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- // 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);
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