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1 | /* |
2 | * Generic Timer-queue |
3 | * |
4 | * Manages a simple queue of timers, ordered by expiration time. |
5 | * Uses rbtrees for quick list adds and expiration. |
6 | * |
7 | * NOTE: All of the following functions need to be serialized |
8 | * to avoid races. No locking is done by this libary code. |
9 | * |
10 | * This program is free software; you can redistribute it and/or modify |
11 | * it under the terms of the GNU General Public License as published by |
12 | * the Free Software Foundation; either version 2 of the License, or |
13 | * (at your option) any later version. |
14 | * |
15 | * This program is distributed in the hope that it will be useful, |
16 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
17 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
18 | * GNU General Public License for more details. |
19 | * |
20 | * You should have received a copy of the GNU General Public License |
21 | * along with this program; if not, write to the Free Software |
22 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
23 | */ |
24 | |
25 | #include <linux/timerqueue.h> |
26 | #include <linux/rbtree.h> |
27 | #include <linux/module.h> |
28 | |
29 | /** |
30 | * timerqueue_add - Adds timer to timerqueue. |
31 | * |
32 | * @head: head of timerqueue |
33 | * @node: timer node to be added |
34 | * |
35 | * Adds the timer node to the timerqueue, sorted by the |
36 | * node's expires value. |
37 | */ |
38 | void timerqueue_add(struct timerqueue_head *head, struct timerqueue_node *node) |
39 | { |
40 | struct rb_node **p = &head->head.rb_node; |
41 | struct rb_node *parent = NULL; |
42 | struct timerqueue_node *ptr; |
43 | |
44 | /* Make sure we don't add nodes that are already added */ |
45 | WARN_ON_ONCE(!RB_EMPTY_NODE(&node->node)); |
46 | |
47 | while (*p) { |
48 | parent = *p; |
49 | ptr = rb_entry(parent, struct timerqueue_node, node); |
50 | if (node->expires.tv64 < ptr->expires.tv64) |
51 | p = &(*p)->rb_left; |
52 | else |
53 | p = &(*p)->rb_right; |
54 | } |
55 | rb_link_node(&node->node, parent, p); |
56 | rb_insert_color(&node->node, &head->head); |
57 | |
58 | if (!head->next || node->expires.tv64 < head->next->expires.tv64) |
59 | head->next = node; |
60 | } |
61 | EXPORT_SYMBOL_GPL(timerqueue_add); |
62 | |
63 | /** |
64 | * timerqueue_del - Removes a timer from the timerqueue. |
65 | * |
66 | * @head: head of timerqueue |
67 | * @node: timer node to be removed |
68 | * |
69 | * Removes the timer node from the timerqueue. |
70 | */ |
71 | void timerqueue_del(struct timerqueue_head *head, struct timerqueue_node *node) |
72 | { |
73 | WARN_ON_ONCE(RB_EMPTY_NODE(&node->node)); |
74 | |
75 | /* update next pointer */ |
76 | if (head->next == node) { |
77 | struct rb_node *rbn = rb_next(&node->node); |
78 | |
79 | head->next = rbn ? |
80 | rb_entry(rbn, struct timerqueue_node, node) : NULL; |
81 | } |
82 | rb_erase(&node->node, &head->head); |
83 | RB_CLEAR_NODE(&node->node); |
84 | } |
85 | EXPORT_SYMBOL_GPL(timerqueue_del); |
86 | |
87 | /** |
88 | * timerqueue_iterate_next - Returns the timer after the provided timer |
89 | * |
90 | * @node: Pointer to a timer. |
91 | * |
92 | * Provides the timer that is after the given node. This is used, when |
93 | * necessary, to iterate through the list of timers in a timer list |
94 | * without modifying the list. |
95 | */ |
96 | struct timerqueue_node *timerqueue_iterate_next(struct timerqueue_node *node) |
97 | { |
98 | struct rb_node *next; |
99 | |
100 | if (!node) |
101 | return NULL; |
102 | next = rb_next(&node->node); |
103 | if (!next) |
104 | return NULL; |
105 | return container_of(next, struct timerqueue_node, node); |
106 | } |
107 | EXPORT_SYMBOL_GPL(timerqueue_iterate_next); |
108 |
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