blob: 0d54bcbc8170c7754aef0487eb10b8f7b5773103 [file] [log] [blame]
* Generic Timer-queue
* Manages a simple queue of timers, ordered by expiration time.
* Uses rbtrees for quick list adds and expiration.
* NOTE: All of the following functions need to be serialized
* to avoid races. No locking is done by this library code.
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* GNU General Public License for more details.
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
#include <linux/bug.h>
#include <linux/timerqueue.h>
#include <linux/rbtree.h>
#include <linux/export.h>
* timerqueue_add - Adds timer to timerqueue.
* @head: head of timerqueue
* @node: timer node to be added
* Adds the timer node to the timerqueue, sorted by the node's expires
* value. Returns true if the newly added timer is the first expiring timer in
* the queue.
bool timerqueue_add(struct timerqueue_head *head, struct timerqueue_node *node)
struct rb_node **p = &head->head.rb_node;
struct rb_node *parent = NULL;
struct timerqueue_node *ptr;
/* Make sure we don't add nodes that are already added */
while (*p) {
parent = *p;
ptr = rb_entry(parent, struct timerqueue_node, node);
if (node->expires < ptr->expires)
p = &(*p)->rb_left;
p = &(*p)->rb_right;
rb_link_node(&node->node, parent, p);
rb_insert_color(&node->node, &head->head);
if (!head->next || node->expires < head->next->expires) {
head->next = node;
return true;
return false;
* timerqueue_del - Removes a timer from the timerqueue.
* @head: head of timerqueue
* @node: timer node to be removed
* Removes the timer node from the timerqueue. Returns true if the queue is
* not empty after the remove.
bool timerqueue_del(struct timerqueue_head *head, struct timerqueue_node *node)
/* update next pointer */
if (head->next == node) {
struct rb_node *rbn = rb_next(&node->node);
head->next = rb_entry_safe(rbn, struct timerqueue_node, node);
rb_erase(&node->node, &head->head);
return head->next != NULL;
* timerqueue_iterate_next - Returns the timer after the provided timer
* @node: Pointer to a timer.
* Provides the timer that is after the given node. This is used, when
* necessary, to iterate through the list of timers in a timer list
* without modifying the list.
struct timerqueue_node *timerqueue_iterate_next(struct timerqueue_node *node)
struct rb_node *next;
if (!node)
return NULL;
next = rb_next(&node->node);
if (!next)
return NULL;
return container_of(next, struct timerqueue_node, node);