projects / urcu.git / blame
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| b6a37eac MD |
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 */ |