]> git.proxmox.com Git - mirror_ubuntu-artful-kernel.git/blame - lib/timerqueue.c
Merge tag 'sound-4.12-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai...
[mirror_ubuntu-artful-kernel.git] / lib / timerqueue.c
CommitLineData
87de5ac7 1/*
1f5a2479 2 * Generic Timer-queue
87de5ac7 3 *
1f5a2479 4 * Manages a simple queue of timers, ordered by expiration time.
87de5ac7
JS
5 * Uses rbtrees for quick list adds and expiration.
6 *
7 * NOTE: All of the following functions need to be serialized
25985edc 8 * to avoid races. No locking is done by this library code.
87de5ac7
JS
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
50af5ead 25#include <linux/bug.h>
1f5a2479 26#include <linux/timerqueue.h>
87de5ac7 27#include <linux/rbtree.h>
8bc3bcc9 28#include <linux/export.h>
87de5ac7
JS
29
30/**
1f5a2479 31 * timerqueue_add - Adds timer to timerqueue.
87de5ac7 32 *
1f5a2479 33 * @head: head of timerqueue
87de5ac7
JS
34 * @node: timer node to be added
35 *
1f5a2479 36 * Adds the timer node to the timerqueue, sorted by the
87de5ac7
JS
37 * node's expires value.
38 */
c320642e 39bool timerqueue_add(struct timerqueue_head *head, struct timerqueue_node *node)
87de5ac7
JS
40{
41 struct rb_node **p = &head->head.rb_node;
42 struct rb_node *parent = NULL;
1f5a2479 43 struct timerqueue_node *ptr;
87de5ac7
JS
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;
1f5a2479 50 ptr = rb_entry(parent, struct timerqueue_node, node);
2456e855 51 if (node->expires < ptr->expires)
87de5ac7
JS
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
2456e855 59 if (!head->next || node->expires < head->next->expires) {
87de5ac7 60 head->next = node;
c320642e
TG
61 return true;
62 }
63 return false;
87de5ac7 64}
9bb99b14 65EXPORT_SYMBOL_GPL(timerqueue_add);
87de5ac7
JS
66
67/**
1f5a2479 68 * timerqueue_del - Removes a timer from the timerqueue.
87de5ac7 69 *
1f5a2479 70 * @head: head of timerqueue
87de5ac7
JS
71 * @node: timer node to be removed
72 *
1f5a2479 73 * Removes the timer node from the timerqueue.
87de5ac7 74 */
c320642e 75bool timerqueue_del(struct timerqueue_head *head, struct timerqueue_node *node)
87de5ac7
JS
76{
77 WARN_ON_ONCE(RB_EMPTY_NODE(&node->node));
78
79 /* update next pointer */
80 if (head->next == node) {
81 struct rb_node *rbn = rb_next(&node->node);
82
d852d394 83 head->next = rb_entry_safe(rbn, struct timerqueue_node, node);
87de5ac7
JS
84 }
85 rb_erase(&node->node, &head->head);
86 RB_CLEAR_NODE(&node->node);
c320642e 87 return head->next != NULL;
87de5ac7 88}
9bb99b14 89EXPORT_SYMBOL_GPL(timerqueue_del);
87de5ac7 90
87de5ac7 91/**
1f5a2479 92 * timerqueue_iterate_next - Returns the timer after the provided timer
87de5ac7
JS
93 *
94 * @node: Pointer to a timer.
95 *
96 * Provides the timer that is after the given node. This is used, when
97 * necessary, to iterate through the list of timers in a timer list
98 * without modifying the list.
99 */
1f5a2479 100struct timerqueue_node *timerqueue_iterate_next(struct timerqueue_node *node)
87de5ac7
JS
101{
102 struct rb_node *next;
103
104 if (!node)
105 return NULL;
106 next = rb_next(&node->node);
107 if (!next)
108 return NULL;
1f5a2479 109 return container_of(next, struct timerqueue_node, node);
87de5ac7 110}
9bb99b14 111EXPORT_SYMBOL_GPL(timerqueue_iterate_next);