Merge remote branch 'origin/urcu/ht' into urcu/ht
[urcu.git] / urcu / static / rculfstack.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.h>
30 /* A urcu implementation header should be already included. */
31
32 #ifdef __cplusplus
33 extern "C" {
34 #endif
35
36 static inline
37 void _cds_lfs_node_init_rcu(struct cds_lfs_node_rcu *node)
38 {
39 }
40
41 static inline
42 void _cds_lfs_init_rcu(struct cds_lfs_stack_rcu *s)
43 {
44 s->head = NULL;
45 }
46
47 static inline
48 void _cds_lfs_push_rcu(struct cds_lfs_stack_rcu *s, struct cds_lfs_node_rcu *node)
49 {
50 struct cds_lfs_node_rcu *head = NULL;
51
52 for (;;) {
53 struct cds_lfs_node_rcu *old_head = head;
54
55 node->next = head;
56 /*
57 * uatomic_cmpxchg() implicit memory barrier orders earlier
58 * stores to node before publication.
59 */
60 head = uatomic_cmpxchg(&s->head, old_head, node);
61 if (old_head == head)
62 break;
63 }
64 }
65
66 /*
67 * Should be called under rcu read-side lock.
68 *
69 * The caller must wait for a grace period to pass before freeing the returned
70 * node or modifying the cds_lfs_node_rcu structure.
71 * Returns NULL if stack is empty.
72 */
73 static inline
74 struct cds_lfs_node_rcu *
75 _cds_lfs_pop_rcu(struct cds_lfs_stack_rcu *s)
76 {
77 for (;;) {
78 struct cds_lfs_node_rcu *head;
79
80 head = rcu_dereference(s->head);
81 if (head) {
82 struct cds_lfs_node_rcu *next = rcu_dereference(head->next);
83
84 if (uatomic_cmpxchg(&s->head, head, next) == head) {
85 return head;
86 } else {
87 /* Concurrent modification. Retry. */
88 continue;
89 }
90 } else {
91 /* Empty stack */
92 return NULL;
93 }
94 }
95 }
96
97 #ifdef __cplusplus
98 }
99 #endif
100
101 #endif /* _URCU_RCULFSTACK_STATIC_H */
This page took 0.032782 seconds and 5 git commands to generate.