1PTHREAD_MUTEXATTR_GETPROTOCOPLO(S3IPX)Programmer'sPMTaHnRuEaAlD_MUTEXATTR_GETPROTOCOL(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_getprotocol, pthread_mutexattr_setprotocol — get and
14 set the protocol attribute of the mutex attributes object (REALTIME
15 THREADS)
16
18 #include <pthread.h>
19 int pthread_mutexattr_getprotocol(const pthread_mutexattr_t
21 *restrict attr, int *restrict protocol);
22 int pthread_mutexattr_setprotocol(pthread_mutexattr_t *attr,
23 int protocol);
24
26 The pthread_mutexattr_getprotocol() and pthread_mutexattr_setprotocol()
27 functions, respectively, shall get and set the protocol attribute of a
28 mutex attributes object pointed to by attr which was previously created
29 by the function pthread_mutexattr_init().
30 The protocol attribute defines the protocol to be followed in utilizing
32 mutexes. The value of protocol may be one of:
33 PTHREAD_PRIO_INHERIT
35 PTHREAD_PRIO_NONE
36 PTHREAD_PRIO_PROTECT
37 which are defined in the <pthread.h> header. The default value of the
39 attribute shall be PTHREAD_PRIO_NONE.
40 When a thread owns a mutex with the PTHREAD_PRIO_NONE protocol
42 attribute, its priority and scheduling shall not be affected by its
43 mutex ownership.
44 When a thread is blocking higher priority threads because of owning one
46 or more robust mutexes with the PTHREAD_PRIO_INHERIT protocol
47 attribute, it shall execute at the higher of its priority or the prior‐
48 ity of the highest priority thread waiting on any of the robust mutexes
49 owned by this thread and initialized with this protocol.
50 When a thread is blocking higher priority threads because of owning one
52 or more non-robust mutexes with the PTHREAD_PRIO_INHERIT protocol
53 attribute, it shall execute at the higher of its priority or the prior‐
54 ity of the highest priority thread waiting on any of the non-robust
55 mutexes owned by this thread and initialized with this protocol.
56 When a thread owns one or more robust mutexes initialized with the
58 PTHREAD_PRIO_PROTECT protocol, it shall execute at the higher of its
59 priority or the highest of the priority ceilings of all the robust
60 mutexes owned by this thread and initialized with this attribute,
61 regardless of whether other threads are blocked on any of these robust
62 mutexes or not.
63 When a thread owns one or more non-robust mutexes initialized with the
65 PTHREAD_PRIO_PROTECT protocol, it shall execute at the higher of its
66 priority or the highest of the priority ceilings of all the non-robust
67 mutexes owned by this thread and initialized with this attribute,
68 regardless of whether other threads are blocked on any of these non-
69 robust mutexes or not.
70 While a thread is holding a mutex which has been initialized with the
72 PTHREAD_PRIO_INHERIT or PTHREAD_PRIO_PROTECT protocol attributes, it
73 shall not be subject to being moved to the tail of the scheduling queue
74 at its priority in the event that its original priority is changed,
75 such as by a call to sched_setparam(). Likewise, when a thread unlocks
76 a mutex that has been initialized with the PTHREAD_PRIO_INHERIT or
77 PTHREAD_PRIO_PROTECT protocol attributes, it shall not be subject to
78 being moved to the tail of the scheduling queue at its priority in the
79 event that its original priority is changed.
80 If a thread simultaneously owns several mutexes initialized with dif‐
82 ferent protocols, it shall execute at the highest of the priorities
83 that it would have obtained by each of these protocols.
84 When a thread makes a call to pthread_mutex_lock(), the mutex was ini‐
86 tialized with the protocol attribute having the value
87 PTHREAD_PRIO_INHERIT, when the calling thread is blocked because the
88 mutex is owned by another thread, that owner thread shall inherit the
89 priority level of the calling thread as long as it continues to own the
90 mutex. The implementation shall update its execution priority to the
91 maximum of its assigned priority and all its inherited priorities.
92 Furthermore, if this owner thread itself becomes blocked on another
93 mutex with the protocol attribute having the value
94 PTHREAD_PRIO_INHERIT, the same priority inheritance effect shall be
95 propagated to this other owner thread, in a recursive manner.
96 The behavior is undefined if the value specified by the attr argument
98 to pthread_mutexattr_getprotocol() or pthread_mutexattr_setprotocol()
99 does not refer to an initialized mutex attributes object.
100
102 Upon successful completion, the pthread_mutexattr_getprotocol() and
103 pthread_mutexattr_setprotocol() functions shall return zero; otherwise,
104 an error number shall be returned to indicate the error.
105
107 The pthread_mutexattr_setprotocol() function shall fail if:
108 ENOTSUP
110 The value specified by protocol is an unsupported value.
111 The pthread_mutexattr_getprotocol() and pthread_mutexattr_setprotocol()
113 functions may fail if:
114 EINVAL The value specified by protocol is invalid.
116 EPERM The caller does not have the privilege to perform the operation.
118 These functions shall not return an error code of [EINTR].
120 The following sections are informative.
122
124 None.
125
127 None.
128
130 If an implementation detects that the value specified by the attr argu‐
131 ment to pthread_mutexattr_getprotocol() or pthread_mutexattr_setproto‐
132 col() does not refer to an initialized mutex attributes object, it is
133 recommended that the function should fail and report an [EINVAL] error.
134
136 None.
137
139 pthread_cond_destroy(), pthread_create(), pthread_mutex_destroy()
140 The Base Definitions volume of POSIX.1‐2008, <pthread.h>
142
144 Portions of this text are reprinted and reproduced in electronic form
145 from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
146 -- Portable Operating System Interface (POSIX), The Open Group Base
147 Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
148 cal and Electronics Engineers, Inc and The Open Group. (This is
149 POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the
150 event of any discrepancy between this version and the original IEEE and
151 The Open Group Standard, the original IEEE and The Open Group Standard
152 is the referee document. The original Standard can be obtained online
153 at http://www.unix.org/online.html .
154 Any typographical or formatting errors that appear in this page are
156 most likely to have been introduced during the conversion of the source
157 files to man page format. To report such errors, see https://www.ker‐
158 nel.org/doc/man-pages/reporting_bugs.html .
159IEEE/The Open Group 2013 PTHREAD_MUTEXATTR_GETPROTOCOL(3P)