seccomp: add cacheflush to whitelist
[qemu/ar7.git] / include / qemu / rcu.h
blobf6d1d56375d9618f81f542b69b2a3155d5aff6a0
1 #ifndef QEMU_RCU_H
2 #define QEMU_RCU_H
4 /*
5 * urcu-mb.h
7 * Userspace RCU header with explicit memory barrier.
9 * This library is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU Lesser General Public
11 * License as published by the Free Software Foundation; either
12 * version 2.1 of the License, or (at your option) any later version.
14 * This library is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17 * Lesser General Public License for more details.
19 * You should have received a copy of the GNU Lesser General Public
20 * License along with this library; if not, write to the Free Software
21 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
23 * IBM's contributions to this file may be relicensed under LGPLv2 or later.
26 #include <stdlib.h>
27 #include <assert.h>
28 #include <limits.h>
29 #include <unistd.h>
30 #include <stdint.h>
31 #include <stdbool.h>
32 #include <glib.h>
34 #include "qemu/compiler.h"
35 #include "qemu/thread.h"
36 #include "qemu/queue.h"
37 #include "qemu/atomic.h"
39 #ifdef __cplusplus
40 extern "C" {
41 #endif
44 * Important !
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.
51 #ifdef DEBUG_RCU
52 #define rcu_assert(args...) assert(args)
53 #else
54 #define rcu_assert(args...)
55 #endif
58 * Global quiescent period counter with low-order bits unused.
59 * Using a int rather than a char to eliminate false register dependencies
60 * causing stalls on some architectures.
62 extern unsigned long rcu_gp_ctr;
64 extern QemuEvent rcu_gp_event;
66 struct rcu_reader_data {
67 /* Data used by both reader and synchronize_rcu() */
68 unsigned long ctr;
69 bool waiting;
71 /* Data used by reader only */
72 unsigned depth;
74 /* Data used for registry, protected by rcu_registry_lock */
75 QLIST_ENTRY(rcu_reader_data) node;
78 extern __thread struct rcu_reader_data rcu_reader;
80 static inline void rcu_read_lock(void)
82 struct rcu_reader_data *p_rcu_reader = &rcu_reader;
83 unsigned ctr;
85 if (p_rcu_reader->depth++ > 0) {
86 return;
89 ctr = atomic_read(&rcu_gp_ctr);
90 atomic_xchg(&p_rcu_reader->ctr, ctr);
91 if (atomic_read(&p_rcu_reader->waiting)) {
92 atomic_set(&p_rcu_reader->waiting, false);
93 qemu_event_set(&rcu_gp_event);
97 static inline void rcu_read_unlock(void)
99 struct rcu_reader_data *p_rcu_reader = &rcu_reader;
101 assert(p_rcu_reader->depth != 0);
102 if (--p_rcu_reader->depth > 0) {
103 return;
106 atomic_xchg(&p_rcu_reader->ctr, 0);
107 if (atomic_read(&p_rcu_reader->waiting)) {
108 atomic_set(&p_rcu_reader->waiting, false);
109 qemu_event_set(&rcu_gp_event);
113 extern void synchronize_rcu(void);
116 * Reader thread registration.
118 extern void rcu_register_thread(void);
119 extern void rcu_unregister_thread(void);
120 extern void rcu_after_fork(void);
122 struct rcu_head;
123 typedef void RCUCBFunc(struct rcu_head *head);
125 struct rcu_head {
126 struct rcu_head *next;
127 RCUCBFunc *func;
130 extern void call_rcu1(struct rcu_head *head, RCUCBFunc *func);
132 /* The operands of the minus operator must have the same type,
133 * which must be the one that we specify in the cast.
135 #define call_rcu(head, func, field) \
136 call_rcu1(({ \
137 char __attribute__((unused)) \
138 offset_must_be_zero[-offsetof(typeof(*(head)), field)], \
139 func_type_invalid = (func) - (void (*)(typeof(head)))(func); \
140 &(head)->field; \
141 }), \
142 (RCUCBFunc *)(func))
144 #define g_free_rcu(obj, field) \
145 call_rcu1(({ \
146 char __attribute__((unused)) \
147 offset_must_be_zero[-offsetof(typeof(*(obj)), field)]; \
148 &(obj)->field; \
149 }), \
150 (RCUCBFunc *)g_free);
152 #ifdef __cplusplus
154 #endif
156 #endif /* QEMU_RCU_H */