/*
 * 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)