/*

 * 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.

 */

#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)