blob: 782ae8ca2c06f2b3439b10592cef6a43c31223cd
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 library 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/bug.h> |
26 | #include <linux/timerqueue.h> |
27 | #include <linux/rbtree.h> |
28 | #include <linux/export.h> |
29 | |
30 | /** |
31 | * timerqueue_add - Adds timer to timerqueue. |
32 | * |
33 | * @head: head of timerqueue |
34 | * @node: timer node to be added |
35 | * |
36 | * Adds the timer node to the timerqueue, sorted by the |
37 | * node's expires value. |
38 | */ |
39 | bool timerqueue_add(struct timerqueue_head *head, struct timerqueue_node *node) |
40 | { |
41 | struct rb_node **p = &head->head.rb_node; |
42 | struct rb_node *parent = NULL; |
43 | struct timerqueue_node *ptr; |
44 | |
45 | /* Make sure we don't add nodes that are already added */ |
46 | WARN_ON_ONCE(!RB_EMPTY_NODE(&node->node)); |
47 | |
48 | while (*p) { |
49 | parent = *p; |
50 | ptr = rb_entry(parent, struct timerqueue_node, node); |
51 | if (node->expires.tv64 < ptr->expires.tv64) |
52 | p = &(*p)->rb_left; |
53 | else |
54 | p = &(*p)->rb_right; |
55 | } |
56 | rb_link_node(&node->node, parent, p); |
57 | rb_insert_color(&node->node, &head->head); |
58 | |
59 | if (!head->next || node->expires.tv64 < head->next->expires.tv64) { |
60 | head->next = node; |
61 | return true; |
62 | } |
63 | return false; |
64 | } |
65 | EXPORT_SYMBOL_GPL(timerqueue_add); |
66 | |
67 | /** |
68 | * timerqueue_del - Removes a timer from the timerqueue. |
69 | * |
70 | * @head: head of timerqueue |
71 | * @node: timer node to be removed |
72 | * |
73 | * Removes the timer node from the timerqueue. |
74 | */ |
75 | bool timerqueue_del(struct timerqueue_head *head, struct timerqueue_node *node) |
76 | { |
77 | WARN_ON_ONCE(RB_EMPTY_NODE(&node->node)); |
78 | |
79 | /* update next pointer */ |
80 | if (head->next == node) { |
81 | struct rb_node *rbn = rb_next(&node->node); |
82 | |
83 | head->next = rbn ? |
84 | rb_entry(rbn, struct timerqueue_node, node) : NULL; |
85 | } |
86 | rb_erase(&node->node, &head->head); |
87 | RB_CLEAR_NODE(&node->node); |
88 | return head->next != NULL; |
89 | } |
90 | EXPORT_SYMBOL_GPL(timerqueue_del); |
91 | |
92 | /** |
93 | * timerqueue_iterate_next - Returns the timer after the provided timer |
94 | * |
95 | * @node: Pointer to a timer. |
96 | * |
97 | * Provides the timer that is after the given node. This is used, when |
98 | * necessary, to iterate through the list of timers in a timer list |
99 | * without modifying the list. |
100 | */ |
101 | struct timerqueue_node *timerqueue_iterate_next(struct timerqueue_node *node) |
102 | { |
103 | struct rb_node *next; |
104 | |
105 | if (!node) |
106 | return NULL; |
107 | next = rb_next(&node->node); |
108 | if (!next) |
109 | return NULL; |
110 | return container_of(next, struct timerqueue_node, node); |
111 | } |
112 | EXPORT_SYMBOL_GPL(timerqueue_iterate_next); |
113 |