>
17 int pthread_mutexattr_getrobust(const pthread_mutexattr_t *restrict
19 attr, int *restrict robust);
20 int pthread_mutexattr_setrobust(pthread_mutexattr_t *attr,
21 int robust);
22
24 The pthread_mutexattr_getrobust() and pthread_mutexattr_setrobust()
25 functions, respectively, shall get and set the mutex robust attribute.
26 This attribute is set in the robust parameter. Valid values for robust
27 include:
28 PTHREAD_MUTEX_STALLED
30 No special actions are taken if the owner of the mutex is termi‐
31 nated while holding the mutex lock. This can lead to deadlocks if
32 no other thread can unlock the mutex.
33 This is the default value.
34 PTHREAD_MUTEX_ROBUST
36 If the process containing the owning thread of a robust mutex
37 terminates while holding the mutex lock, the next thread that
38 acquires the mutex shall be notified about the termination by the
39 return value [EOWNERDEAD] from the locking function. If the own‐
40 ing thread of a robust mutex terminates while holding the mutex
41 lock, the next thread that attempts to acquire the mutex may be
42 notified about the termination by the return value [EOWNERDEAD].
43 The notified thread can then attempt to make the state protected
44 by the mutex consistent again, and if successful can mark the
45 mutex state as consistent by calling pthread_mutex_consistent().
46 After a subsequent successful call to pthread_mutex_unlock(), the
47 mutex lock shall be released and can be used normally by other
48 threads. If the mutex is unlocked without a call to
49 pthread_mutex_consistent(), it shall be in a permanently unusable
50 state and all attempts to lock the mutex shall fail with the
51 error [ENOTRECOVERABLE]. The only permissible operation on such
52 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.1‐2017, <pthread.h>
109
111 Portions of this text are reprinted and reproduced in electronic form
112 from IEEE Std 1003.1-2017, Standard for Information Technology -- Por‐
113 table Operating System Interface (POSIX), The Open Group Base Specifi‐
114 cations Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of
115 Electrical and Electronics Engineers, Inc and The Open Group. In the
116 event of any discrepancy between this version and the original IEEE and
117 The Open Group Standard, the original IEEE and The Open Group Standard
118 is the referee document. The original Standard can be obtained online
119 at http://www.opengroup.org/unix/online.html .
120 Any typographical or formatting errors that appear in this page are
122 most likely to have been introduced during the conversion of the source
123 files to man page format. To report such errors, see https://www.ker‐
124 nel.org/doc/man-pages/reporting_bugs.html .
125IEEE/The Open Group 2017 PTHREAD_MUTEXATTR_GETROBUST(3P)