// SPDX-License-Identifier: GPL-2.0-or-later/* *  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. */ #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->rb_root.rb_root.rb_node;	struct rb_node *parent = NULL;	struct timerqueue_node *ptr;	bool leftmost = true; 	/* 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;			leftmost = false;		}	}	rb_link_node(&node->node, parent, p);	rb_insert_color_cached(&node->node, &head->rb_root, leftmost); 	return leftmost;}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. Returns true if the queue is * not empty after the remove. */bool timerqueue_del(struct timerqueue_head *head, struct timerqueue_node *node){	WARN_ON_ONCE(RB_EMPTY_NODE(&node->node)); 	rb_erase_cached(&node->node, &head->rb_root);	RB_CLEAR_NODE(&node->node); 	return !RB_EMPTY_ROOT(&head->rb_root.rb_root);}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);