4 * Manages a simple queue of timers, ordered by expiration time.
5 * Uses rbtrees for quick list adds and expiration.
7 * NOTE: All of the following functions need to be serialized
8 * to avoid races. No locking is done by this library code.
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.
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.
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
25 #include <linux/bug.h>
26 #include <linux/timerqueue.h>
27 #include <linux/rbtree.h>
28 #include <linux/export.h>
31 * timerqueue_add - Adds timer to timerqueue.
33 * @head: head of timerqueue
34 * @node: timer node to be added
36 * Adds the timer node to the timerqueue, sorted by the
37 * node's expires value.
39 bool timerqueue_add(struct timerqueue_head *head, struct timerqueue_node *node)
41 struct rb_node **p = &head->head.rb_node;
42 struct rb_node *parent = NULL;
43 struct timerqueue_node *ptr;
45 /* Make sure we don't add nodes that are already added */
46 WARN_ON_ONCE(!RB_EMPTY_NODE(&node->node));
50 ptr = rb_entry(parent, struct timerqueue_node, node);
51 if (node->expires < ptr->expires)
56 rb_link_node(&node->node, parent, p);
57 rb_insert_color(&node->node, &head->head);
59 if (!head->next || node->expires < head->next->expires) {
65 EXPORT_SYMBOL_GPL(timerqueue_add);
68 * timerqueue_del - Removes a timer from the timerqueue.
70 * @head: head of timerqueue
71 * @node: timer node to be removed
73 * Removes the timer node from the timerqueue.
75 bool timerqueue_del(struct timerqueue_head *head, struct timerqueue_node *node)
77 WARN_ON_ONCE(RB_EMPTY_NODE(&node->node));
79 /* update next pointer */
80 if (head->next == node) {
81 struct rb_node *rbn = rb_next(&node->node);
84 rb_entry(rbn, struct timerqueue_node, node) : NULL;
86 rb_erase(&node->node, &head->head);
87 RB_CLEAR_NODE(&node->node);
88 return head->next != NULL;
90 EXPORT_SYMBOL_GPL(timerqueue_del);
93 * timerqueue_iterate_next - Returns the timer after the provided timer
95 * @node: Pointer to a timer.
97 * Provides the timer that is after the given node. This is used, when
98 * necessary, to iterate through the list of timers in a timer list
99 * without modifying the list.
101 struct timerqueue_node *timerqueue_iterate_next(struct timerqueue_node *node)
103 struct rb_node *next;
107 next = rb_next(&node->node);
110 return container_of(next, struct timerqueue_node, node);
112 EXPORT_SYMBOL_GPL(timerqueue_iterate_next);