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4d0d66bb MD |
1 | #ifndef _URCU_TLS_COMPAT_H |
2 | #define _URCU_TLS_COMPAT_H | |
3 | ||
4 | /* | |
5 | * urcu/tls-compat.h | |
6 | * | |
7 | * Userspace RCU library - Thread-Local Storage Compatibility Header | |
8 | * | |
9 | * Copyright 2012 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
10 | * | |
11 | * This library is free software; you can redistribute it and/or | |
12 | * modify it under the terms of the GNU Lesser General Public | |
13 | * License as published by the Free Software Foundation; either | |
14 | * version 2.1 of the License, or (at your option) any later version. | |
15 | * | |
16 | * This library is distributed in the hope that it will be useful, | |
17 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
18 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
19 | * Lesser General Public License for more details. | |
20 | * | |
21 | * You should have received a copy of the GNU Lesser General Public | |
22 | * License along with this library; if not, write to the Free Software | |
23 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | |
24 | */ | |
25 | ||
26 | #include <stdlib.h> | |
27 | #include <urcu/config.h> | |
28 | #include <urcu/compiler.h> | |
29 | #include <urcu/arch.h> | |
30 | ||
31 | #ifdef __cplusplus | |
32 | extern "C" { | |
33 | #endif | |
34 | ||
35 | #ifdef CONFIG_RCU_TLS /* Based on ax_tls.m4 */ | |
36 | ||
c85e62f3 LJ |
37 | /* |
38 | * Hint: How to define/declare TLS variables of compound types | |
39 | * such as array or function pointers? | |
40 | * | |
41 | * Answer: Use typedef to assign a type_name to the compound type. | |
42 | * Example: Define a TLS variable which is an int array with len=4: | |
43 | * | |
44 | * typedef int my_int_array_type[4]; | |
45 | * DEFINE_URCU_TLS(my_int_array_type, var_name); | |
46 | * | |
47 | * Another exmaple: | |
48 | * typedef void (*call_rcu_flavor)(struct rcu_head *, XXXX); | |
49 | * DECLARE_URCU_TLS(call_rcu_flavor, p_call_rcu); | |
fa320ad0 LJ |
50 | * |
51 | * NOTE: URCU_TLS() is NOT async-signal-safe, you can't use it | |
52 | * inside any function which can be called from signal handler. | |
53 | * | |
54 | * But if pthread_getspecific() is async-signal-safe in your | |
55 | * platform, you can make URCU_TLS() async-signal-safe via: | |
56 | * ensuring the first call to URCU_TLS() of a given TLS variable of | |
57 | * all threads is called earliest from a non-signal handler function. | |
58 | * | |
59 | * Example: In any thread, the first call of URCU_TLS(rcu_reader) | |
60 | * is called from rcu_register_thread(), so we can ensure all later | |
61 | * URCU_TLS(rcu_reader) in any thread is async-signal-safe. | |
9948a988 MD |
62 | * |
63 | * Moreover, URCU_TLS variables should not be touched from signal | |
64 | * handlers setup with with sigaltstack(2). | |
c85e62f3 LJ |
65 | */ |
66 | ||
4d0d66bb | 67 | # define DECLARE_URCU_TLS(type, name) \ |
3db1417f | 68 | CONFIG_RCU_TLS type name |
4d0d66bb MD |
69 | |
70 | # define DEFINE_URCU_TLS(type, name) \ | |
3db1417f | 71 | CONFIG_RCU_TLS type name |
4d0d66bb | 72 | |
1745be1a MD |
73 | # define __DEFINE_URCU_TLS_GLOBAL(type, name) \ |
74 | CONFIG_RCU_TLS type name | |
75 | ||
3db1417f | 76 | # define URCU_TLS(name) (name) |
4d0d66bb MD |
77 | |
78 | #else /* #ifndef CONFIG_RCU_TLS */ | |
79 | ||
26836791 MD |
80 | /* |
81 | * The *_1() macros ensure macro parameters are expanded. | |
1745be1a MD |
82 | * |
83 | * __DEFINE_URCU_TLS_GLOBAL and __URCU_TLS_CALL exist for the sole | |
84 | * purpose of notifying applications compiled against non-fixed 0.7 and | |
85 | * 0.8 userspace RCU headers and using multiple flavors concurrently to | |
86 | * recompile against fixed userspace RCU headers. | |
26836791 MD |
87 | */ |
88 | ||
4d0d66bb MD |
89 | # include <pthread.h> |
90 | ||
91 | struct urcu_tls { | |
92 | pthread_key_t key; | |
93 | pthread_mutex_t init_mutex; | |
94 | int init_done; | |
95 | }; | |
96 | ||
26836791 | 97 | # define DECLARE_URCU_TLS_1(type, name) \ |
1745be1a MD |
98 | type *__tls_access2_ ## name(void) |
99 | ||
26836791 MD |
100 | # define DECLARE_URCU_TLS(type, name) \ |
101 | DECLARE_URCU_TLS_1(type, name) | |
4d0d66bb MD |
102 | |
103 | /* | |
104 | * Note: we don't free memory at process exit, since it will be dealt | |
105 | * with by the OS. | |
106 | */ | |
1745be1a MD |
107 | # define __URCU_TLS_CALL_1(name) \ |
108 | __tls_access2_ ## name | |
109 | ||
110 | # define __URCU_TLS_CALL(name) \ | |
111 | __URCU_TLS_CALL_1(name) | |
112 | ||
26836791 | 113 | # define DEFINE_URCU_TLS_1(type, name) \ |
1745be1a | 114 | type *__tls_access2_ ## name(void) \ |
4d0d66bb MD |
115 | { \ |
116 | static struct urcu_tls __tls_ ## name = { \ | |
117 | .init_mutex = PTHREAD_MUTEX_INITIALIZER,\ | |
118 | .init_done = 0, \ | |
119 | }; \ | |
120 | void *__tls_p; \ | |
121 | if (!__tls_ ## name.init_done) { \ | |
122 | /* Mutex to protect concurrent init */ \ | |
123 | pthread_mutex_lock(&__tls_ ## name.init_mutex); \ | |
124 | if (!__tls_ ## name.init_done) { \ | |
125 | (void) pthread_key_create(&__tls_ ## name.key, \ | |
126 | free); \ | |
127 | cmm_smp_wmb(); /* create key before write init_done */ \ | |
128 | __tls_ ## name.init_done = 1; \ | |
129 | } \ | |
130 | pthread_mutex_unlock(&__tls_ ## name.init_mutex); \ | |
131 | } \ | |
132 | cmm_smp_rmb(); /* read init_done before getting key */ \ | |
133 | __tls_p = pthread_getspecific(__tls_ ## name.key); \ | |
134 | if (caa_unlikely(__tls_p == NULL)) { \ | |
135 | __tls_p = calloc(1, sizeof(type)); \ | |
136 | (void) pthread_setspecific(__tls_ ## name.key, \ | |
137 | __tls_p); \ | |
138 | } \ | |
139 | return __tls_p; \ | |
140 | } | |
141 | ||
1745be1a MD |
142 | /* |
143 | * Define with an without macro expansion to handle erroneous callers. | |
144 | * Trigger an abort() if the caller application uses the clashing symbol | |
145 | * if a weak symbol is overridden. | |
146 | */ | |
147 | # define __DEFINE_URCU_TLS_GLOBAL(type, name) \ | |
148 | DEFINE_URCU_TLS_1(type, name) \ | |
149 | int __urcu_tls_symbol_refcount_ ## name __attribute__((weak)); \ | |
150 | static __attribute__((constructor)) \ | |
151 | void __urcu_tls_inc_refcount_ ## name(void) \ | |
152 | { \ | |
153 | __urcu_tls_symbol_refcount_ ## name++; \ | |
154 | } \ | |
155 | type *__tls_access_ ## name(void) \ | |
156 | { \ | |
157 | if (__urcu_tls_symbol_refcount_ ## name > 1) { \ | |
158 | fprintf(stderr, "Error: Userspace RCU symbol clash for multiple concurrent flavors. Please upgrade liburcu libraries and headers, then recompile your application.\n"); \ | |
159 | abort(); \ | |
160 | } \ | |
161 | return __URCU_TLS_CALL(name)(); \ | |
162 | } | |
163 | ||
26836791 MD |
164 | # define DEFINE_URCU_TLS(type, name) \ |
165 | DEFINE_URCU_TLS_1(type, name) | |
166 | ||
1745be1a | 167 | # define URCU_TLS_1(name) (*__tls_access2_ ## name()) |
26836791 MD |
168 | |
169 | # define URCU_TLS(name) URCU_TLS_1(name) | |
4d0d66bb MD |
170 | |
171 | #endif /* #else #ifndef CONFIG_RCU_TLS */ | |
172 | ||
173 | #ifdef __cplusplus | |
174 | } | |
175 | #endif | |
176 | ||
177 | #endif /* _URCU_TLS_COMPAT_H */ |