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PTHREAD_MUTEXATTR_GETPROTOCOL(3P)rogrammer'sTManualMUTEXATTR_GETPROTOCOL(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_getprotocol, pthread_mutexattr_setprotocol — get
and set the protocol attribute of the mutex attributes object
(REALTIME THREADS)
#include <pthread.h>
int pthread_mutexattr_getprotocol(const pthread_mutexattr_t
*restrict attr, int *restrict protocol);
int pthread_mutexattr_setprotocol(pthread_mutexattr_t *attr,
int protocol);
The pthread_mutexattr_getprotocol() and
pthread_mutexattr_setprotocol() functions, respectively, shall get
and set the protocol attribute of a mutex attributes object pointed
to by attr which was previously created by the function
pthread_mutexattr_init().
The protocol attribute defines the protocol to be followed in
utilizing mutexes. The value of protocol may be one of:
PTHREAD_PRIO_INHERIT
PTHREAD_PRIO_NONE
PTHREAD_PRIO_PROTECT
which are defined in the <pthread.h> header. The default value of the
attribute shall be PTHREAD_PRIO_NONE.
When a thread owns a mutex with the PTHREAD_PRIO_NONE protocol
attribute, its priority and scheduling shall not be affected by its
mutex ownership.
When a thread is blocking higher priority threads because of owning
one or more robust mutexes with the PTHREAD_PRIO_INHERIT protocol
attribute, it shall execute at the higher of its priority or the
priority of the highest priority thread waiting on any of the robust
mutexes owned by this thread and initialized with this protocol.
When a thread is blocking higher priority threads because of owning
one or more non-robust mutexes with the PTHREAD_PRIO_INHERIT protocol
attribute, it shall execute at the higher of its priority or the
priority of the highest priority thread waiting on any of the non-
robust mutexes owned by this thread and initialized with this
protocol.
When a thread owns one or more robust mutexes initialized with the
PTHREAD_PRIO_PROTECT protocol, it shall execute at the higher of its
priority or the highest of the priority ceilings of all the robust
mutexes owned by this thread and initialized with this attribute,
regardless of whether other threads are blocked on any of these
robust mutexes or not.
When a thread owns one or more non-robust mutexes initialized with
the PTHREAD_PRIO_PROTECT protocol, it shall execute at the higher of
its priority or the highest of the priority ceilings of all the non-
robust mutexes owned by this thread and initialized with this
attribute, regardless of whether other threads are blocked on any of
these non-robust mutexes or not.
While a thread is holding a mutex which has been initialized with the
PTHREAD_PRIO_INHERIT or PTHREAD_PRIO_PROTECT protocol attributes, it
shall not be subject to being moved to the tail of the scheduling
queue at its priority in the event that its original priority is
changed, such as by a call to sched_setparam(). Likewise, when a
thread unlocks a mutex that has been initialized with the
PTHREAD_PRIO_INHERIT or PTHREAD_PRIO_PROTECT protocol attributes, it
shall not be subject to being moved to the tail of the scheduling
queue at its priority in the event that its original priority is
changed.
If a thread simultaneously owns several mutexes initialized with
different protocols, it shall execute at the highest of the
priorities that it would have obtained by each of these protocols.
When a thread makes a call to pthread_mutex_lock(), the mutex was
initialized with the protocol attribute having the value
PTHREAD_PRIO_INHERIT, when the calling thread is blocked because the
mutex is owned by another thread, that owner thread shall inherit the
priority level of the calling thread as long as it continues to own
the mutex. The implementation shall update its execution priority to
the maximum of its assigned priority and all its inherited
priorities. Furthermore, if this owner thread itself becomes blocked
on another mutex with the protocol attribute having the value
PTHREAD_PRIO_INHERIT, the same priority inheritance effect shall be
propagated to this other owner thread, in a recursive manner.
The behavior is undefined if the value specified by the attr argument
to pthread_mutexattr_getprotocol() or pthread_mutexattr_setprotocol()
does not refer to an initialized mutex attributes object.
Upon successful completion, the pthread_mutexattr_getprotocol() and
pthread_mutexattr_setprotocol() functions shall return zero;
otherwise, an error number shall be returned to indicate the error.
The pthread_mutexattr_setprotocol() function shall fail if:
ENOTSUP
The value specified by protocol is an unsupported value.
The pthread_mutexattr_getprotocol() and
pthread_mutexattr_setprotocol() functions may fail if:
EINVAL The value specified by protocol is invalid.
EPERM The caller does not have the privilege to perform the
operation.
These functions shall not return an error code of [EINTR].
The following sections are informative.
None.
None.
If an implementation detects that the value specified by the attr
argument to pthread_mutexattr_getprotocol() or
pthread_mutexattr_setprotocol() does not refer to an initialized
mutex attributes object, it is recommended that the function should
fail and report an [EINVAL] error.
None.
pthread_cond_destroy(3p), pthread_create(3p),
pthread_mutex_destroy(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_GETPROTOCOL(3P)
Pages that refer to this page: pthread.h(0p), pthread_mutexattr_setprotocol(3p)