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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 */
39void 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}
62EXPORT_SYMBOL_GPL(timerqueue_add);
63
64/**
65 * timerqueue_del - Removes a timer from the timerqueue.
66 *
67 * @head: head of timerqueue
68 * @node: timer node to be removed
69 *
70 * Removes the timer node from the timerqueue.
71 */
72void timerqueue_del(struct timerqueue_head *head, struct timerqueue_node *node)
73{
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 ?
81 rb_entry(rbn, struct timerqueue_node, node) : NULL;
82 }
83 rb_erase(&node->node, &head->head);
84 RB_CLEAR_NODE(&node->node);
85}
86EXPORT_SYMBOL_GPL(timerqueue_del);
87
88/**
89 * timerqueue_iterate_next - Returns the timer after the provided timer
90 *
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 */
97struct timerqueue_node *timerqueue_iterate_next(struct timerqueue_node *node)
98{
99 struct rb_node *next;
100
101 if (!node)
102 return NULL;
103 next = rb_next(&node->node);
104 if (!next)
105 return NULL;
106 return container_of(next, struct timerqueue_node, node);
107}
108EXPORT_SYMBOL_GPL(timerqueue_iterate_next);
1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Generic Timer-queue
4 *
5 * Manages a simple queue of timers, ordered by expiration time.
6 * Uses rbtrees for quick list adds and expiration.
7 *
8 * NOTE: All of the following functions need to be serialized
9 * to avoid races. No locking is done by this library code.
10 */
11
12#include <linux/bug.h>
13#include <linux/timerqueue.h>
14#include <linux/rbtree.h>
15#include <linux/export.h>
16
17/**
18 * timerqueue_add - Adds timer to timerqueue.
19 *
20 * @head: head of timerqueue
21 * @node: timer node to be added
22 *
23 * Adds the timer node to the timerqueue, sorted by the node's expires
24 * value. Returns true if the newly added timer is the first expiring timer in
25 * the queue.
26 */
27bool timerqueue_add(struct timerqueue_head *head, struct timerqueue_node *node)
28{
29 struct rb_node **p = &head->rb_root.rb_root.rb_node;
30 struct rb_node *parent = NULL;
31 struct timerqueue_node *ptr;
32 bool leftmost = true;
33
34 /* Make sure we don't add nodes that are already added */
35 WARN_ON_ONCE(!RB_EMPTY_NODE(&node->node));
36
37 while (*p) {
38 parent = *p;
39 ptr = rb_entry(parent, struct timerqueue_node, node);
40 if (node->expires < ptr->expires) {
41 p = &(*p)->rb_left;
42 } else {
43 p = &(*p)->rb_right;
44 leftmost = false;
45 }
46 }
47 rb_link_node(&node->node, parent, p);
48 rb_insert_color_cached(&node->node, &head->rb_root, leftmost);
49
50 return leftmost;
51}
52EXPORT_SYMBOL_GPL(timerqueue_add);
53
54/**
55 * timerqueue_del - Removes a timer from the timerqueue.
56 *
57 * @head: head of timerqueue
58 * @node: timer node to be removed
59 *
60 * Removes the timer node from the timerqueue. Returns true if the queue is
61 * not empty after the remove.
62 */
63bool timerqueue_del(struct timerqueue_head *head, struct timerqueue_node *node)
64{
65 WARN_ON_ONCE(RB_EMPTY_NODE(&node->node));
66
67 rb_erase_cached(&node->node, &head->rb_root);
68 RB_CLEAR_NODE(&node->node);
69
70 return !RB_EMPTY_ROOT(&head->rb_root.rb_root);
71}
72EXPORT_SYMBOL_GPL(timerqueue_del);
73
74/**
75 * timerqueue_iterate_next - Returns the timer after the provided timer
76 *
77 * @node: Pointer to a timer.
78 *
79 * Provides the timer that is after the given node. This is used, when
80 * necessary, to iterate through the list of timers in a timer list
81 * without modifying the list.
82 */
83struct timerqueue_node *timerqueue_iterate_next(struct timerqueue_node *node)
84{
85 struct rb_node *next;
86
87 if (!node)
88 return NULL;
89 next = rb_next(&node->node);
90 if (!next)
91 return NULL;
92 return container_of(next, struct timerqueue_node, node);
93}
94EXPORT_SYMBOL_GPL(timerqueue_iterate_next);