1#include <linux/rcupdate.h>
 2#include <pthread.h>
 3#include <stdio.h>
 4#include <assert.h>
 5
 6static pthread_mutex_t rculock = PTHREAD_MUTEX_INITIALIZER;
 7static struct rcu_head *rcuhead_global = NULL;
 8static __thread int nr_rcuhead = 0;
 9static __thread struct rcu_head *rcuhead = NULL;
10static __thread struct rcu_head *rcutail = NULL;
11
12static pthread_cond_t rcu_worker_cond = PTHREAD_COND_INITIALIZER;
13
14/* switch to urcu implementation when it is merged. */
15void call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *head))
16{
17	head->func = func;
18	head->next = rcuhead;
19	rcuhead = head;
20	if (!rcutail)
21		rcutail = head;
22	nr_rcuhead++;
23	if (nr_rcuhead >= 1000) {
24		int signal = 0;
25
26		pthread_mutex_lock(&rculock);
27		if (!rcuhead_global)
28			signal = 1;
29		rcutail->next = rcuhead_global;
30		rcuhead_global = head;
31		pthread_mutex_unlock(&rculock);
32
33		nr_rcuhead = 0;
34		rcuhead = NULL;
35		rcutail = NULL;
36
37		if (signal) {
38			pthread_cond_signal(&rcu_worker_cond);
39		}
40	}
41}
42
43static void *rcu_worker(void *arg)
44{
45	struct rcu_head *r;
46
47	rcupdate_thread_init();
48
49	while (1) {
50		pthread_mutex_lock(&rculock);
51		while (!rcuhead_global) {
52			pthread_cond_wait(&rcu_worker_cond, &rculock);
53		}
54		r = rcuhead_global;
55		rcuhead_global = NULL;
56
57		pthread_mutex_unlock(&rculock);
58
59		synchronize_rcu();
60
61		while (r) {
62			struct rcu_head *tmp = r->next;
63			r->func(r);
64			r = tmp;
65		}
66	}
67
68	rcupdate_thread_exit();
69
70	return NULL;
71}
72
73static pthread_t worker_thread;
74void rcupdate_init(void)
75{
76	pthread_create(&worker_thread, NULL, rcu_worker, NULL);
77}
78
79void rcupdate_thread_init(void)
80{
81	rcu_register_thread();
82}
83void rcupdate_thread_exit(void)
84{
85	rcu_unregister_thread();
86}