1PTHREAD_MUTEXATTR_GETPROTOCOPLO(S3IPX)Programmer'sPMTaHnRuEaAlD_MUTEXATTR_GETPROTOCOL(3P)
2
3
4
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_getprotocol, pthread_mutexattr_setprotocol — get and
13 set the protocol attribute of the mutex attributes object (REALTIME
14 THREADS)
15
17 #include <pthread.h>
18
19 int pthread_mutexattr_getprotocol(const pthread_mutexattr_t
20 *restrict attr, int *restrict protocol);
21 int pthread_mutexattr_setprotocol(pthread_mutexattr_t *attr,
22 int protocol);
23
25 The pthread_mutexattr_getprotocol() and pthread_mutexattr_setprotocol()
26 functions, respectively, shall get and set the protocol attribute of a
27 mutex attributes object pointed to by attr which was previously created
28 by the function pthread_mutexattr_init().
29
30 The protocol attribute defines the protocol to be followed in utilizing
31 mutexes. The value of protocol may be one of:
32
33 PTHREAD_PRIO_INHERIT
34 PTHREAD_PRIO_NONE
35 PTHREAD_PRIO_PROTECT
36
37 which are defined in the <pthread.h> header. The default value of the
38 attribute shall be PTHREAD_PRIO_NONE.
39
40 When a thread owns a mutex with the PTHREAD_PRIO_NONE protocol
41 attribute, its priority and scheduling shall not be affected by its
42 mutex ownership.
43
44 When a thread is blocking higher priority threads because of owning one
45 or more robust mutexes with the PTHREAD_PRIO_INHERIT protocol
46 attribute, it shall execute at the higher of its priority or the prior‐
47 ity of the highest priority thread waiting on any of the robust mutexes
48 owned by this thread and initialized with this protocol.
49
50 When a thread is blocking higher priority threads because of owning one
51 or more non-robust mutexes with the PTHREAD_PRIO_INHERIT protocol
52 attribute, it shall execute at the higher of its priority or the prior‐
53 ity of the highest priority thread waiting on any of the non-robust
54 mutexes owned by this thread and initialized with this protocol.
55
56 When a thread owns one or more robust mutexes initialized with the
57 PTHREAD_PRIO_PROTECT protocol, it shall execute at the higher of its
58 priority or the highest of the priority ceilings of all the robust
59 mutexes owned by this thread and initialized with this attribute,
60 regardless of whether other threads are blocked on any of these robust
61 mutexes or not.
62
63 When a thread owns one or more non-robust mutexes initialized with the
64 PTHREAD_PRIO_PROTECT protocol, it shall execute at the higher of its
65 priority or the highest of the priority ceilings of all the non-robust
66 mutexes owned by this thread and initialized with this attribute,
67 regardless of whether other threads are blocked on any of these non-
68 robust mutexes or not.
69
70 While a thread is holding a mutex which has been initialized with the
71 PTHREAD_PRIO_INHERIT or PTHREAD_PRIO_PROTECT protocol attributes, it
72 shall not be subject to being moved to the tail of the scheduling queue
73 at its priority in the event that its original priority is changed,
74 such as by a call to sched_setparam(). Likewise, when a thread unlocks
75 a mutex that has been initialized with the PTHREAD_PRIO_INHERIT or
76 PTHREAD_PRIO_PROTECT protocol attributes, it shall not be subject to
77 being moved to the tail of the scheduling queue at its priority in the
78 event that its original priority is changed.
79
80 If a thread simultaneously owns several mutexes initialized with dif‐
81 ferent protocols, it shall execute at the highest of the priorities
82 that it would have obtained by each of these protocols.
83
84 When a thread makes a call to pthread_mutex_lock(), the mutex was ini‐
85 tialized with the protocol attribute having the value
86 PTHREAD_PRIO_INHERIT, when the calling thread is blocked because the
87 mutex is owned by another thread, that owner thread shall inherit the
88 priority level of the calling thread as long as it continues to own the
89 mutex. The implementation shall update its execution priority to the
90 maximum of its assigned priority and all its inherited priorities.
91 Furthermore, if this owner thread itself becomes blocked on another
92 mutex with the protocol attribute having the value
93 PTHREAD_PRIO_INHERIT, the same priority inheritance effect shall be
94 propagated to this other owner thread, in a recursive manner.
95
96 The behavior is undefined if the value specified by the attr argument
97 to pthread_mutexattr_getprotocol() or pthread_mutexattr_setprotocol()
98 does not refer to an initialized mutex attributes object.
99
101 Upon successful completion, the pthread_mutexattr_getprotocol() and
102 pthread_mutexattr_setprotocol() functions shall return zero; otherwise,
103 an error number shall be returned to indicate the error.
104
106 The pthread_mutexattr_setprotocol() function shall fail if:
107
108 ENOTSUP
109 The value specified by protocol is an unsupported value.
110
111 The pthread_mutexattr_getprotocol() and pthread_mutexattr_setprotocol()
112 functions may fail if:
113
114 EINVAL The value specified by protocol is invalid.
115
116 EPERM The caller does not have the privilege to perform the operation.
117
118 These functions shall not return an error code of [EINTR].
119
120 The following sections are informative.
121
123 None.
124
126 None.
127
129 If an implementation detects that the value specified by the attr argu‐
130 ment to pthread_mutexattr_getprotocol() or pthread_mutexattr_setproto‐
131 col() does not refer to an initialized mutex attributes object, it is
132 recommended that the function should fail and report an [EINVAL] error.
133
135 None.
136
138 pthread_cond_destroy(), pthread_create(), pthread_mutex_destroy()
139
140 The Base Definitions volume of POSIX.1‐2017, <pthread.h>
141
143 Portions of this text are reprinted and reproduced in electronic form
144 from IEEE Std 1003.1-2017, Standard for Information Technology -- Por‐
145 table Operating System Interface (POSIX), The Open Group Base Specifi‐
146 cations Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of
147 Electrical and Electronics Engineers, Inc and The Open Group. In the
148 event of any discrepancy between this version and the original IEEE and
149 The Open Group Standard, the original IEEE and The Open Group Standard
150 is the referee document. The original Standard can be obtained online
151 at http://www.opengroup.org/unix/online.html .
152
153 Any typographical or formatting errors that appear in this page are
154 most likely to have been introduced during the conversion of the source
155 files to man page format. To report such errors, see https://www.ker‐
156 nel.org/doc/man-pages/reporting_bugs.html .
157
158
159
160IEEE/The Open Group 2017 PTHREAD_MUTEXATTR_GETPROTOCOL(3P)