be6116fdfc
The descriptions may be more elaborated of course, but this is a good step at starting providing any useful information in our man page, at all. Reviewed by: markj Sponsored by: The FreeBSD Foundation MFC after: 3 days Differential revision: https://reviews.freebsd.org/D32243
346 lines
9.0 KiB
Groff
346 lines
9.0 KiB
Groff
.\" Copyright (C) 2000 Jason Evans <jasone@FreeBSD.org>.
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.\" Copyright (c) 2021 The FreeBSD Foundation, Inc.
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.\" All rights reserved.
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.\"
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.\" Part of this documentation was written by
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.\" Konstantin Belousov <kib@FreeBSD.org> under sponsorship
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.\" from the FreeBSD Foundation.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice(s), this list of conditions and the following disclaimer as
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.\" the first lines of this file unmodified other than the possible
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.\" addition of one or more copyright notices.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice(s), this list of conditions and the following disclaimer in
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.\" the documentation and/or other materials provided with the
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.\" distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
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.\" EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE
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.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
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.\" BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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.\" WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
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.\" OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
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.\" EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.Dd October 1, 2021
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.Dt PTHREAD_MUTEXATTR 3
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.Os
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.Sh NAME
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.Nm pthread_mutexattr_init ,
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.Nm pthread_mutexattr_destroy ,
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.Nm pthread_mutexattr_setprioceiling ,
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.Nm pthread_mutexattr_getprioceiling ,
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.Nm pthread_mutexattr_setprotocol ,
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.Nm pthread_mutexattr_getprotocol ,
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.Nm pthread_mutexattr_setpshared ,
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.Nm pthread_mutexattr_getpshared ,
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.Nm pthread_mutexattr_setrobust ,
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.Nm pthread_mutexattr_getrobust ,
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.Nm pthread_mutexattr_settype ,
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.Nm pthread_mutexattr_gettype
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.Nd mutex attribute operations
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.Sh LIBRARY
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.Lb libpthread
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.Sh SYNOPSIS
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.In pthread.h
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.Ft int
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.Fn pthread_mutexattr_init "pthread_mutexattr_t *attr"
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.Ft int
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.Fn pthread_mutexattr_destroy "pthread_mutexattr_t *attr"
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.Ft int
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.Fo pthread_mutexattr_setprioceiling
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.Fa "pthread_mutexattr_t *attr" "int prioceiling"
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.Fc
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.Ft int
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.Fo pthread_mutexattr_getprioceiling
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.Fa "const pthread_mutexattr_t *attr" "int *prioceiling"
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.Fc
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.Ft int
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.Fn pthread_mutexattr_setprotocol "pthread_mutexattr_t *attr" "int protocol"
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.Ft int
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.Fo pthread_mutexattr_getprotocol
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.Fa "const pthread_mutexattr_t *restrict attr" "int *restrict protocol"
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.Fc
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.Ft int
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.Fo pthread_mutexattr_setpshared
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.Fa "pthread_mutexattr_t *attr" "int shared"
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.Fc
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.Ft int
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.Fo pthread_mutexattr_getpshared
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.Fa "const pthread_mutexattr_t *attr" "int *shared"
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.Fc
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.Ft int
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.Fn pthread_mutexattr_setrobust "pthread_mutexattr_t *attr" "int robust"
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.Ft int
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.Fn pthread_mutexattr_getrobust "pthread_mutexattr_t *attr" "int *robust"
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.Ft int
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.Fn pthread_mutexattr_settype "pthread_mutexattr_t *attr" "int type"
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.Ft int
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.Fo pthread_mutexattr_gettype
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.Fa "const pthread_mutexattr_t *restrict attr" "int *restrict type"
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.Fc
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.Sh DESCRIPTION
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Mutex attributes are used to specify parameters to
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.Fn pthread_mutex_init .
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One attribute object can be used in multiple calls to
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.Fn pthread_mutex_init ,
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with or without modifications between calls.
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.Pp
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The
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.Fn pthread_mutexattr_init
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function initializes
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.Fa attr
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with all the default mutex attributes.
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.Pp
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The
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.Fn pthread_mutexattr_destroy
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function destroys
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.Fa attr .
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.Pp
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The
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.Fn pthread_mutexattr_setprioceiling
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function sets the priority ceiling for the mutex, used
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by threads executed under the
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.Dv PTHREAD_PRIO_PROTECT
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protocol.
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.Pp
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The
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.Fn pthread_mutexattr_setprotocol
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function specifies the protocol to be followed in utilizing mutexes.
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The
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.Fa protocol
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argument can take one of the following values:
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.Bl -tag -width PTHREAD_PRIO_PROTECT
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.It PTHREAD_PRIO_NONE
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Priority and scheduling of the thread owning this mutex is not
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affected by its mutex ownership.
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.It PTHREAD_PRIO_INHERIT
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Request priority-inheritance protocol, where the thread owning the mutex
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is executed at the highest priority among priorities of all threads waiting
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on any mutex owned by this thread.
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.It PTHREAD_PRIO_PROTECT
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Request priority-inheritance protocol, where the thread owning the mutex
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is executed at highest priority among priorities or priority ceilings of
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all threads waiting on any mutex owned by this thread.
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.El
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.Pp
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The
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.Fn pthread_mutexattr_setrobust
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function specifies robustness attribute of the mutex.
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Possible values for the
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.Fa robust
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argument are
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.Bl -tag -width PTHREAD_MUTEX_STALLED
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.It PTHREAD_MUTEX_STALLED
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No special actions are taken if the thread owning the mutex is terminated
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without unlocking the mutex lock.
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This can lead to deadlocks if no other thread can unlock the mutex.
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This is the default value.
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.It PTHREAD_MUTEX_ROBUST
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If the process containing the owning thread of a robust mutex, or owning
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thread, terminates while holding the mutex lock, the next thread that
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acquires the mutex is notified about the termination
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by the return value
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.Ev EOWNERDEAD
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from the locking function.
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Then, either
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.Xr pthread_mutex_consistent 3
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can be used to repair the mutex lock state, or
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.Xr pthread_mutex_unlock 3
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can unlock the mutex lock but also put it an unusable state,
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where all further attempts to acquire it result in the
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.Ev ENOTRECOVERABLE
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error.
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.El
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.Pp
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The
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.Fn pthread_mutexattr_settype
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function sets the type of the mutex.
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The type affects the behavior of calls which lock and unlock the mutex.
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The possible values for the
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.Fa type
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argument are
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.Bl -tag -width PTHREAD_MUTEX_ERRORCHECK
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.It PTHREAD_MUTEX_NORMAL
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Both recursive locking, and unlocking when the lock is not owned by the current
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thread, cause an error to be returned from the corresponding functions.
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This matches
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.Dv PTHREAD_MUTEX_ERRORCHECK
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but somewhat contradicts the behavior mandated by POSIX.
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.It PTHREAD_MUTEX_ERRORCHECK
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Both recursive locking, and unlocking when the lock is not owned by the current
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thread, cause an error returned from the corresponding functions.
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.It PTHREAD_MUTEX_RECURSIVE
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Recursive locking is allowed.
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Attempt to unlock when current thread is not an owner of the lock causes
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an error to be returned.
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.It PTHREAD_MUTEX_DEFAULT
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The
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.Fx
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implementation maps this type to
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.Dv PTHREAD_MUTEX_ERRORCHECK
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type.
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.El
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.Pp
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The
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.Fn pthread_mutexattr_get*
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functions copy the value of the attribute that corresponds to each function name
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to the location pointed to by the second function parameter.
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.Sh RETURN VALUES
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If successful, these functions return 0.
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Otherwise, an error number is returned to indicate the error.
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.Sh ERRORS
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The
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.Fn pthread_mutexattr_init
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function will fail if:
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.Bl -tag -width Er
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.It Bq Er ENOMEM
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Out of memory.
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.El
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.Pp
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The
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.Fn pthread_mutexattr_destroy
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function will fail if:
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.Bl -tag -width Er
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.It Bq Er EINVAL
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Invalid value for
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.Fa attr .
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.El
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.Pp
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The
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.Fn pthread_mutexattr_setprioceiling
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function will fail if:
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.Bl -tag -width Er
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.It Bq Er EINVAL
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Invalid value for
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.Fa attr ,
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or invalid value for
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.Fa prioceiling .
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.El
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.Pp
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The
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.Fn pthread_mutexattr_getprioceiling
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function will fail if:
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.Bl -tag -width Er
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.It Bq Er EINVAL
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Invalid value for
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.Fa attr .
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.El
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.Pp
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The
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.Fn pthread_mutexattr_setprotocol
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function will fail if:
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.Bl -tag -width Er
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.It Bq Er EINVAL
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Invalid value for
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.Fa attr ,
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or invalid value for
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.Fa protocol .
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.El
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.Pp
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The
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.Fn pthread_mutexattr_getprotocol
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function will fail if:
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.Bl -tag -width Er
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.It Bq Er EINVAL
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Invalid value for
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.Fa attr .
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.El
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.Pp
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The
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.Fn pthread_mutexattr_setpshared
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function will fail if:
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.Bl -tag -width Er
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.It Bq Er EINVAL
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Invalid value for
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.Fa attr ,
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or invalid value for
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.Fa shared .
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.El
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.Pp
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The
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.Fn pthread_mutexattr_getpshared
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function will fail if:
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.Bl -tag -width Er
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.It Bq Er EINVAL
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Invalid value for
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.Fa attr .
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.El
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.Pp
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The
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.Fn pthread_mutexattr_settype
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function will fail if:
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.Bl -tag -width Er
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.It Bq Er EINVAL
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Invalid value for
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.Fa attr ,
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or invalid value for
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.Fa type .
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.El
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.Pp
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The
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.Fn pthread_mutexattr_gettype
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function will fail if:
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.Bl -tag -width Er
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.It Bq Er EINVAL
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Invalid value for
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.Fa attr .
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.El
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.Pp
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The
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.Fn pthread_mutexattr_setrobust
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function will fail if:
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.Bl -tag -width Er
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.It Bq Er EINVAL
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Invalid value for
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.Fa attr ,
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or invalid value for
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.Fa robust .
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.El
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.Pp
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The
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.Fn pthread_mutexattr_getrobust
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function will fail if:
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.Bl -tag -width Er
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.It Bq Er EINVAL
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Invalid value for
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.Fa attr .
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.El
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.Sh SEE ALSO
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.Xr pthread_mutex_init 3
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.Sh STANDARDS
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The
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.Fn pthread_mutexattr_init
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and
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.Fn pthread_mutexattr_destroy
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functions conform to
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.St -p1003.1-96
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.Pp
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The
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.Fn pthread_mutexattr_setprioceiling ,
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.Fn pthread_mutexattr_getprioceiling ,
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.Fn pthread_mutexattr_setprotocol ,
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.Fn pthread_mutexattr_getprotocol ,
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.Fn pthread_mutexattr_setpshared ,
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.Fn pthread_mutexattr_getpshared ,
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.Fn pthread_mutexattr_settype ,
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and
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.Fn pthread_mutexattr_gettype
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functions conform to
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.St -susv2 .
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The
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.Fn pthread_mutexattr_setrobust
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and
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.Fn pthread_mutexattr_getrobust
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functions conform to
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.St -susv4 .
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