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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 | ||
109267f6 MD |
35 | #ifdef CONFIG_RCU_TLS |
36 | ||
e915ab84 | 37 | /* |
2e359284 MJ |
38 | * Default to '__thread' on all C and C++ compilers except MSVC. While C11 has |
39 | * '_Thread_local' and C++11 has 'thread_local', only '__thread' seems to have | |
40 | * a compatible implementation when linking public extern symbols across | |
41 | * language boundaries. | |
42 | * | |
43 | * For more details, see 'https://gcc.gnu.org/onlinedocs/gcc/Thread-Local.html'. | |
e915ab84 | 44 | */ |
2e359284 | 45 | #if defined(_MSC_VER) |
109267f6 MD |
46 | # define URCU_TLS_STORAGE_CLASS __declspec(thread) |
47 | #else | |
48 | # define URCU_TLS_STORAGE_CLASS __thread | |
49 | #endif | |
4d0d66bb | 50 | |
c85e62f3 LJ |
51 | /* |
52 | * Hint: How to define/declare TLS variables of compound types | |
53 | * such as array or function pointers? | |
54 | * | |
55 | * Answer: Use typedef to assign a type_name to the compound type. | |
56 | * Example: Define a TLS variable which is an int array with len=4: | |
57 | * | |
58 | * typedef int my_int_array_type[4]; | |
59 | * DEFINE_URCU_TLS(my_int_array_type, var_name); | |
60 | * | |
ffa11a18 | 61 | * Another example: |
c85e62f3 LJ |
62 | * typedef void (*call_rcu_flavor)(struct rcu_head *, XXXX); |
63 | * DECLARE_URCU_TLS(call_rcu_flavor, p_call_rcu); | |
fa320ad0 LJ |
64 | * |
65 | * NOTE: URCU_TLS() is NOT async-signal-safe, you can't use it | |
66 | * inside any function which can be called from signal handler. | |
67 | * | |
68 | * But if pthread_getspecific() is async-signal-safe in your | |
69 | * platform, you can make URCU_TLS() async-signal-safe via: | |
70 | * ensuring the first call to URCU_TLS() of a given TLS variable of | |
71 | * all threads is called earliest from a non-signal handler function. | |
72 | * | |
73 | * Example: In any thread, the first call of URCU_TLS(rcu_reader) | |
74 | * is called from rcu_register_thread(), so we can ensure all later | |
75 | * URCU_TLS(rcu_reader) in any thread is async-signal-safe. | |
9948a988 MD |
76 | * |
77 | * Moreover, URCU_TLS variables should not be touched from signal | |
78 | * handlers setup with with sigaltstack(2). | |
c85e62f3 LJ |
79 | */ |
80 | ||
4d0d66bb | 81 | # define DECLARE_URCU_TLS(type, name) \ |
109267f6 | 82 | URCU_TLS_STORAGE_CLASS type name |
4d0d66bb MD |
83 | |
84 | # define DEFINE_URCU_TLS(type, name) \ | |
109267f6 | 85 | URCU_TLS_STORAGE_CLASS type name |
4d0d66bb | 86 | |
cb1f3ebf | 87 | # define DEFINE_URCU_TLS_INIT(type, name, init) \ |
109267f6 | 88 | URCU_TLS_STORAGE_CLASS type name = (init) |
cb1f3ebf | 89 | |
3db1417f | 90 | # define URCU_TLS(name) (name) |
4d0d66bb MD |
91 | |
92 | #else /* #ifndef CONFIG_RCU_TLS */ | |
93 | ||
ae62f05a MD |
94 | /* |
95 | * The *_1() macros ensure macro parameters are expanded. | |
96 | */ | |
97 | ||
4d0d66bb MD |
98 | # include <pthread.h> |
99 | ||
100 | struct urcu_tls { | |
101 | pthread_key_t key; | |
102 | pthread_mutex_t init_mutex; | |
103 | int init_done; | |
104 | }; | |
105 | ||
ae62f05a | 106 | # define DECLARE_URCU_TLS_1(type, name) \ |
4d0d66bb | 107 | type *__tls_access_ ## name(void) |
ae62f05a MD |
108 | # define DECLARE_URCU_TLS(type, name) \ |
109 | DECLARE_URCU_TLS_1(type, name) | |
4d0d66bb MD |
110 | |
111 | /* | |
112 | * Note: we don't free memory at process exit, since it will be dealt | |
113 | * with by the OS. | |
114 | */ | |
cb1f3ebf | 115 | # define DEFINE_URCU_TLS_INIT_1(type, name, do_init) \ |
4d0d66bb MD |
116 | type *__tls_access_ ## name(void) \ |
117 | { \ | |
118 | static struct urcu_tls __tls_ ## name = { \ | |
69fbb39e | 119 | .key = 0, \ |
4d0d66bb MD |
120 | .init_mutex = PTHREAD_MUTEX_INITIALIZER,\ |
121 | .init_done = 0, \ | |
122 | }; \ | |
cb1f3ebf | 123 | __typeof__(type) *__tls_p; \ |
4d0d66bb MD |
124 | if (!__tls_ ## name.init_done) { \ |
125 | /* Mutex to protect concurrent init */ \ | |
126 | pthread_mutex_lock(&__tls_ ## name.init_mutex); \ | |
127 | if (!__tls_ ## name.init_done) { \ | |
128 | (void) pthread_key_create(&__tls_ ## name.key, \ | |
129 | free); \ | |
130 | cmm_smp_wmb(); /* create key before write init_done */ \ | |
131 | __tls_ ## name.init_done = 1; \ | |
132 | } \ | |
133 | pthread_mutex_unlock(&__tls_ ## name.init_mutex); \ | |
134 | } \ | |
135 | cmm_smp_rmb(); /* read init_done before getting key */ \ | |
69fbb39e | 136 | __tls_p = (__typeof__(type) *) pthread_getspecific(__tls_ ## name.key); \ |
4d0d66bb | 137 | if (caa_unlikely(__tls_p == NULL)) { \ |
69fbb39e | 138 | __tls_p = (__typeof__(type) *) calloc(1, sizeof(type)); \ |
cb1f3ebf | 139 | do_init \ |
4d0d66bb MD |
140 | (void) pthread_setspecific(__tls_ ## name.key, \ |
141 | __tls_p); \ | |
142 | } \ | |
143 | return __tls_p; \ | |
144 | } | |
145 | ||
cb1f3ebf MD |
146 | # define _URCU_TLS_INIT(init) \ |
147 | *__tls_p = (init); | |
148 | ||
149 | # define DEFINE_URCU_TLS_INIT(type, name, init) \ | |
150 | DEFINE_URCU_TLS_INIT_1(type, name, _URCU_TLS_INIT(init)) | |
151 | ||
ae62f05a | 152 | # define DEFINE_URCU_TLS(type, name) \ |
cb1f3ebf | 153 | DEFINE_URCU_TLS_INIT_1(type, name, /* empty */) |
ae62f05a MD |
154 | |
155 | # define URCU_TLS_1(name) (*__tls_access_ ## name()) | |
156 | ||
157 | # define URCU_TLS(name) URCU_TLS_1(name) | |
4d0d66bb MD |
158 | |
159 | #endif /* #else #ifndef CONFIG_RCU_TLS */ | |
160 | ||
161 | #ifdef __cplusplus | |
162 | } | |
163 | #endif | |
164 | ||
165 | #endif /* _URCU_TLS_COMPAT_H */ |