add missing comment to wfstack.c
[urcu.git] / urcu-pointer.h
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1#ifndef _URCU_POINTER_H
2#define _URCU_POINTER_H
3
4/*
5 * urcu-pointer.h
6 *
7 * Userspace RCU header. Operations on pointers.
8 *
6982d6d7 9 * Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
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10 * Copyright (c) 2009 Paul E. McKenney, IBM Corporation.
11 *
12 * This library is free software; you can redistribute it and/or
13 * modify it under the terms of the GNU Lesser General Public
14 * License as published by the Free Software Foundation; either
15 * version 2.1 of the License, or (at your option) any later version.
16 *
17 * This library is distributed in the hope that it will be useful,
18 * but WITHOUT ANY WARRANTY; without even the implied warranty of
19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
20 * Lesser General Public License for more details.
21 *
22 * You should have received a copy of the GNU Lesser General Public
23 * License along with this library; if not, write to the Free Software
24 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
25 *
26 * IBM's contributions to this file may be relicensed under LGPLv2 or later.
27 */
28
29#include <urcu/compiler.h>
30#include <urcu/arch.h>
48d848c7 31#include <urcu/uatomic_arch.h>
7e30abe3 32
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33#ifdef __cplusplus
34extern "C" {
35#endif
36
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37#ifdef _LGPL_SOURCE
38
39#include <urcu-pointer-static.h>
40
41/*
42 * rcu_dereference(ptr)
43 *
44 * Fetch a RCU-protected pointer. Typically used to copy the variable ptr to a
45 * local variable.
46 */
47#define rcu_dereference _rcu_dereference
48
49/*
50 * rcu_cmpxchg_pointer(type **ptr, type *new, type *old)
51 * type *rcu_xchg_pointer(type **ptr, type *new)
52 * type *rcu_set_pointer(type **ptr, type *new)
53 *
54 * RCU pointer updates.
55 * @ptr: address of the pointer to modify
56 * @new: new pointer value
57 * @old: old pointer value (expected)
58 *
59 * return: old pointer value
60 */
61#define rcu_cmpxchg_pointer _rcu_cmpxchg_pointer
62#define rcu_xchg_pointer _rcu_xchg_pointer
63#define rcu_set_pointer _rcu_set_pointer
64
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65#else /* !_LGPL_SOURCE */
66
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67extern void *rcu_dereference_sym(void *p);
68#define rcu_dereference(p) \
69 ({ \
70 typeof(p) _________p1 = \
71 rcu_dereference_sym((void *)(p)); \
72 (_________p1); \
73 })
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74
75extern void *rcu_cmpxchg_pointer_sym(void **p, void *old, void *_new);
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76#define rcu_cmpxchg_pointer(p, old, _new) \
77 ({ \
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78 typeof(*p) _________pold = (old); \
79 typeof(*p) _________pnew = (_new); \
2ff1db4a 80 typeof(*p) _________p1 = \
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81 rcu_cmpxchg_pointer_sym((void **)(p), _________pold, \
82 _________pnew); \
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83 (_________p1); \
84 })
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85
86extern void *rcu_xchg_pointer_sym(void **p, void *v);
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87#define rcu_xchg_pointer(p, v) \
88 ({ \
2b5554c9 89 typeof(*p) _________pv = (v); \
2ff1db4a 90 typeof(*p) _________p1 = \
2b5554c9 91 rcu_xchg_pointer_sym((void **)(p), _________pv); \
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92 (_________p1); \
93 })
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94
95extern void *rcu_set_pointer_sym(void **p, void *v);
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96#define rcu_set_pointer(p, v) \
97 ({ \
2b5554c9 98 typeof(*p) _________pv = (v); \
2ff1db4a 99 typeof(*p) _________p1 = \
2b5554c9 100 rcu_set_pointer_sym((void **)(p), _________pv); \
2ff1db4a 101 })
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102
103#endif /* !_LGPL_SOURCE */
104
105/*
106 * rcu_assign_pointer(type *ptr, type *new)
107 *
108 * Same as rcu_set_pointer, but takes the pointer to assign to rather than its
109 * address as first parameter. Provided for compatibility with the Linux kernel
110 * RCU semantic.
111 */
112#define rcu_assign_pointer(p, v) rcu_set_pointer((&p), (v))
113
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114#ifdef __cplusplus
115}
116#endif
117
7e30abe3 118#endif /* _URCU_POINTER_H */
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