mirror of https://gitee.com/openkylin/linux.git
85 lines
2.3 KiB
C
85 lines
2.3 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Generic Timer-queue
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*
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* Manages a simple queue of timers, ordered by expiration time.
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* Uses rbtrees for quick list adds and expiration.
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*
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* NOTE: All of the following functions need to be serialized
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* to avoid races. No locking is done by this library code.
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*/
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#include <linux/bug.h>
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#include <linux/timerqueue.h>
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#include <linux/rbtree.h>
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#include <linux/export.h>
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#define __node_2_tq(_n) \
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rb_entry((_n), struct timerqueue_node, node)
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static inline bool __timerqueue_less(struct rb_node *a, const struct rb_node *b)
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{
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return __node_2_tq(a)->expires < __node_2_tq(b)->expires;
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}
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/**
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* timerqueue_add - Adds timer to timerqueue.
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*
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* @head: head of timerqueue
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* @node: timer node to be added
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*
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* Adds the timer node to the timerqueue, sorted by the node's expires
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* value. Returns true if the newly added timer is the first expiring timer in
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* the queue.
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*/
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bool timerqueue_add(struct timerqueue_head *head, struct timerqueue_node *node)
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{
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/* Make sure we don't add nodes that are already added */
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WARN_ON_ONCE(!RB_EMPTY_NODE(&node->node));
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return rb_add_cached(&node->node, &head->rb_root, __timerqueue_less);
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}
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EXPORT_SYMBOL_GPL(timerqueue_add);
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/**
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* timerqueue_del - Removes a timer from the timerqueue.
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*
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* @head: head of timerqueue
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* @node: timer node to be removed
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*
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* Removes the timer node from the timerqueue. Returns true if the queue is
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* not empty after the remove.
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*/
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bool timerqueue_del(struct timerqueue_head *head, struct timerqueue_node *node)
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{
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WARN_ON_ONCE(RB_EMPTY_NODE(&node->node));
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rb_erase_cached(&node->node, &head->rb_root);
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RB_CLEAR_NODE(&node->node);
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return !RB_EMPTY_ROOT(&head->rb_root.rb_root);
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}
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EXPORT_SYMBOL_GPL(timerqueue_del);
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/**
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* timerqueue_iterate_next - Returns the timer after the provided timer
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*
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* @node: Pointer to a timer.
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*
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* Provides the timer that is after the given node. This is used, when
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* necessary, to iterate through the list of timers in a timer list
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* without modifying the list.
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*/
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struct timerqueue_node *timerqueue_iterate_next(struct timerqueue_node *node)
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{
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struct rb_node *next;
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if (!node)
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return NULL;
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next = rb_next(&node->node);
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if (!next)
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return NULL;
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return container_of(next, struct timerqueue_node, node);
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}
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EXPORT_SYMBOL_GPL(timerqueue_iterate_next);
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