1/*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License, Version 1.0 only
6 * (the "License").  You may not use this file except in compliance
7 * with the License.
8 *
9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10 * or http://www.opensolaris.org/os/licensing.
11 * See the License for the specific language governing permissions
12 * and limitations under the License.
13 *
14 * When distributing Covered Code, include this CDDL HEADER in each
15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16 * If applicable, add the following below this CDDL HEADER, with the
17 * fields enclosed by brackets "[]" replaced with your own identifying
18 * information: Portions Copyright [yyyy] [name of copyright owner]
19 *
20 * CDDL HEADER END
21 */
22/*
23 * Copyright 1996-2002 Sun Microsystems, Inc.  All rights reserved.
24 * Use is subject to license terms.
25 */
26
27/*	Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T	*/
28/*	  All Rights Reserved	*/
29
30
31#pragma ident	"%Z%%M%	%I%	%E% SMI"
32
33#include <sys/param.h>
34#include <sys/types.h>
35#include <sys/sysmacros.h>
36#include <sys/systm.h>
37#include <sys/errno.h>
38#include <sys/thread.h>
39#include <sys/disp.h>
40#include <sys/debug.h>
41#include <sys/cpuvar.h>
42
43
44/*
45 * The calling LWP is preempted in favor of some other LWP.
46 */
47int
48yield()
49{
50	kthread_t *t = curthread;
51	klwp_t *lwp = ttolwp(t);
52
53	thread_lock(t);
54	lwp->lwp_ru.nvcsw++;
55	THREAD_TRANSITION(t);
56	CL_YIELD(t);		/* does setbackdq */
57	thread_unlock_nopreempt(t);
58	swtch();		/* clears cpu_runrun and cpu_kprunrun */
59
60	return (0);
61}
62