1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
|
/* $NetBSD: lock.h,v 1.8 1994/10/30 19:11:11 cgd Exp $ */
/*
* Copyright (c) 1991, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* The Mach Operating System project at Carnegie-Mellon University.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)lock.h 8.1 (Berkeley) 6/11/93
*
*
* Copyright (c) 1987, 1990 Carnegie-Mellon University.
* All rights reserved.
*
* Authors: Avadis Tevanian, Jr., Michael Wayne Young
*
* Permission to use, copy, modify and distribute this software and
* its documentation is hereby granted, provided that both the copyright
* notice and this permission notice appear in all copies of the
* software, derivative works or modified versions, and any portions
* thereof, and that both notices appear in supporting documentation.
*
* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
* FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
*
* Carnegie Mellon requests users of this software to return to
*
* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
* School of Computer Science
* Carnegie Mellon University
* Pittsburgh PA 15213-3890
*
* any improvements or extensions that they make and grant Carnegie the
* rights to redistribute these changes.
*/
/*
* Locking primitives definitions
*/
#ifndef _LOCK_H_
#define _LOCK_H_
#define NCPUS 1 /* XXX */
/*
* A simple spin lock.
*/
struct slock {
int lock_data; /* in general 1 bit is sufficient */
};
typedef struct slock simple_lock_data_t;
typedef struct slock *simple_lock_t;
/*
* The general lock structure. Provides for multiple readers,
* upgrading from read to write, and sleeping until the lock
* can be gained.
*/
struct lock {
#ifdef vax
/*
* Efficient VAX implementation -- see field description below.
*/
unsigned int read_count:16,
want_upgrade:1,
want_write:1,
waiting:1,
can_sleep:1,
:0;
simple_lock_data_t interlock;
#else /* vax */
#ifdef ns32000
/*
* Efficient ns32000 implementation --
* see field description below.
*/
simple_lock_data_t interlock;
unsigned int read_count:16,
want_upgrade:1,
want_write:1,
waiting:1,
can_sleep:1,
:0;
#else /* ns32000 */
/* Only the "interlock" field is used for hardware exclusion;
* other fields are modified with normal instructions after
* acquiring the interlock bit.
*/
simple_lock_data_t
interlock; /* Interlock for remaining fields */
boolean_t want_write; /* Writer is waiting, or locked for write */
boolean_t want_upgrade; /* Read-to-write upgrade waiting */
boolean_t waiting; /* Someone is sleeping on lock */
boolean_t can_sleep; /* Can attempts to lock go to sleep */
int read_count; /* Number of accepted readers */
#endif /* ns32000 */
#endif /* vax */
void *thread; /* Thread that has lock, if recursive locking allowed */
/* (should be thread_t, but but we then have mutually
recursive definitions) */
int recursion_depth;/* Depth of recursion */
};
typedef struct lock lock_data_t;
typedef struct lock *lock_t;
#if NCPUS > 1
__BEGIN_DECLS
void simple_lock __P((simple_lock_t));
void simple_lock_init __P((simple_lock_t));
boolean_t simple_lock_try __P((simple_lock_t));
void simple_unlock __P((simple_lock_t));
__END_DECLS
#else /* No multiprocessor locking is necessary. */
#define simple_lock(l)
#define simple_lock_init(l)
#define simple_lock_try(l) (1) /* Always succeeds. */
#define simple_unlock(l)
#endif
/* Sleep locks must work even if no multiprocessing. */
#define lock_read_done(l) lock_done(l)
#define lock_write_done(l) lock_done(l)
void lock_clear_recursive __P((lock_t));
void lock_done __P((lock_t));
void lock_init __P((lock_t, boolean_t));
void lock_read __P((lock_t));
boolean_t lock_read_to_write __P((lock_t));
void lock_set_recursive __P((lock_t));
void lock_sleepable __P((lock_t, boolean_t));
boolean_t lock_try_read __P((lock_t));
boolean_t lock_try_read_to_write __P((lock_t));
boolean_t lock_try_write __P((lock_t));
void lock_write __P((lock_t));
void lock_write_to_read __P((lock_t));
#endif /* !_LOCK_H_ */
|
