Commit | Line | Data |
---|---|---|
474190bf MD |
1 | /* |
2 | * Copyright (C) 2013 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
3 | * | |
4 | * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED | |
5 | * OR IMPLIED. ANY USE IS AT YOUR OWN RISK. | |
6 | * | |
7 | * Permission is hereby granted to use or copy this program for any | |
8 | * purpose, provided the above notices are retained on all copies. | |
9 | * Permission to modify the code and to distribute modified code is | |
10 | * granted, provided the above notices are retained, and a notice that | |
11 | * the code was modified is included with the above copyright notice. | |
12 | * | |
13 | * This example shows how to do a non-circular RCU linked list | |
14 | * traversal, safely against concurrent RCU updates. | |
15 | * cds_hlist_for_each_rcu() iterates on struct cds_hlist_node, and thus, | |
16 | * either caa_container_of() or cds_hlist_entry() are needed to access | |
17 | * the container structure. | |
18 | */ | |
19 | ||
20 | #include <stdio.h> | |
21 | ||
b9050d91 | 22 | #include <urcu/urcu-memb.h> /* Userspace RCU flavor */ |
474190bf MD |
23 | #include <urcu/rcuhlist.h> /* RCU hlist */ |
24 | #include <urcu/compiler.h> /* For CAA_ARRAY_SIZE */ | |
25 | ||
26 | /* | |
27 | * Nodes populated into the list. | |
28 | */ | |
29 | struct mynode { | |
30 | int value; /* Node content */ | |
31 | struct cds_hlist_node node; /* Linked-list chaining */ | |
32 | }; | |
33 | ||
34 | int main(int argc, char **argv) | |
35 | { | |
36 | int values[] = { -5, 42, 36, 24, }; | |
37 | CDS_HLIST_HEAD(mylist); /* Defines an empty hlist head */ | |
38 | unsigned int i; | |
39 | int ret = 0; | |
40 | struct cds_hlist_node *pos; | |
41 | ||
42 | /* | |
43 | * Each thread need using RCU read-side need to be explicitly | |
44 | * registered. | |
45 | */ | |
b9050d91 | 46 | urcu_memb_register_thread(); |
474190bf MD |
47 | |
48 | /* | |
49 | * Adding nodes to the linked-list. Safe against concurrent | |
50 | * RCU traversals, require mutual exclusion with list updates. | |
51 | */ | |
52 | for (i = 0; i < CAA_ARRAY_SIZE(values); i++) { | |
53 | struct mynode *node; | |
54 | ||
55 | node = malloc(sizeof(*node)); | |
56 | if (!node) { | |
57 | ret = -1; | |
58 | goto end; | |
59 | } | |
60 | node->value = values[i]; | |
61 | cds_hlist_add_head_rcu(&node->node, &mylist); | |
62 | } | |
63 | ||
64 | /* | |
65 | * RCU-safe iteration on the list. | |
66 | */ | |
67 | printf("mylist content:"); | |
68 | ||
69 | /* | |
70 | * Surround the RCU read-side critical section with rcu_read_lock() | |
71 | * and rcu_read_unlock(). | |
72 | */ | |
b9050d91 | 73 | urcu_memb_read_lock(); |
474190bf MD |
74 | |
75 | /* | |
76 | * This traversal can be performed concurrently with RCU | |
77 | * updates. | |
78 | */ | |
79 | cds_hlist_for_each_rcu(pos, &mylist) { | |
80 | struct mynode *node = cds_hlist_entry(pos, struct mynode, node); | |
81 | ||
82 | printf(" %d", node->value); | |
83 | } | |
84 | ||
b9050d91 | 85 | urcu_memb_read_unlock(); |
474190bf MD |
86 | |
87 | printf("\n"); | |
88 | end: | |
b9050d91 | 89 | urcu_memb_unregister_thread(); |
474190bf MD |
90 | return ret; |
91 | } |