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87de5ac7 JS |
1 | /* |
2 | * Generic Timer-list | |
3 | * | |
4 | * Manages a simple list 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/timerlist.h> | |
26 | #include <linux/rbtree.h> | |
27 | ||
28 | /** | |
29 | * timerlist_add - Adds timer to timerlist. | |
30 | * | |
31 | * @head: head of timerlist | |
32 | * @node: timer node to be added | |
33 | * | |
34 | * Adds the timer node to the timerlist, sorted by the | |
35 | * node's expires value. | |
36 | */ | |
37 | void timerlist_add(struct timerlist_head *head, struct timerlist_node *node) | |
38 | { | |
39 | struct rb_node **p = &head->head.rb_node; | |
40 | struct rb_node *parent = NULL; | |
41 | struct timerlist_node *ptr; | |
42 | ||
43 | /* Make sure we don't add nodes that are already added */ | |
44 | WARN_ON_ONCE(!RB_EMPTY_NODE(&node->node)); | |
45 | ||
46 | while (*p) { | |
47 | parent = *p; | |
48 | ptr = rb_entry(parent, struct timerlist_node, node); | |
49 | if (node->expires.tv64 < ptr->expires.tv64) | |
50 | p = &(*p)->rb_left; | |
51 | else | |
52 | p = &(*p)->rb_right; | |
53 | } | |
54 | rb_link_node(&node->node, parent, p); | |
55 | rb_insert_color(&node->node, &head->head); | |
56 | ||
57 | if (!head->next || node->expires.tv64 < head->next->expires.tv64) | |
58 | head->next = node; | |
59 | } | |
60 | ||
61 | /** | |
62 | * timerlist_del - Removes a timer from the timerlist. | |
63 | * | |
64 | * @head: head of timerlist | |
65 | * @node: timer node to be removed | |
66 | * | |
67 | * Removes the timer node from the timerlist. | |
68 | */ | |
69 | void timerlist_del(struct timerlist_head *head, struct timerlist_node *node) | |
70 | { | |
71 | WARN_ON_ONCE(RB_EMPTY_NODE(&node->node)); | |
72 | ||
73 | /* update next pointer */ | |
74 | if (head->next == node) { | |
75 | struct rb_node *rbn = rb_next(&node->node); | |
76 | ||
77 | head->next = rbn ? | |
78 | rb_entry(rbn, struct timerlist_node, node) : NULL; | |
79 | } | |
80 | rb_erase(&node->node, &head->head); | |
81 | RB_CLEAR_NODE(&node->node); | |
82 | } | |
83 | ||
84 | ||
85 | /** | |
86 | * timerlist_getnext - Returns the timer with the earlies expiration time | |
87 | * | |
88 | * @head: head of timerlist | |
89 | * | |
90 | * Returns a pointer to the timer node that has the | |
91 | * earliest expiration time. | |
92 | */ | |
93 | struct timerlist_node *timerlist_getnext(struct timerlist_head *head) | |
94 | { | |
95 | return head->next; | |
96 | } | |
97 | ||
98 | ||
99 | /** | |
100 | * timerlist_iterate_next - Returns the timer after the provided timer | |
101 | * | |
102 | * @node: Pointer to a timer. | |
103 | * | |
104 | * Provides the timer that is after the given node. This is used, when | |
105 | * necessary, to iterate through the list of timers in a timer list | |
106 | * without modifying the list. | |
107 | */ | |
108 | struct timerlist_node *timerlist_iterate_next(struct timerlist_node *node) | |
109 | { | |
110 | struct rb_node *next; | |
111 | ||
112 | if (!node) | |
113 | return NULL; | |
114 | next = rb_next(&node->node); | |
115 | if (!next) | |
116 | return NULL; | |
117 | return container_of(next, struct timerlist_node, node); | |
118 | } |