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.\" Copyright (c) 2004 Michael Telahun Makonnen
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\" $FreeBSD$
.\"
.Dd January 22, 2004
.Dt PTHREAD_SPIN_INIT 3
.Os
.Sh NAME
.Nm pthread_spin_init , pthread_spin_destroy
.Nd "initialize or destroy a spin lock"
.Sh LIBRARY
.Lb libpthread
.Sh SYNOPSIS
.In pthread.h
.Ft int
.Fn pthread_spin_init "pthread_spinlock_t *lock" "int pshared"
.Ft int
.Fn pthread_spin_destroy "pthread_spinlock_t *lock"
.Sh DESCRIPTION
The
.Fn pthread_spin_init
function will initialize
.Fa lock
to an unlocked state and
allocate any resources necessary to begin using it.
If
.Fa pshared
is set to
.Dv PTHREAD_PROCESS_SHARED ,
any thread,
whether belonging to the process in which the spinlock was created or not,
that has access to the memory area where
.Fa lock
resides, can use
.Fa lock .
If it is set to
.Dv PTHREAD_PROCESS_PRIVATE ,
it can only be used by threads within the same process.
.Pp
The
.Fn pthread_spin_destroy
function will destroy
.Fa lock
and release any resources that may have been allocated on its behalf.
.Sh RETURN VALUES
If successful,
both
.Fn pthread_spin_init
and
.Fn pthread_spin_destroy
will return zero.
Otherwise, an error number will be returned to indicate the error.
.Pp
Neither of these functions will return
.Er EINTR .
.Sh ERRORS
The
.Fn pthread_spin_init
and
.Fn pthread_spin_destroy
functions will fail if:
.Bl -tag -width Er
.It Bq Er EBUSY
An attempt to initialize or destroy
.Fa lock
while it is in use.
.It Bq Er EINVAL
The value specified by
.Fa lock
is invalid.
.El
.Pp
The
.Fn pthread_spin_init
function will fail if:
.Bl -tag -width Er
.It Bq Er EAGAIN
Insufficient resources,
other than memory,
to initialize
.Fa lock .
.It Bq Er ENOMEM
Insufficient memory to initialize
.Fa lock .
.El
.Sh SEE ALSO
.Xr pthread_spin_lock 3 ,
.Xr pthread_spin_unlock 3
.Sh HISTORY
The
.Fn pthread_spin_init
and
.Fn pthread_spin_destroy
functions first appeared in
.Lb libkse
in
.Fx 5.2 ,
and in
.Lb libthr
in
.Fx 5.3 .
.Sh BUGS
The implementation of
.Fn pthread_spin_init
does not fully conform to
.St -p1003.2
because the
.Fa pshared
argument is ignored in
.Lb libthr ,
and in
.Lb libkse
if any value other than
.Dv PTHREAD_PROCESSES_PRIVATE
is specified, it returns
.Er EINVAL .
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