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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 _rcu_lfs_node_init(struct rcu_lfs_node *node) | |
37 | { | |
38 | } | |
39 | ||
40 | void _rcu_lfs_init(struct rcu_lfs_stack *s) | |
41 | { | |
42 | s->head = NULL; | |
43 | } | |
44 | ||
45 | void _rcu_lfs_push(struct rcu_lfs_stack *s, struct rcu_lfs_node *node) | |
46 | { | |
47 | for (;;) { | |
48 | struct rcu_lfs_node *head; | |
49 | ||
50 | rcu_read_lock(); | |
51 | head = rcu_dereference(s->head); | |
52 | node->next = head; | |
53 | /* | |
54 | * uatomic_cmpxchg() implicit memory barrier orders earlier | |
55 | * stores to node before publication. | |
56 | */ | |
57 | if (uatomic_cmpxchg(&s->head, head, node) == head) { | |
58 | rcu_read_unlock(); | |
59 | return; | |
60 | } else { | |
61 | /* Failure to prepend. Retry. */ | |
62 | rcu_read_unlock(); | |
63 | continue; | |
64 | } | |
65 | } | |
66 | } | |
67 | ||
68 | /* | |
69 | * The caller must wait for a grace period to pass before freeing the returned | |
70 | * node or modifying the rcu_lfs_node structure. | |
71 | * Returns NULL if stack is empty. | |
72 | */ | |
73 | struct rcu_lfs_node * | |
74 | _rcu_lfs_pop(struct rcu_lfs_stack *s) | |
75 | { | |
76 | for (;;) { | |
77 | struct rcu_lfs_node *head; | |
78 | ||
79 | rcu_read_lock(); | |
80 | head = rcu_dereference(s->head); | |
81 | if (head) { | |
82 | struct rcu_lfs_node *next = rcu_dereference(head->next); | |
83 | ||
84 | if (uatomic_cmpxchg(&s->head, head, next) == head) { | |
85 | rcu_read_unlock(); | |
86 | return head; | |
87 | } else { | |
88 | /* Concurrent modification. Retry. */ | |
89 | rcu_read_unlock(); | |
90 | continue; | |
91 | } | |
92 | } else { | |
93 | /* Empty stack */ | |
94 | rcu_read_unlock(); | |
95 | return NULL; | |
96 | } | |
97 | } | |
98 | } | |
99 | ||
100 | #ifdef __cplusplus | |
101 | } | |
102 | #endif | |
103 | ||
104 | #endif /* _URCU_RCULFSTACK_STATIC_H */ |