.\" Copyright (c) 2004 Michael Telahun Makonnen
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.\" $FreeBSD: head/share/man/man3/pthread_spin_init.3 301077 2016-05-31 21:16:34Z jilles $
.\"
.Dd May 31, 2016
.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 .
Support for process-shared spinlocks appeared in
.Fx 11.0 .