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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
Lucas De Marchi25985ed2011-03-30 22:57:33 -03008 * to avoid races. No locking is done by this library code.
John Stultz87de5ac2010-09-20 17:42:46 -07009 *
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
Paul Gortmaker50af5ea2012-01-20 18:35:53 -050025#include <linux/bug.h>
John Stultz1f5a2472010-12-09 12:02:18 -080026#include <linux/timerqueue.h>
John Stultz87de5ac2010-09-20 17:42:46 -070027#include <linux/rbtree.h>
Paul Gortmaker8bc3bcc2011-11-16 21:29:17 -050028#include <linux/export.h>
John Stultz87de5ac2010-09-20 17:42:46 -070029
30/**
John Stultz1f5a2472010-12-09 12:02:18 -080031 * timerqueue_add - Adds timer to timerqueue.
John Stultz87de5ac2010-09-20 17:42:46 -070032 *
John Stultz1f5a2472010-12-09 12:02:18 -080033 * @head: head of timerqueue
John Stultz87de5ac2010-09-20 17:42:46 -070034 * @node: timer node to be added
35 *
John Stultz1f5a2472010-12-09 12:02:18 -080036 * Adds the timer node to the timerqueue, sorted by the
John Stultz87de5ac2010-09-20 17:42:46 -070037 * node's expires value.
38 */
John Stultz1f5a2472010-12-09 12:02:18 -080039void timerqueue_add(struct timerqueue_head *head, struct timerqueue_node *node)
John Stultz87de5ac2010-09-20 17:42:46 -070040{
41 struct rb_node **p = &head->head.rb_node;
42 struct rb_node *parent = NULL;
John Stultz1f5a2472010-12-09 12:02:18 -080043 struct timerqueue_node *ptr;
John Stultz87de5ac2010-09-20 17:42:46 -070044
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;
John Stultz1f5a2472010-12-09 12:02:18 -080050 ptr = rb_entry(parent, struct timerqueue_node, node);
John Stultz87de5ac2010-09-20 17:42:46 -070051 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}
John Stultz9bb99b12010-12-06 13:32:12 -080062EXPORT_SYMBOL_GPL(timerqueue_add);
John Stultz87de5ac2010-09-20 17:42:46 -070063
64/**
John Stultz1f5a2472010-12-09 12:02:18 -080065 * timerqueue_del - Removes a timer from the timerqueue.
John Stultz87de5ac2010-09-20 17:42:46 -070066 *
John Stultz1f5a2472010-12-09 12:02:18 -080067 * @head: head of timerqueue
John Stultz87de5ac2010-09-20 17:42:46 -070068 * @node: timer node to be removed
69 *
John Stultz1f5a2472010-12-09 12:02:18 -080070 * Removes the timer node from the timerqueue.
John Stultz87de5ac2010-09-20 17:42:46 -070071 */
John Stultz1f5a2472010-12-09 12:02:18 -080072void timerqueue_del(struct timerqueue_head *head, struct timerqueue_node *node)
John Stultz87de5ac2010-09-20 17:42:46 -070073{
74 WARN_ON_ONCE(RB_EMPTY_NODE(&node->node));
75
76 /* update next pointer */
77 if (head->next == node) {
78 struct rb_node *rbn = rb_next(&node->node);
79
80 head->next = rbn ?
John Stultz1f5a2472010-12-09 12:02:18 -080081 rb_entry(rbn, struct timerqueue_node, node) : NULL;
John Stultz87de5ac2010-09-20 17:42:46 -070082 }
83 rb_erase(&node->node, &head->head);
84 RB_CLEAR_NODE(&node->node);
85}
John Stultz9bb99b12010-12-06 13:32:12 -080086EXPORT_SYMBOL_GPL(timerqueue_del);
John Stultz87de5ac2010-09-20 17:42:46 -070087
88/**
John Stultz1f5a2472010-12-09 12:02:18 -080089 * timerqueue_iterate_next - Returns the timer after the provided timer
John Stultz87de5ac2010-09-20 17:42:46 -070090 *
91 * @node: Pointer to a timer.
92 *
93 * Provides the timer that is after the given node. This is used, when
94 * necessary, to iterate through the list of timers in a timer list
95 * without modifying the list.
96 */
John Stultz1f5a2472010-12-09 12:02:18 -080097struct timerqueue_node *timerqueue_iterate_next(struct timerqueue_node *node)
John Stultz87de5ac2010-09-20 17:42:46 -070098{
99 struct rb_node *next;
100
101 if (!node)
102 return NULL;
103 next = rb_next(&node->node);
104 if (!next)
105 return NULL;
John Stultz1f5a2472010-12-09 12:02:18 -0800106 return container_of(next, struct timerqueue_node, node);
John Stultz87de5ac2010-09-20 17:42:46 -0700107}
John Stultz9bb99b12010-12-06 13:32:12 -0800108EXPORT_SYMBOL_GPL(timerqueue_iterate_next);