.\" $OpenBSD: pthread_rwlock_unlock.3,v 1.6 2003/06/02 11:19:48 jmc Exp $
.\" Copyright (c) 1998 Alex Nash
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.\" $FreeBSD: pthread_rwlock_unlock.3,v 1.2 1999/08/28 00:03:10 peter Exp $
.\"
.Dd August 4, 1998
.Dt PTHREAD_RWLOCK_UNLOCK 3
.Os
.Sh NAME
.Nm pthread_rwlock_unlock
.Nd release a read/write lock
.Sh SYNOPSIS
.Fd #include <pthread.h>
.Ft int
.Fn pthread_rwlock_unlock "pthread_rwlock_t *lock"
.Sh DESCRIPTION
The
.Fn pthread_rwlock_unlock
function is used to release the read/write lock previously obtained by
.Fn pthread_rwlock_rdlock ,
.Fn pthread_rwlock_wrlock ,
.Fn pthread_rwlock_tryrdlock ,
or
.Fn pthread_rwlock_trywrlock .
.Sh RETURN VALUES
If successful, the
.Fn pthread_rwlock_unlock
function will return zero.
Otherwise an error number will be returned to indicate the error.
.Pp
The results are undefined if
.Fa lock
is not held by the calling thread.
.Sh ERRORS
The
.Fn pthread_rwlock_unlock
function may fail if:
.Bl -tag -width Er
.It Bq Er EINVAL
The value specified by
.Fa lock
is invalid.
.It Bq Er EPERM
The current thread does not own the read/write lock.
.El
.Sh SEE ALSO
.Xr pthread_rwlock_rdlock 3 ,
.Xr pthread_rwlock_wrlock 3
.Sh STANDARDS
The
.Fn pthread_rwlock_unlock
function is expected to conform to
.St -susv2 .
.Sh HISTORY
The
.Fn pthread_rwlock_unlock
function first appeared in
.Fx 3.0
and
.Ox 2.5 .