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      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 (the "License").
      6  * You may not use this file except in compliance with the License.
      7  *
      8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
      9  * or http://www.opensolaris.org/os/licensing.
     10  * See the License for the specific language governing permissions
     11  * and limitations under the License.
     12  *
     13  * When distributing Covered Code, include this CDDL HEADER in each
     14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
     15  * If applicable, add the following below this CDDL HEADER, with the
     16  * fields enclosed by brackets "[]" replaced with your own identifying
     17  * information: Portions Copyright [yyyy] [name of copyright owner]
     18  *
     19  * CDDL HEADER END
     20  */
     21 
     22 /*
     23  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
     24  * Use is subject to license terms.
     25  */
     26 
     27 	.file	"_lwp_mutex_unlock.s"
     28 
     29 #include "SYS.h"
     30 #include <../assym.h>
     31 
     32 	ENTRY(_lwp_mutex_unlock)
     33 	membar	#LoadStore|#StoreStore
     34 	add	%o0, MUTEX_LOCK_WORD, %o1
     35 	ld	[%o1], %o2
     36 1:
     37 	clr	%o3				! clear lock/get waiter field
     38 	cas	[%o1], %o2, %o3			! atomically
     39 	cmp	%o2, %o3
     40 	bne,a,pn %icc, 1b
     41 	  mov	%o3, %o2
     42 	btst	WAITER_MASK, %o3		! check for waiters
     43 	beq,a,pt %icc,2f			! if no waiters
     44 	  clr 	%o0				! 	return 0
     45 						! else (note that %o0 is still
     46 						!	&mutex)
     47 	clr	%o1				! call kernel to wakeup waiter:
     48 	SYSTRAP_RVAL1(lwp_mutex_wakeup)		!    lwp_mutex_wakeup(mp, 0)
     49 	SYSLWPERR
     50 2: 	RET
     51 	SET_SIZE(_lwp_mutex_unlock)
     52