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12#include <linux/completion.h>
13#include <linux/interrupt.h>
14#include <linux/notifier.h>
15#include <linux/rcupdate_wait.h>
16#include <linux/kernel.h>
17#include <linux/export.h>
18#include <linux/mutex.h>
19#include <linux/sched.h>
20#include <linux/types.h>
21#include <linux/init.h>
22#include <linux/time.h>
23#include <linux/cpu.h>
24#include <linux/prefetch.h>
25#include <linux/slab.h>
26
27#include "rcu.h"
28
29
30struct rcu_ctrlblk {
31 struct rcu_head *rcucblist;
32 struct rcu_head **donetail;
33 struct rcu_head **curtail;
34};
35
36
37static struct rcu_ctrlblk rcu_ctrlblk = {
38 .donetail = &rcu_ctrlblk.rcucblist,
39 .curtail = &rcu_ctrlblk.rcucblist,
40};
41
42void rcu_barrier(void)
43{
44 wait_rcu_gp(call_rcu);
45}
46EXPORT_SYMBOL(rcu_barrier);
47
48
49void rcu_qs(void)
50{
51 unsigned long flags;
52
53 local_irq_save(flags);
54 if (rcu_ctrlblk.donetail != rcu_ctrlblk.curtail) {
55 rcu_ctrlblk.donetail = rcu_ctrlblk.curtail;
56 raise_softirq_irqoff(RCU_SOFTIRQ);
57 }
58 local_irq_restore(flags);
59}
60
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64
65
66
67void rcu_sched_clock_irq(int user)
68{
69 if (user) {
70 rcu_qs();
71 } else if (rcu_ctrlblk.donetail != rcu_ctrlblk.curtail) {
72 set_tsk_need_resched(current);
73 set_preempt_need_resched();
74 }
75}
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80
81static inline bool rcu_reclaim_tiny(struct rcu_head *head)
82{
83 rcu_callback_t f;
84 unsigned long offset = (unsigned long)head->func;
85
86 rcu_lock_acquire(&rcu_callback_map);
87 if (__is_kfree_rcu_offset(offset)) {
88 trace_rcu_invoke_kfree_callback("", head, offset);
89 kfree((void *)head - offset);
90 rcu_lock_release(&rcu_callback_map);
91 return true;
92 }
93
94 trace_rcu_invoke_callback("", head);
95 f = head->func;
96 WRITE_ONCE(head->func, (rcu_callback_t)0L);
97 f(head);
98 rcu_lock_release(&rcu_callback_map);
99 return false;
100}
101
102
103static __latent_entropy void rcu_process_callbacks(struct softirq_action *unused)
104{
105 struct rcu_head *next, *list;
106 unsigned long flags;
107
108
109 local_irq_save(flags);
110 if (rcu_ctrlblk.donetail == &rcu_ctrlblk.rcucblist) {
111
112 local_irq_restore(flags);
113 return;
114 }
115 list = rcu_ctrlblk.rcucblist;
116 rcu_ctrlblk.rcucblist = *rcu_ctrlblk.donetail;
117 *rcu_ctrlblk.donetail = NULL;
118 if (rcu_ctrlblk.curtail == rcu_ctrlblk.donetail)
119 rcu_ctrlblk.curtail = &rcu_ctrlblk.rcucblist;
120 rcu_ctrlblk.donetail = &rcu_ctrlblk.rcucblist;
121 local_irq_restore(flags);
122
123
124 while (list) {
125 next = list->next;
126 prefetch(next);
127 debug_rcu_head_unqueue(list);
128 local_bh_disable();
129 rcu_reclaim_tiny(list);
130 local_bh_enable();
131 list = next;
132 }
133}
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144
145void synchronize_rcu(void)
146{
147 RCU_LOCKDEP_WARN(lock_is_held(&rcu_bh_lock_map) ||
148 lock_is_held(&rcu_lock_map) ||
149 lock_is_held(&rcu_sched_lock_map),
150 "Illegal synchronize_rcu() in RCU read-side critical section");
151}
152EXPORT_SYMBOL_GPL(synchronize_rcu);
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158
159void call_rcu(struct rcu_head *head, rcu_callback_t func)
160{
161 unsigned long flags;
162
163 debug_rcu_head_queue(head);
164 head->func = func;
165 head->next = NULL;
166
167 local_irq_save(flags);
168 *rcu_ctrlblk.curtail = head;
169 rcu_ctrlblk.curtail = &head->next;
170 local_irq_restore(flags);
171
172 if (unlikely(is_idle_task(current))) {
173
174 resched_cpu(0);
175 }
176}
177EXPORT_SYMBOL_GPL(call_rcu);
178
179void __init rcu_init(void)
180{
181 open_softirq(RCU_SOFTIRQ, rcu_process_callbacks);
182 rcu_early_boot_tests();
183 srcu_init();
184}
185