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Annotation of sys/arch/i386/include/lock.h, Revision 1.1.1.1

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_ */