114 lines
3.3 KiB
C
114 lines
3.3 KiB
C
/*
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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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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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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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/**
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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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struct rb_node **p = &head->head.rb_node;
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struct rb_node *parent = NULL;
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struct timerqueue_node *ptr;
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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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while (*p) {
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parent = *p;
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ptr = rb_entry(parent, struct timerqueue_node, node);
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if (node->expires < ptr->expires)
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p = &(*p)->rb_left;
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else
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p = &(*p)->rb_right;
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}
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rb_link_node(&node->node, parent, p);
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rb_insert_color(&node->node, &head->head);
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if (!head->next || node->expires < head->next->expires) {
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head->next = node;
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return true;
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}
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return false;
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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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/* update next pointer */
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if (head->next == node) {
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struct rb_node *rbn = rb_next(&node->node);
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head->next = rb_entry_safe(rbn, struct timerqueue_node, node);
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}
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rb_erase(&node->node, &head->head);
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RB_CLEAR_NODE(&node->node);
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return head->next != NULL;
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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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