/* *  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 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the *  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. */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 */	WARN_ON_ONCE(!RB_EMPTY_NODE(&node->node)); 	while (*p) {		parent = *p;		ptr = rb_entry(parent, struct timerqueue_node, node);		if (node->expires < ptr->expires)			p = &(*p)->rb_left;		else			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;}EXPORT_SYMBOL_GPL(timerqueue_add); /** * 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. */bool timerqueue_del(struct timerqueue_head *head, struct timerqueue_node *node){	WARN_ON_ONCE(RB_EMPTY_NODE(&node->node)); 	/* update next pointer */	if (head->next == node) {		struct rb_node *rbn = rb_next(&node->node); 		head->next = rbn ?			rb_entry(rbn, struct timerqueue_node, node) : NULL;	}	rb_erase(&node->node, &head->head);	RB_CLEAR_NODE(&node->node);	return head->next != NULL;}EXPORT_SYMBOL_GPL(timerqueue_del); /** * 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);}EXPORT_SYMBOL_GPL(timerqueue_iterate_next);