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John Stultz87de5ac2010-09-20 17:42:46 -07001/*
John Stultz1f5a2472010-12-09 12:02:18 -08002 * Generic Timer-queue
John Stultz87de5ac2010-09-20 17:42:46 -07003 *
John Stultz1f5a2472010-12-09 12:02:18 -08004 * Manages a simple queue of timers, ordered by expiration time.
John Stultz87de5ac2010-09-20 17:42:46 -07005 * 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
John Stultz1f5a2472010-12-09 12:02:18 -080025#include <linux/timerqueue.h>
John Stultz87de5ac2010-09-20 17:42:46 -070026#include <linux/rbtree.h>
John Stultz9bb99b12010-12-06 13:32:12 -080027#include <linux/module.h>
John Stultz87de5ac2010-09-20 17:42:46 -070028
29/**
John Stultz1f5a2472010-12-09 12:02:18 -080030 * timerqueue_add - Adds timer to timerqueue.
John Stultz87de5ac2010-09-20 17:42:46 -070031 *
John Stultz1f5a2472010-12-09 12:02:18 -080032 * @head: head of timerqueue
John Stultz87de5ac2010-09-20 17:42:46 -070033 * @node: timer node to be added
34 *
John Stultz1f5a2472010-12-09 12:02:18 -080035 * Adds the timer node to the timerqueue, sorted by the
John Stultz87de5ac2010-09-20 17:42:46 -070036 * node's expires value.
37 */
John Stultz1f5a2472010-12-09 12:02:18 -080038void timerqueue_add(struct timerqueue_head *head, struct timerqueue_node *node)
John Stultz87de5ac2010-09-20 17:42:46 -070039{
40 struct rb_node **p = &head->head.rb_node;
41 struct rb_node *parent = NULL;
John Stultz1f5a2472010-12-09 12:02:18 -080042 struct timerqueue_node *ptr;
John Stultz87de5ac2010-09-20 17:42:46 -070043
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;
John Stultz1f5a2472010-12-09 12:02:18 -080049 ptr = rb_entry(parent, struct timerqueue_node, node);
John Stultz87de5ac2010-09-20 17:42:46 -070050 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}
John Stultz9bb99b12010-12-06 13:32:12 -080061EXPORT_SYMBOL_GPL(timerqueue_add);
John Stultz87de5ac2010-09-20 17:42:46 -070062
63/**
John Stultz1f5a2472010-12-09 12:02:18 -080064 * timerqueue_del - Removes a timer from the timerqueue.
John Stultz87de5ac2010-09-20 17:42:46 -070065 *
John Stultz1f5a2472010-12-09 12:02:18 -080066 * @head: head of timerqueue
John Stultz87de5ac2010-09-20 17:42:46 -070067 * @node: timer node to be removed
68 *
John Stultz1f5a2472010-12-09 12:02:18 -080069 * Removes the timer node from the timerqueue.
John Stultz87de5ac2010-09-20 17:42:46 -070070 */
John Stultz1f5a2472010-12-09 12:02:18 -080071void timerqueue_del(struct timerqueue_head *head, struct timerqueue_node *node)
John Stultz87de5ac2010-09-20 17:42:46 -070072{
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 ?
John Stultz1f5a2472010-12-09 12:02:18 -080080 rb_entry(rbn, struct timerqueue_node, node) : NULL;
John Stultz87de5ac2010-09-20 17:42:46 -070081 }
82 rb_erase(&node->node, &head->head);
83 RB_CLEAR_NODE(&node->node);
84}
John Stultz9bb99b12010-12-06 13:32:12 -080085EXPORT_SYMBOL_GPL(timerqueue_del);
John Stultz87de5ac2010-09-20 17:42:46 -070086
87/**
John Stultz1f5a2472010-12-09 12:02:18 -080088 * timerqueue_iterate_next - Returns the timer after the provided timer
John Stultz87de5ac2010-09-20 17:42:46 -070089 *
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 */
John Stultz1f5a2472010-12-09 12:02:18 -080096struct timerqueue_node *timerqueue_iterate_next(struct timerqueue_node *node)
John Stultz87de5ac2010-09-20 17:42:46 -070097{
98 struct rb_node *next;
99
100 if (!node)
101 return NULL;
102 next = rb_next(&node->node);
103 if (!next)
104 return NULL;
John Stultz1f5a2472010-12-09 12:02:18 -0800105 return container_of(next, struct timerqueue_node, node);
John Stultz87de5ac2010-09-20 17:42:46 -0700106}
John Stultz9bb99b12010-12-06 13:32:12 -0800107EXPORT_SYMBOL_GPL(timerqueue_iterate_next);