Root/lib/timerqueue.c

Source at commit b386be689295730688885552666ea40b2e639b14 created 8 years 11 months ago.
By Maarten ter Huurne, Revert "MIPS: JZ4740: reset: Initialize hibernate wakeup counters."
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/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 */
38void 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}
61EXPORT_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 */
71void 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}
85EXPORT_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 */
96struct 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}
107EXPORT_SYMBOL_GPL(timerqueue_iterate_next);
108

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