rculfhash: introduce cds_lfht_node_init_deleted
[urcu.git] / include / urcu / tls-compat.h
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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
32extern "C" {
33#endif
34
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35#ifdef CONFIG_RCU_TLS
36
e915ab84 37/*
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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)
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46# define URCU_TLS_STORAGE_CLASS __declspec(thread)
47#else
48# define URCU_TLS_STORAGE_CLASS __thread
49#endif
4d0d66bb 50
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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:
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62 * typedef void (*call_rcu_flavor)(struct rcu_head *, XXXX);
63 * DECLARE_URCU_TLS(call_rcu_flavor, p_call_rcu);
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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.
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76 *
77 * Moreover, URCU_TLS variables should not be touched from signal
78 * handlers setup with with sigaltstack(2).
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79 */
80
4d0d66bb 81# define DECLARE_URCU_TLS(type, name) \
109267f6 82 URCU_TLS_STORAGE_CLASS type name
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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)
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91
92#else /* #ifndef CONFIG_RCU_TLS */
93
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94/*
95 * The *_1() macros ensure macro parameters are expanded.
96 */
97
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98# include <pthread.h>
99
100struct 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)
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108# define DECLARE_URCU_TLS(type, name) \
109 DECLARE_URCU_TLS_1(type, name)
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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) \
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116 type *__tls_access_ ## name(void) \
117 { \
118 static struct urcu_tls __tls_ ## name = { \
69fbb39e 119 .key = 0, \
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120 .init_mutex = PTHREAD_MUTEX_INITIALIZER,\
121 .init_done = 0, \
122 }; \
cb1f3ebf 123 __typeof__(type) *__tls_p; \
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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 \
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140 (void) pthread_setspecific(__tls_ ## name.key, \
141 __tls_p); \
142 } \
143 return __tls_p; \
144 }
145
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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 */)
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154
155# define URCU_TLS_1(name) (*__tls_access_ ## name())
156
157# define URCU_TLS(name) URCU_TLS_1(name)
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158
159#endif /* #else #ifndef CONFIG_RCU_TLS */
160
161#ifdef __cplusplus
162}
163#endif
164
165#endif /* _URCU_TLS_COMPAT_H */
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