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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_LOCK 3
.Os
.Sh NAME
.Nm pthread_spin_lock , pthread_spin_trylock , pthread_spin_unlock
.Nd "lock or unlock a spin lock"
.Sh LIBRARY
.Lb libpthread
.Lb libthr
.Sh SYNOPSIS
.In pthread.h
.Ft int
.Fn pthread_spin_lock "pthread_spinlock_t *lock"
.Ft int
.Fn pthread_spin_trylock "pthread_spinlock_t *lock"
.Ft int
.Fn pthread_spin_unlock "pthread_spinlock_t *lock"
.Sh DESCRIPTION
The
.Fn pthread_spin_lock
function will acquire
.Fa lock
if it is not currently owned by another thread.
If the lock cannot be acquired immediately, it will
spin attempting to acquire the lock (it will not sleep) until
it becomes available.
.Pp
The
.Fn pthread_spin_trylock
function is the same as
.Fn pthread_spin_lock
except that if it cannot acquire
.Fa lock
immediately it will return with an error.
.Pp
The
.Fn pthread_spin_unlock
function will release
.Fa lock ,
which must have been previously locked by a call to
.Fn pthread_spin_lock
or
.Fn pthread_spin_trylock .
.Sh RETURN VALUES
If successful, all these functions will return zero.
Otherwise, an error number will be returned to indicate the error.
.Pp
None of these functions will return
.Er EINTR .
.Sh ERRORS
The
.Fn pthread_spin_lock ,
.Fn pthread_spin_trylock
and
.Fn pthread_spin_unlock
functions will fail if:
.Bl -tag -width Er
.It Bq Er EINVAL
The value specified by
.Fa lock
is invalid or is not initialized.
.El
.Pp
The
.Fn pthread_spin_lock
function may fail if:
.Bl -tag -width Er
.It Bq Er EDEADLK
The calling thread already owns the lock.
.El
.Pp
The
.Fn pthread_spin_trylock
function will fail if:
.Bl -tag -width Er
.It Bq Er EBUSY
Another thread currently holds
.Fa lock .
.El
.Pp
The
.Fn pthread_spin_unlock
function may fail if:
.Bl -tag -width Er
.It Bq Er EPERM
The calling thread does not own
.Fa lock .
.El
.Sh SEE ALSO
.Xr pthread_spin_destroy 3 ,
.Xr pthread_spin_init 3
.Sh HISTORY
The
.Fn pthread_spin_lock ,
.Fn pthread_spin_trylock
and
.Fn pthread_spin_unlock
functions first appeared in
.Lb libpthread
in
.Fx 5.2 ,
and in
.Lb libthr
in
.Fx 5.3 .
.Sh BUGS
The implementation of
.Fn pthread_spin_lock ,
.Fn pthread_spin_trylock
and
.Fn pthread_spin_unlock
is expected to conform to
.St -p1003.2 .
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