/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

	.file	"_lwp_mutex_unlock.s"

#include "SYS.h"
#include <../assym.h>

	ENTRY(_lwp_mutex_unlock)
	membar	#LoadStore|#StoreStore
	add	%o0, MUTEX_LOCK_WORD, %o1
	ld	[%o1], %o2
1:
	clr	%o3				! clear lock/get waiter field
	cas	[%o1], %o2, %o3			! atomically
	cmp	%o2, %o3
	bne,a,pn %icc, 1b
	  mov	%o3, %o2
	btst	WAITER_MASK, %o3		! check for waiters
	beq,a,pt %icc,2f			! if no waiters
	  clr 	%o0				! 	return 0
						! else (note that %o0 is still
						!	&mutex)
	clr	%o1				! call kernel to wakeup waiter:
	SYSTRAP_RVAL1(lwp_mutex_wakeup)		!    lwp_mutex_wakeup(mp, 0)
	SYSLWPERR
2: 	RET
	SET_SIZE(_lwp_mutex_unlock)