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
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
|
/*
* Mach Operating System
* Copyright (c) 1993-1987 Carnegie Mellon University
* All Rights Reserved.
*
* 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 Mellon
* the rights to redistribute these changes.
*/
/*
* File: kern/lock.h
* Author: Avadis Tevanian, Jr., Michael Wayne Young
* Date: 1985
*
* Locking primitives definitions
*/
#ifndef _KERN_LOCK_H_
#define _KERN_LOCK_H_
#include <mach/boolean.h>
#include <mach/machine/vm_types.h>
#if NCPUS > 1
#include <machine/lock.h>/*XXX*/
#endif
#define MACH_SLOCKS ((NCPUS > 1) || MACH_LDEBUG)
/*
* A simple spin lock.
*/
struct slock {
volatile natural_t lock_data; /* in general 1 bit is sufficient */
struct {} is_a_simple_lock;
};
/*
* Used by macros to assert that the given argument is a simple
* lock.
*/
#define simple_lock_assert(l) (void) &(l)->is_a_simple_lock
typedef struct slock simple_lock_data_t;
typedef struct slock *simple_lock_t;
#if MACH_SLOCKS
/*
* Use the locks.
*/
#define decl_simple_lock_data(class,name) \
class simple_lock_data_t name;
#define simple_lock_addr(lock) (simple_lock_assert(&(lock)), \
&(lock))
#if (NCPUS > 1)
/*
* The single-CPU debugging routines are not valid
* on a multiprocessor.
*/
#define simple_lock_taken(lock) (simple_lock_assert(lock), \
1) /* always succeeds */
#define check_simple_locks()
#define check_simple_locks_enable()
#define check_simple_locks_disable()
#else /* NCPUS > 1 */
/*
* Use our single-CPU locking test routines.
*/
extern void simple_lock_init(simple_lock_t);
extern void _simple_lock(simple_lock_t,
const char *, const char *);
extern void simple_unlock(simple_lock_t);
extern boolean_t _simple_lock_try(simple_lock_t,
const char *, const char *);
/* We provide simple_lock and simple_lock_try so that we can save the
location. */
#define XSTR(x) #x
#define STR(x) XSTR(x)
#define LOCATION __FILE__ ":" STR(__LINE__)
#define simple_lock(lock) _simple_lock((lock), #lock, LOCATION)
#define simple_lock_try(lock) _simple_lock_try((lock), #lock, LOCATION)
#define simple_lock_pause()
#define simple_lock_taken(lock) (simple_lock_assert(lock), \
(lock)->lock_data)
extern void check_simple_locks(void);
extern void check_simple_locks_enable(void);
extern void check_simple_locks_disable(void);
#endif /* NCPUS > 1 */
#else /* MACH_SLOCKS */
/*
* Do not allocate storage for locks if not needed.
*/
struct simple_lock_data_empty { struct {} is_a_simple_lock; };
#define decl_simple_lock_data(class,name) \
class struct simple_lock_data_empty name;
#define simple_lock_addr(lock) (simple_lock_assert(&(lock)), \
(simple_lock_t)0)
/*
* No multiprocessor locking is necessary.
*/
#define simple_lock_init(l) simple_lock_assert(l)
#define simple_lock(l) simple_lock_assert(l)
#define simple_unlock(l) simple_lock_assert(l)
#define simple_lock_try(l) (simple_lock_assert(l), \
TRUE) /* always succeeds */
#define simple_lock_taken(l) (simple_lock_assert(l), \
1) /* always succeeds */
#define check_simple_locks()
#define check_simple_locks_enable()
#define check_simple_locks_disable()
#define simple_lock_pause()
#endif /* MACH_SLOCKS */
#define decl_mutex_data(class,name) decl_simple_lock_data(class,name)
#define mutex_try(l) simple_lock_try(l)
#define mutex_lock(l) simple_lock(l)
#define mutex_unlock(l) simple_unlock(l)
#define mutex_init(l) simple_lock_init(l)
/*
* The general lock structure. Provides for multiple readers,
* upgrading from read to write, and sleeping until the lock
* can be gained.
*
* On some architectures, assembly language code in the 'inline'
* program fiddles the lock structures. It must be changed in
* concert with the structure layout.
*
* Only the "interlock" field is used for hardware exclusion;
* other fields are modified with normal instructions after
* acquiring the interlock bit.
*/
struct lock {
struct thread *thread; /* Thread that has lock, if
recursive locking allowed */
unsigned int read_count:16, /* Number of accepted readers */
/* boolean_t */ want_upgrade:1, /* Read-to-write upgrade waiting */
/* boolean_t */ want_write:1, /* Writer is waiting, or
locked for write */
/* boolean_t */ waiting:1, /* Someone is sleeping on lock */
/* boolean_t */ can_sleep:1, /* Can attempts to lock go to sleep? */
recursion_depth:12, /* Depth of recursion */
:0;
#if MACH_LDEBUG
struct thread *writer;
#endif /* MACH_LDEBUG */
decl_simple_lock_data(,interlock)
/* Hardware interlock field.
Last in the structure so that
field offsets are the same whether
or not it is present. */
};
typedef struct lock lock_data_t;
typedef struct lock *lock_t;
/* Sleep locks must work even if no multiprocessing */
extern void lock_init(lock_t, boolean_t);
extern void lock_sleepable(lock_t, boolean_t);
extern void lock_write(lock_t);
extern void lock_read(lock_t);
extern void lock_done(lock_t);
extern boolean_t lock_read_to_write(lock_t);
extern void lock_write_to_read(lock_t);
extern boolean_t lock_try_write(lock_t);
extern boolean_t lock_try_read(lock_t);
extern boolean_t lock_try_read_to_write(lock_t);
#define lock_read_done(l) lock_done(l)
#define lock_write_done(l) lock_done(l)
#define lock_taken(l) ((l)->want_write || (l)->read_count)
extern void lock_set_recursive(lock_t);
extern void lock_clear_recursive(lock_t);
/* Lock debugging support. */
#if ! MACH_LDEBUG
#define have_read_lock(l) 1
#define have_write_lock(l) 1
#else /* MACH_LDEBUG */
/* XXX: We don't keep track of readers, so this is an approximation. */
#define have_read_lock(l) ((l)->read_count > 0)
#define have_write_lock(l) ((l)->writer == current_thread())
#endif /* MACH_LDEBUG */
#define have_lock(l) (have_read_lock(l) || have_write_lock(l))
void db_show_all_slocks(void);
#endif /* _KERN_LOCK_H_ */
|
