1 /* libc-internal interface for mutex locks. Mach cthreads version.
2 Copyright (C) 1996-2023 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19 #ifndef _LIBC_LOCK_H
20 #define _LIBC_LOCK_H 1
21
22 #ifdef _LIBC
23
24 #include <tls.h>
25 #include <lowlevellock.h>
26
27 typedef unsigned int __libc_lock_t;
28 typedef struct
29 {
30 __libc_lock_t lock;
31 int cnt;
32 void *owner;
33 } __libc_lock_recursive_t;
34
35 typedef __libc_lock_recursive_t __rtld_lock_recursive_t;
36
37 #define __libc_lock_owner_self() \
38 (__LIBC_NO_TLS () ? (void *) 1 : THREAD_SELF)
39
40 #else
41 typedef struct __libc_lock_opaque__ __libc_lock_t;
42 typedef struct __libc_lock_recursive_opaque__ __libc_lock_recursive_t;
43 #endif
44
45 /* Define a lock variable NAME with storage class CLASS. The lock must be
46 initialized with __libc_lock_init before it can be used (or define it
47 with __libc_lock_define_initialized, below). Use `extern' for CLASS to
48 declare a lock defined in another module. In public structure
49 definitions you must use a pointer to the lock structure (i.e., NAME
50 begins with a `*'), because its storage size will not be known outside
51 of libc. */
52 #define __libc_lock_define(CLASS,NAME) \
53 CLASS __libc_lock_t NAME;
54
55 /* Define an initialized lock variable NAME with storage class CLASS. */
56 #define _LIBC_LOCK_INITIALIZER LLL_LOCK_INITIALIZER
57 #define __libc_lock_define_initialized(CLASS,NAME) \
58 CLASS __libc_lock_t NAME = LLL_LOCK_INITIALIZER;
59
60 /* Initialize the named lock variable, leaving it in a consistent, unlocked
61 state. */
62 #define __libc_lock_init(NAME) (NAME) = LLL_LOCK_INITIALIZER
63
64 /* Finalize the named lock variable, which must be locked. It cannot be
65 used again until __libc_lock_init is called again on it. This must be
66 called on a lock variable before the containing storage is reused. */
67 #define __libc_lock_fini __libc_lock_unlock
68 #define __libc_lock_fini_recursive __libc_lock_unlock_recursive
69 #define __rtld_lock_fini_recursive __rtld_lock_unlock_recursive
70
71 /* Lock the named lock variable. */
72 #define __libc_lock_lock(NAME) \
73 ({ lll_lock ((NAME), LLL_PRIVATE); 0; })
74
75 /* Lock the named lock variable. */
76 #define __libc_lock_trylock(NAME) lll_trylock (NAME)
77
78 /* Unlock the named lock variable. */
79 #define __libc_lock_unlock(NAME) \
80 ({ lll_unlock ((NAME), LLL_PRIVATE); 0; })
81
82 #define __libc_lock_define_recursive(CLASS,NAME) \
83 CLASS __libc_lock_recursive_t NAME;
84
85 #define _LIBC_LOCK_RECURSIVE_INITIALIZER { LLL_LOCK_INITIALIZER, 0, 0 }
86
87 #define __libc_lock_define_initialized_recursive(CLASS,NAME) \
88 CLASS __libc_lock_recursive_t NAME = _LIBC_LOCK_RECURSIVE_INITIALIZER;
89
90 #define __rtld_lock_define_recursive(CLASS,NAME) \
91 __libc_lock_define_recursive (CLASS, NAME)
92 #define _RTLD_LOCK_RECURSIVE_INITIALIZER \
93 _LIBC_LOCK_RECURSIVE_INITIALIZER
94 #define __rtld_lock_define_initialized_recursive(CLASS,NAME) \
95 __libc_lock_define_initialized_recursive (CLASS, NAME)
96
97 #define __libc_lock_init_recursive(NAME) \
98 ({ \
99 (NAME) = (__libc_lock_recursive_t)_LIBC_LOCK_RECURSIVE_INITIALIZER; \
100 0; \
101 })
102
103 #define __libc_lock_trylock_recursive(NAME) \
104 ({ \
105 __libc_lock_recursive_t *const __lock = &(NAME); \
106 void *__self = __libc_lock_owner_self (); \
107 int __r = 0; \
108 if (__self == __lock->owner) \
109 ++__lock->cnt; \
110 else if ((__r = lll_trylock (__lock->lock)) == 0) \
111 __lock->owner = __self, __lock->cnt = 1; \
112 __r; \
113 })
114
115 #define __libc_lock_lock_recursive(NAME) \
116 ({ \
117 __libc_lock_recursive_t *const __lock = &(NAME); \
118 void *__self = __libc_lock_owner_self (); \
119 if (__self != __lock->owner) \
120 { \
121 lll_lock (__lock->lock, 0); \
122 __lock->owner = __self; \
123 } \
124 ++__lock->cnt; \
125 (void)0; \
126 })
127
128 #define __libc_lock_unlock_recursive(NAME) \
129 ({ \
130 __libc_lock_recursive_t *const __lock = &(NAME); \
131 if (--__lock->cnt == 0) \
132 { \
133 __lock->owner = 0; \
134 lll_unlock (__lock->lock, 0); \
135 } \
136 })
137
138
139 #define __rtld_lock_initialize(NAME) \
140 (void) ((NAME) = (__rtld_lock_recursive_t) _RTLD_LOCK_RECURSIVE_INITIALIZER)
141 #define __rtld_lock_trylock_recursive(NAME) \
142 __libc_lock_trylock_recursive (NAME)
143 #define __rtld_lock_lock_recursive(NAME) \
144 __libc_lock_lock_recursive(NAME)
145 #define __rtld_lock_unlock_recursive(NAME) \
146 __libc_lock_unlock_recursive (NAME)
147
148 /* XXX for now */
149 #define __libc_rwlock_define __libc_lock_define
150 #define __libc_rwlock_define_initialized __libc_lock_define_initialized
151 #define __libc_rwlock_init __libc_lock_init
152 #define __libc_rwlock_fini __libc_lock_fini
153 #define __libc_rwlock_rdlock __libc_lock_lock
154 #define __libc_rwlock_wrlock __libc_lock_lock
155 #define __libc_rwlock_tryrdlock __libc_lock_trylock
156 #define __libc_rwlock_trywrlock __libc_lock_trylock
157 #define __libc_rwlock_unlock __libc_lock_unlock
158
159 struct __libc_cleanup_frame
160 {
161 void (*__fct) (void *);
162 void *__argp;
163 int __doit;
164 };
165
166 __extern_inline void
167 __libc_cleanup_fct (struct __libc_cleanup_frame *framep)
168 {
169 if (framep->__doit)
170 framep->__fct (framep->__argp);
171 }
172
173 /* Start a critical region with a cleanup function */
174 #define __libc_cleanup_region_start(DOIT, FCT, ARG) \
175 do \
176 { \
177 struct __libc_cleanup_frame __cleanup \
178 __attribute__ ((__cleanup__ (__libc_cleanup_fct))) = \
179 { .__fct = (FCT), .__argp = (ARG), .__doit = (DOIT) };
180
181 /* This one closes the brace above. */
182 #define __libc_cleanup_region_end(DOIT) \
183 __cleanup.__doit = (DOIT); \
184 } \
185 while (0)
186
187 #define __libc_cleanup_end(DOIT) __cleanup.__doit = (DOIT);
188
189 #define __libc_cleanup_push(fct, arg) __libc_cleanup_region_start (1, fct, arg)
190 #define __libc_cleanup_pop(execute) __libc_cleanup_region_end (execute)
191
192 /* Use mutexes as once control variables. */
193
194 struct __libc_once
195 {
196 __libc_lock_t lock;
197 int done;
198 };
199
200 #define __libc_once_define(CLASS,NAME) \
201 CLASS struct __libc_once NAME = { _LIBC_LOCK_INITIALIZER, 0 }
202
203 /* Call handler iff the first call. */
204 #define __libc_once(ONCE_CONTROL, INIT_FUNCTION) \
205 do { \
206 __libc_lock_lock (ONCE_CONTROL.lock); \
207 if (!ONCE_CONTROL.done) \
208 (INIT_FUNCTION) (); \
209 ONCE_CONTROL.done = 1; \
210 __libc_lock_unlock (ONCE_CONTROL.lock); \
211 } while (0)
212
213 /* Get once control variable. */
214 #define __libc_once_get(ONCE_CONTROL) ((ONCE_CONTROL).done != 0)
215
216 #ifdef _LIBC
217 /* We need portable names for some functions. E.g., when they are
218 used as argument to __libc_cleanup_region_start. */
219 #define __libc_mutex_unlock __libc_lock_unlock
220
221 /* Hide the definitions which are only supposed to be used inside libc in
222 a separate file. This file is not present in the installation! */
223 # include <libc-lockP.h>
224 #endif
225
226 #endif /* libc-lock.h */