2 * Copyright (C) 2013 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
4 * This library is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Lesser General Public
6 * License as published by the Free Software Foundation; either
7 * version 2.1 of the License, or (at your option) any later version.
9 * This library is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * Lesser General Public License for more details.
14 * You should have received a copy of the GNU Lesser General Public
15 * License along with this library; if not, write to the Free Software
16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 #include <urcu-qsbr.h>
21 #include <urcu/rculist.h>
22 #include <urcu/compiler.h>
30 * This is a mock-up example where updates and RCU traversals are
31 * performed by the same thread to keep things simple on purpose.
34 static CDS_LIST_HEAD(mylist
);
38 struct cds_list_head node
; /* linked-list chaining */
39 struct rcu_head rcu_head
; /* for call_rcu() */
43 int add_node(uint64_t v
)
47 node
= calloc(sizeof(*node
), 1);
51 cds_list_add_rcu(&node
->node
, &mylist
);
55 void rcu_free_node(struct rcu_head
*rh
)
57 struct mynode
*node
= caa_container_of(rh
, struct mynode
, rcu_head
);
62 int main(int argc
, char **argv
)
64 uint64_t values
[] = { 42, 36, 24, };
67 struct mynode
*node
, *n
;
70 * Each thread need using RCU read-side need to be explicitely
73 rcu_register_thread();
76 * Adding nodes to the linked-list. Safe against concurrent
77 * RCU traversals, require mutual exclusion with list updates.
79 for (i
= 0; i
< CAA_ARRAY_SIZE(values
); i
++) {
80 ret
= add_node(values
[i
]);
86 * For all RCU flavors except QSBR, we need to explicitly mark
87 * RCU read-side critical sections with rcu_read_lock() and
88 * rcu_read_unlock(). They can be nested. Those are no-ops for
94 * RCU traversal of the linked list.
96 cds_list_for_each_entry_rcu(node
, &mylist
, node
) {
97 printf("Value: %" PRIu64
"\n", node
->value
);
102 * Removing nodes from linked list. Safe against concurrent RCU
103 * traversals, require mutual exclusion with list updates.
105 cds_list_for_each_entry_safe(node
, n
, &mylist
, node
) {
106 cds_list_del_rcu(&node
->node
);
107 call_rcu(&node
->rcu_head
, rcu_free_node
);
111 * For QSBR flavor, we need to explicitly announce quiescent
114 rcu_quiescent_state();
117 * For QSBR flavor, when a thread needs to be in a quiescent
118 * state for a long period of time, we use rcu_thread_offline()
119 * and rcu_thread_online().
121 rcu_thread_offline();
128 * Waiting for previously called call_rcu handlers to complete
129 * before program exits is a good practice.
134 rcu_unregister_thread();
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