Provide pthread_atfork-friendly interfaces
[urcu.git] / urcu-qsbr.h
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1#ifndef _URCU_QSBR_H
2#define _URCU_QSBR_H
3
4/*
7ac06cef 5 * urcu-qsbr.h
420e5b92 6 *
7ac06cef 7 * Userspace RCU QSBR header.
420e5b92 8 *
7ac06cef 9 * LGPL-compatible code should include this header with :
420e5b92 10 *
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11 * #define _LGPL_SOURCE
12 * #include <urcu.h>
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13 *
14 * This library is free software; you can redistribute it and/or
15 * modify it under the terms of the GNU Lesser General Public
16 * License as published by the Free Software Foundation; either
17 * version 2.1 of the License, or (at your option) any later version.
18 *
19 * This library is distributed in the hope that it will be useful,
20 * but WITHOUT ANY WARRANTY; without even the implied warranty of
21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
22 * Lesser General Public License for more details.
23 *
24 * You should have received a copy of the GNU Lesser General Public
25 * License along with this library; if not, write to the Free Software
26 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
27 *
28 * IBM's contributions to this file may be relicensed under LGPLv2 or later.
29 */
30
31#include <stdlib.h>
32#include <pthread.h>
420e5b92 33
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34/*
35 * See urcu-pointer.h and urcu-pointer-static.h for pointer publication headers.
36 */
37#include <urcu-pointer.h>
38
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39#ifdef __cplusplus
40extern "C" {
41#endif
42
420e5b92 43/*
7ac06cef 44 * Important !
420e5b92 45 *
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46 * Each thread containing read-side critical sections must be registered
47 * with rcu_register_thread() before calling rcu_read_lock().
48 * rcu_unregister_thread() should be called before the thread exits.
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49 */
50
7ac06cef 51#ifdef _LGPL_SOURCE
420e5b92 52
7ac06cef 53#include <urcu-qsbr-static.h>
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54
55/*
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56 * Mappings for static use of the userspace RCU library.
57 * Should only be used in LGPL-compatible code.
420e5b92 58 */
420e5b92 59
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60/*
61 * rcu_read_lock()
62 * rcu_read_unlock()
63 *
64 * Mark the beginning and end of a read-side critical section.
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65 * DON'T FORGET TO USE rcu_register_thread/rcu_unregister_thread() FOR EACH
66 * THREAD WITH READ-SIDE CRITICAL SECTION.
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67 */
68#define rcu_read_lock() _rcu_read_lock()
69#define rcu_read_unlock() _rcu_read_unlock()
420e5b92 70
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71#define rcu_quiescent_state() _rcu_quiescent_state()
72#define rcu_thread_offline() _rcu_thread_offline()
73#define rcu_thread_online() _rcu_thread_online()
420e5b92 74
7ac06cef 75#else /* !_LGPL_SOURCE */
420e5b92 76
420e5b92 77/*
7ac06cef 78 * library wrappers to be used by non-LGPL compatible source code.
420e5b92 79 */
420e5b92 80
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81/*
82 * QSBR read lock/unlock are guaranteed to be no-ops. Therefore, we expose them
83 * in the LGPL header for any code to use. However, the debug version is not
84 * nops and may contain sanity checks. To activate it, applications must be
02be5561 85 * recompiled with -DRCU_DEBUG (even non-LGPL/GPL applications). This is the
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86 * best trade-off between license/performance/code triviality and
87 * library debugging & tracing features we could come up with.
88 */
89
02be5561 90#if (!defined(BUILD_QSBR_LIB) && defined(RCU_DEBUG))
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91
92static inline void rcu_read_lock(void)
93{
94}
95
96static inline void rcu_read_lock(void)
97{
98}
99
02be5561 100#else /* !RCU_DEBUG */
727f819d 101
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102extern void rcu_read_lock(void);
103extern void rcu_read_unlock(void);
420e5b92 104
02be5561 105#endif /* !RCU_DEBUG */
727f819d 106
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107extern void rcu_quiescent_state(void);
108extern void rcu_thread_offline(void);
109extern void rcu_thread_online(void);
420e5b92 110
7ac06cef 111#endif /* !_LGPL_SOURCE */
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112
113extern void synchronize_rcu(void);
114
115/*
116 * Reader thread registration.
117 */
118extern void rcu_register_thread(void);
119extern void rcu_unregister_thread(void);
120
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121#ifdef __cplusplus
122}
123#endif
124
420e5b92 125#endif /* _URCU_QSBR_H */
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