1.\" $NetBSD: sem_post.3,v 1.3 2012/03/08 22:13:05 wiz Exp $ 2.\" 3.\" Copyright (C) 2000 Jason Evans <jasone@FreeBSD.org>. 4.\" All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice(s), this list of conditions and the following disclaimer as 11.\" the first lines of this file unmodified other than the possible 12.\" addition of one or more copyright notices. 13.\" 2. Redistributions in binary form must reproduce the above copyright 14.\" notice(s), this list of conditions and the following disclaimer in 15.\" the documentation and/or other materials provided with the 16.\" distribution. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY 19.\" EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 21.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE 22.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 23.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 24.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR 25.\" BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 26.\" WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE 27.\" OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, 28.\" EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 29.\" 30.Dd February 29, 2012 31.Dt SEM_POST 3 32.Os 33.Sh NAME 34.Nm sem_post 35.Nd increment (unlock) a semaphore 36.Sh LIBRARY 37.Lb librt 38.Sh SYNOPSIS 39.In semaphore.h 40.Ft int 41.Fn sem_post "sem_t *sem" 42.Sh DESCRIPTION 43The 44.Fn sem_post 45function increments (unlocks) the semaphore pointed to by 46.Fa sem . 47If there are threads blocked on the semaphore when 48.Fn sem_post 49is called, then the highest priority thread that has been blocked the longest on 50the semaphore will be allowed to return from 51.Fn sem_wait 52or 53.Fn sem_timedwait . 54.Pp 55.Fn sem_post 56is signal-reentrant and may be called within signal handlers. 57.Sh RETURN VALUES 58.Rv -std sem_post 59.Sh ERRORS 60.Fn sem_post 61will fail if: 62.Bl -tag -width Er 63.It Bq Er EINVAL 64.Fa sem 65points to an invalid semaphore. 66.El 67.Sh SEE ALSO 68.Xr sem_timedwait 3 , 69.Xr sem_trywait 3 , 70.Xr sem_wait 3 71.Sh STANDARDS 72.Fn sem_post 73conforms to 74.St -p1003.1-96 . 75