1#ifndef QEMU_RCU_H
2#define QEMU_RCU_H
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27#include "qemu/thread.h"
28#include "qemu/queue.h"
29#include "qemu/atomic.h"
30#include "qemu/sys_membarrier.h"
31
32#ifdef __cplusplus
33extern "C" {
34#endif
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43
44#ifdef DEBUG_RCU
45#define rcu_assert(args...) assert(args)
46#else
47#define rcu_assert(args...)
48#endif
49
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54
55extern unsigned long rcu_gp_ctr;
56
57extern QemuEvent rcu_gp_event;
58
59struct rcu_reader_data {
60
61 unsigned long ctr;
62 bool waiting;
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64
65 unsigned depth;
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67
68 QLIST_ENTRY(rcu_reader_data) node;
69};
70
71extern __thread struct rcu_reader_data rcu_reader;
72
73static inline void rcu_read_lock(void)
74{
75 struct rcu_reader_data *p_rcu_reader = &rcu_reader;
76 unsigned ctr;
77
78 if (p_rcu_reader->depth++ > 0) {
79 return;
80 }
81
82 ctr = atomic_read(&rcu_gp_ctr);
83 atomic_set(&p_rcu_reader->ctr, ctr);
84
85
86 smp_mb_placeholder();
87}
88
89static inline void rcu_read_unlock(void)
90{
91 struct rcu_reader_data *p_rcu_reader = &rcu_reader;
92
93 assert(p_rcu_reader->depth != 0);
94 if (--p_rcu_reader->depth > 0) {
95 return;
96 }
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103 atomic_store_release(&p_rcu_reader->ctr, 0);
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105
106 smp_mb_placeholder();
107 if (unlikely(atomic_read(&p_rcu_reader->waiting))) {
108 atomic_set(&p_rcu_reader->waiting, false);
109 qemu_event_set(&rcu_gp_event);
110 }
111}
112
113extern void synchronize_rcu(void);
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117
118extern void rcu_register_thread(void);
119extern void rcu_unregister_thread(void);
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123
124extern void rcu_enable_atfork(void);
125extern void rcu_disable_atfork(void);
126
127struct rcu_head;
128typedef void RCUCBFunc(struct rcu_head *head);
129
130struct rcu_head {
131 struct rcu_head *next;
132 RCUCBFunc *func;
133};
134
135extern void call_rcu1(struct rcu_head *head, RCUCBFunc *func);
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139
140#define call_rcu(head, func, field) \
141 call_rcu1(({ \
142 char __attribute__((unused)) \
143 offset_must_be_zero[-offsetof(typeof(*(head)), field)], \
144 func_type_invalid = (func) - (void (*)(typeof(head)))(func); \
145 &(head)->field; \
146 }), \
147 (RCUCBFunc *)(func))
148
149#define g_free_rcu(obj, field) \
150 call_rcu1(({ \
151 char __attribute__((unused)) \
152 offset_must_be_zero[-offsetof(typeof(*(obj)), field)]; \
153 &(obj)->field; \
154 }), \
155 (RCUCBFunc *)g_free);
156
157#ifdef __cplusplus
158}
159#endif
160
161#endif
162