| 1 | /* |
| 2 | * Copyright (c) 1991 Regents of the University of California. |
| 3 | * All rights reserved. |
| 4 | * |
| 5 | * This code is derived from software contributed to Berkeley by |
| 6 | * The Mach Operating System project at Carnegie-Mellon University. |
| 7 | * |
| 8 | * Redistribution and use in source and binary forms, with or without |
| 9 | * modification, are permitted provided that the following conditions |
| 10 | * are met: |
| 11 | * 1. Redistributions of source code must retain the above copyright |
| 12 | * notice, this list of conditions and the following disclaimer. |
| 13 | * 2. Redistributions in binary form must reproduce the above copyright |
| 14 | * notice, this list of conditions and the following disclaimer in the |
| 15 | * documentation and/or other materials provided with the distribution. |
| 16 | * 3. All advertising materials mentioning features or use of this software |
| 17 | * must display the following acknowledgement: |
| 18 | * This product includes software developed by the University of |
| 19 | * California, Berkeley and its contributors. |
| 20 | * 4. Neither the name of the University nor the names of its contributors |
| 21 | * may be used to endorse or promote products derived from this software |
| 22 | * without specific prior written permission. |
| 23 | * |
| 24 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
| 25 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| 26 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| 27 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
| 28 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| 29 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
| 30 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| 31 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| 32 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| 33 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| 34 | * SUCH DAMAGE. |
| 35 | * |
| 36 | * @(#)lock.h 7.3 (Berkeley) 4/21/91 |
| 37 | * |
| 38 | * |
| 39 | * Copyright (c) 1987, 1990 Carnegie-Mellon University. |
| 40 | * All rights reserved. |
| 41 | * |
| 42 | * Authors: Avadis Tevanian, Jr., Michael Wayne Young |
| 43 | * |
| 44 | * Permission to use, copy, modify and distribute this software and |
| 45 | * its documentation is hereby granted, provided that both the copyright |
| 46 | * notice and this permission notice appear in all copies of the |
| 47 | * software, derivative works or modified versions, and any portions |
| 48 | * thereof, and that both notices appear in supporting documentation. |
| 49 | * |
| 50 | * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" |
| 51 | * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND |
| 52 | * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. |
| 53 | * |
| 54 | * Carnegie Mellon requests users of this software to return to |
| 55 | * |
| 56 | * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU |
| 57 | * School of Computer Science |
| 58 | * Carnegie Mellon University |
| 59 | * Pittsburgh PA 15213-3890 |
| 60 | * |
| 61 | * any improvements or extensions that they make and grant Carnegie the |
| 62 | * rights to redistribute these changes. |
| 63 | */ |
| 64 | |
| 65 | /* |
| 66 | * Locking primitives definitions |
| 67 | */ |
| 68 | |
| 69 | #ifndef _LOCK_H_ |
| 70 | #define _LOCK_H_ |
| 71 | |
| 72 | #define NCPUS 1 /* XXX */ |
| 73 | |
| 74 | /* |
| 75 | * A simple spin lock. |
| 76 | */ |
| 77 | |
| 78 | struct slock { |
| 79 | int lock_data; /* in general 1 bit is sufficient */ |
| 80 | }; |
| 81 | |
| 82 | typedef struct slock simple_lock_data_t; |
| 83 | typedef struct slock *simple_lock_t; |
| 84 | |
| 85 | /* |
| 86 | * The general lock structure. Provides for multiple readers, |
| 87 | * upgrading from read to write, and sleeping until the lock |
| 88 | * can be gained. |
| 89 | */ |
| 90 | |
| 91 | struct lock { |
| 92 | #ifdef vax |
| 93 | /* |
| 94 | * Efficient VAX implementation -- see field description below. |
| 95 | */ |
| 96 | unsigned int read_count:16, |
| 97 | want_upgrade:1, |
| 98 | want_write:1, |
| 99 | waiting:1, |
| 100 | can_sleep:1, |
| 101 | :0; |
| 102 | |
| 103 | simple_lock_data_t interlock; |
| 104 | #else vax |
| 105 | #ifdef ns32000 |
| 106 | /* |
| 107 | * Efficient ns32000 implementation -- |
| 108 | * see field description below. |
| 109 | */ |
| 110 | simple_lock_data_t interlock; |
| 111 | unsigned int read_count:16, |
| 112 | want_upgrade:1, |
| 113 | want_write:1, |
| 114 | waiting:1, |
| 115 | can_sleep:1, |
| 116 | :0; |
| 117 | |
| 118 | #else ns32000 |
| 119 | /* Only the "interlock" field is used for hardware exclusion; |
| 120 | * other fields are modified with normal instructions after |
| 121 | * acquiring the interlock bit. |
| 122 | */ |
| 123 | simple_lock_data_t |
| 124 | interlock; /* Interlock for remaining fields */ |
| 125 | boolean_t want_write; /* Writer is waiting, or locked for write */ |
| 126 | boolean_t want_upgrade; /* Read-to-write upgrade waiting */ |
| 127 | boolean_t waiting; /* Someone is sleeping on lock */ |
| 128 | boolean_t can_sleep; /* Can attempts to lock go to sleep */ |
| 129 | int read_count; /* Number of accepted readers */ |
| 130 | #endif /* ns32000 */ |
| 131 | #endif /* vax */ |
| 132 | char *thread; /* Thread that has lock, if recursive locking allowed */ |
| 133 | /* (should be thread_t, but but we then have mutually |
| 134 | recursive definitions) */ |
| 135 | int recursion_depth;/* Depth of recursion */ |
| 136 | }; |
| 137 | |
| 138 | typedef struct lock lock_data_t; |
| 139 | typedef struct lock *lock_t; |
| 140 | |
| 141 | #if NCPUS > 1 |
| 142 | void simple_lock_init(); |
| 143 | void simple_lock(); |
| 144 | void simple_unlock(); |
| 145 | boolean_t simple_lock_try(); |
| 146 | #else NCPUS > 1 |
| 147 | /* |
| 148 | * No multiprocessor locking is necessary. |
| 149 | */ |
| 150 | #define simple_lock_init(l) |
| 151 | #define simple_lock(l) |
| 152 | #define simple_unlock(l) |
| 153 | #define simple_lock_try(l) (1) /* always succeeds */ |
| 154 | #endif /* NCPUS > 1 */ |
| 155 | |
| 156 | /* Sleep locks must work even if no multiprocessing */ |
| 157 | |
| 158 | void lock_init(); |
| 159 | void lock_sleepable(); |
| 160 | void lock_write(); |
| 161 | void lock_read(); |
| 162 | void lock_done(); |
| 163 | boolean_t lock_read_to_write(); |
| 164 | void lock_write_to_read(); |
| 165 | boolean_t lock_try_write(); |
| 166 | boolean_t lock_try_read(); |
| 167 | boolean_t lock_try_read_to_write(); |
| 168 | |
| 169 | #define lock_read_done(l) lock_done(l) |
| 170 | #define lock_write_done(l) lock_done(l) |
| 171 | |
| 172 | void lock_set_recursive(); |
| 173 | void lock_clear_recursive(); |
| 174 | |
| 175 | #endif /* !_LOCK_H_ */ |