usr/src/lib/libc/sparc/sys/_lwp_mutex_unlock.s

   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)