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Annotation of sys/arch/i386/include/lock.h, Revision 1.1

1.1     ! nbrk        1: /*     $OpenBSD: lock.h,v 1.5 2007/05/29 18:18:20 tom Exp $    */
        !             2: /*     $NetBSD: lock.h,v 1.1.2.2 2000/05/03 14:40:55 sommerfeld Exp $  */
        !             3:
        !             4: /*-
        !             5:  * Copyright (c) 2000 The NetBSD Foundation, Inc.
        !             6:  * All rights reserved.
        !             7:  *
        !             8:  * This code is derived from software contributed to The NetBSD Foundation
        !             9:  * by Jason R. Thorpe.
        !            10:  *
        !            11:  * Redistribution and use in source and binary forms, with or without
        !            12:  * modification, are permitted provided that the following conditions
        !            13:  * are met:
        !            14:  * 1. Redistributions of source code must retain the above copyright
        !            15:  *    notice, this list of conditions and the following disclaimer.
        !            16:  * 2. Redistributions in binary form must reproduce the above copyright
        !            17:  *    notice, this list of conditions and the following disclaimer in the
        !            18:  *    documentation and/or other materials provided with the distribution.
        !            19:  * 3. All advertising materials mentioning features or use of this software
        !            20:  *    must display the following acknowledgement:
        !            21:  *     This product includes software developed by the NetBSD
        !            22:  *     Foundation, Inc. and its contributors.
        !            23:  * 4. Neither the name of The NetBSD Foundation nor the names of its
        !            24:  *    contributors may be used to endorse or promote products derived
        !            25:  *    from this software without specific prior written permission.
        !            26:  *
        !            27:  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
        !            28:  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
        !            29:  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
        !            30:  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
        !            31:  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
        !            32:  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
        !            33:  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
        !            34:  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
        !            35:  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
        !            36:  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
        !            37:  * POSSIBILITY OF SUCH DAMAGE.
        !            38:  */
        !            39:
        !            40: /*
        !            41:  * Machine-dependent spin lock operations.
        !            42:  */
        !            43:
        !            44: #ifndef _I386_LOCK_H_
        !            45: #define        _I386_LOCK_H_
        !            46:
        !            47: typedef        __volatile int          __cpu_simple_lock_t;
        !            48:
        !            49: #define        __SIMPLELOCK_LOCKED     1
        !            50: #define        __SIMPLELOCK_UNLOCKED   0
        !            51:
        !            52: /*
        !            53:  * compiler barrier: prevent reordering of instructions.
        !            54:  * XXX something similar will move to <sys/cdefs.h>
        !            55:  * or thereabouts.
        !            56:  * This prevents the compiler from reordering code around
        !            57:  * this "instruction", acting as a sequence point for code generation.
        !            58:  */
        !            59:
        !            60: #define __lockbarrier() __asm __volatile("": : :"memory")
        !            61:
        !            62: #define SPINLOCK_SPIN_HOOK     __asm __volatile("pause": : :"memory")
        !            63:
        !            64: #ifdef LOCKDEBUG
        !            65:
        !            66: extern void __cpu_simple_lock_init(__cpu_simple_lock_t *);
        !            67: extern void __cpu_simple_lock(__cpu_simple_lock_t *);
        !            68: extern int __cpu_simple_lock_try(__cpu_simple_lock_t *);
        !            69: extern void __cpu_simple_unlock(__cpu_simple_lock_t *);
        !            70:
        !            71: #else
        !            72:
        !            73: #include <machine/atomic.h>
        !            74:
        !            75: static __inline void __cpu_simple_lock_init(__cpu_simple_lock_t *)
        !            76:        __attribute__((__unused__));
        !            77: static __inline void __cpu_simple_lock(__cpu_simple_lock_t *)
        !            78:        __attribute__((__unused__));
        !            79: static __inline int __cpu_simple_lock_try(__cpu_simple_lock_t *)
        !            80:        __attribute__((__unused__));
        !            81: static __inline void __cpu_simple_unlock(__cpu_simple_lock_t *)
        !            82:        __attribute__((__unused__));
        !            83:
        !            84: static __inline void
        !            85: __cpu_simple_lock_init(__cpu_simple_lock_t *lockp)
        !            86: {
        !            87:        *lockp = __SIMPLELOCK_UNLOCKED;
        !            88:        __lockbarrier();
        !            89: }
        !            90:
        !            91: static __inline void
        !            92: __cpu_simple_lock(__cpu_simple_lock_t *lockp)
        !            93: {
        !            94:        while (i386_atomic_testset_i(lockp, __SIMPLELOCK_LOCKED)
        !            95:            == __SIMPLELOCK_LOCKED)
        !            96:                SPINLOCK_SPIN_HOOK;
        !            97:        __lockbarrier();
        !            98: }
        !            99:
        !           100: static __inline int
        !           101: __cpu_simple_lock_try(__cpu_simple_lock_t *lockp)
        !           102: {
        !           103:        int r = (i386_atomic_testset_i(lockp, __SIMPLELOCK_LOCKED)
        !           104:            == __SIMPLELOCK_UNLOCKED);
        !           105:
        !           106:        __lockbarrier();
        !           107:
        !           108:        return (r);
        !           109: }
        !           110:
        !           111: static __inline void
        !           112: __cpu_simple_unlock(__cpu_simple_lock_t *lockp)
        !           113: {
        !           114:        __lockbarrier();
        !           115:        *lockp = __SIMPLELOCK_UNLOCKED;
        !           116: }
        !           117:
        !           118: #endif /* !LOCKDEBUG */
        !           119:
        !           120: #ifdef _KERNEL
        !           121: extern int rw_cas_486(volatile unsigned long *, unsigned long, unsigned long);
        !           122: #define rw_cas rw_cas_486
        !           123: #endif
        !           124:
        !           125: #endif /* _I386_LOCK_H_ */