249 lines
8.1 KiB
Groff
249 lines
8.1 KiB
Groff
.\" $NetBSD: pthread_mutexattr.3,v 1.9 2009/04/11 16:51:39 wiz Exp $
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.\"
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.\" Copyright (c) 2002 The NetBSD Foundation, Inc.
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.\" All rights reserved.
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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, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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.\" BE 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 BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" Copyright (C) 2000 Jason Evans <jasone@FreeBSD.org>.
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.\" All rights reserved.
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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: src/lib/libpthread/man/pthread_mutexattr.3,v 1.8 2002/09/16 19:29:29 mini Exp $
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.Dd January 30, 2003
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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_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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.\" .Fn pthread_mutexattr_setprioceiling "pthread_mutexattr_t *attr" "int prioceiling"
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.\" .Ft int
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.\" .Fn pthread_mutexattr_getprioceiling "pthread_mutexattr_t *attr" "int *prioceiling"
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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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.\" .Fn pthread_mutexattr_getprotocol "pthread_mutexattr_t *attr" "int *protocol"
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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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.Fn pthread_mutexattr_gettype "pthread_mutexattr_t * restrict attr" "int * restrict type"
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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_settype
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functions set the mutex type value of the attribute.
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Valid mutex types are:
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.Dv PTHREAD_MUTEX_NORMAL ,
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.Dv PTHREAD_MUTEX_ERRORCHECK ,
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.Dv PTHREAD_MUTEX_RECURSIVE ,
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and
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.Dv PTHREAD_MUTEX_DEFAULT .
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The default mutex type for
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.Fn pthread_mutexaddr_init
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is
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.Dv PTHREAD_MUTEX_DEFAULT .
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.Pp
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.Dv PTHREAD_MUTEX_NORMAL
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mutexes do not check for usage errors.
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.Dv PTHREAD_MUTEX_NORMAL
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mutexes will deadlock if reentered, and result in undefined behavior if a
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locked mutex is unlocked by another thread.
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Attempts to unlock an already unlocked
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.Dv PTHREAD_MUTEX_NORMAL
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mutex will result in undefined behavior.
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.Pp
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.Dv PTHREAD_MUTEX_ERRORCHECK
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mutexes do check for usage errors.
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If an attempt is made to relock a
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.Dv PTHREAD_MUTEX_ERRORCHECK
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mutex without first dropping the lock an error will be returned.
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If a thread attempts to unlock a
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.Dv PTHREAD_MUTEX_ERRORCHECK
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mutex that is locked by another thread, an error will be returned.
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If a thread attempts to unlock a
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.Dv PTHREAD_MUTEX_ERRORCHECK
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thread that is unlocked, an error will be
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returned.
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.Pp
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.Dv PTHREAD_MUTEX_RECURSIVE
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mutexes allow recursive locking.
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An attempt to relock a
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.Dv PTHREAD_MUTEX_RECURSIVE
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mutex that is already locked by the same thread succeeds.
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An equivalent number of
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.Xr pthread_mutex_unlock 3
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calls are needed before the mutex will wake another thread waiting
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on this lock.
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If a thread attempts to unlock a
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.Dv PTHREAD_MUTEX_RECURSIVE
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mutex that is locked by another thread, an error will be returned.
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If a thread attempts to unlock a
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.Dv PTHREAD_MUTEX_RECURSIVE
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thread that is unlocked, an error will be returned.
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.Pp
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.Dv PTHREAD_MUTEX_DEFAULT
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mutexes result in undefined behavior if reentered.
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Unlocking a
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.Dv PTHREAD_MUTEX_DEFAULT
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mutex locked by another thread will result in undefined behavior.
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Attempts to unlock an already unlocked
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.Dv PTHREAD_MUTEX_DEFAULT
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mutex will result in undefined behavior.
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.Pp
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.Fn pthread_mutexattr_gettype
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functions copy the type value of the attribute to the location
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pointed to by the second 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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.Fn pthread_mutexattr_init
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shall fail if:
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.Bl -tag -width Er
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.It Bq Er ENOMEM
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Insufficient memory exists to initialize the mutex attributes object.
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.El
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.Pp
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.Fn pthread_mutexattr_settype
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shall fail if:
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.Bl -tag -width Er
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.It Bq Er EINVAL
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The value specified by
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.Fa type
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is invalid.
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.El
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.\" .Pp
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.\" .Fn pthread_mutexattr_setprioceiling
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.\" may 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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.\" .Fn pthread_mutexattr_getprioceiling
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.\" may 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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.\" .Fn pthread_mutexattr_setprotocol
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.\" may 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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.\" .Fn pthread_mutexattr_getprotocol
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.\" may 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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.Pp
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.Fn pthread_mutexattr_destroy ,
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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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may 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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.Fn pthread_mutexattr_init ,
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.Fn pthread_mutexattr_destroy ,
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.Fn pthread_mutexattr_settype ,
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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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and
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.Fn pthread_mutexattr_gettype
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conform to
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.St -p1003.1-96 .
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