rcutorture: make goflag volatile
[urcu.git] / urcu / rculfstack-static.h
1 #ifndef _URCU_RCULFSTACK_STATIC_H
2 #define _URCU_RCULFSTACK_STATIC_H
3
4 /*
5 * rculfstack-static.h
6 *
7 * Userspace RCU library - Lock-Free RCU Stack
8 *
9 * Copyright 2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
10 *
11 * TO BE INCLUDED ONLY IN LGPL-COMPATIBLE CODE. See rculfstack.h for linking
12 * dynamically with the userspace rcu library.
13 *
14 * This library is free software; you can redistribute it and/or
15 * modify it under the terms of the GNU Lesser General Public
16 * License as published by the Free Software Foundation; either
17 * version 2.1 of the License, or (at your option) any later version.
18 *
19 * This library is distributed in the hope that it will be useful,
20 * but WITHOUT ANY WARRANTY; without even the implied warranty of
21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
22 * Lesser General Public License for more details.
23 *
24 * You should have received a copy of the GNU Lesser General Public
25 * License along with this library; if not, write to the Free Software
26 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
27 */
28
29 #include <urcu/uatomic_arch.h>
30 /* A urcu implementation header should be already included. */
31
32 #ifdef __cplusplus
33 extern "C" {
34 #endif
35
36 void _cds_lfs_node_init_rcu(struct cds_lfs_node_rcu *node)
37 {
38 }
39
40 void _cds_lfs_init_rcu(struct cds_lfs_stack_rcu *s)
41 {
42 s->head = NULL;
43 }
44
45 void _cds_lfs_push_rcu(struct cds_lfs_stack_rcu *s, struct cds_lfs_node_rcu *node)
46 {
47 struct cds_lfs_node_rcu *head = NULL;
48
49 for (;;) {
50 struct cds_lfs_node_rcu *old_head = head;
51
52 node->next = head;
53 /*
54 * uatomic_cmpxchg() implicit memory barrier orders earlier
55 * stores to node before publication.
56 */
57 head = uatomic_cmpxchg(&s->head, old_head, node);
58 if (old_head == head)
59 break;
60 }
61 }
62
63 /*
64 * The caller must wait for a grace period to pass before freeing the returned
65 * node or modifying the cds_lfs_node_rcu structure.
66 * Returns NULL if stack is empty.
67 */
68 struct cds_lfs_node_rcu *
69 _cds_lfs_pop_rcu(struct cds_lfs_stack_rcu *s)
70 {
71 for (;;) {
72 struct cds_lfs_node_rcu *head;
73
74 rcu_read_lock();
75 head = rcu_dereference(s->head);
76 if (head) {
77 struct cds_lfs_node_rcu *next = rcu_dereference(head->next);
78
79 if (uatomic_cmpxchg(&s->head, head, next) == head) {
80 rcu_read_unlock();
81 return head;
82 } else {
83 /* Concurrent modification. Retry. */
84 rcu_read_unlock();
85 continue;
86 }
87 } else {
88 /* Empty stack */
89 rcu_read_unlock();
90 return NULL;
91 }
92 }
93 }
94
95 #ifdef __cplusplus
96 }
97 #endif
98
99 #endif /* _URCU_RCULFSTACK_STATIC_H */
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