87de5ac782
The timerlist infrastructure is a thin layer over the rbtree code that implements a simple list of timers sorted by an expires value, and a getnext function that provides a pointer to the earliest timer. This infrastructure allows drivers and other kernel infrastructure to easily implement timers without duplicating code. Signed-off-by: John Stultz <john.stultz@linaro.org> LKML Reference: <1290136329-18291-2-git-send-email-john.stultz@linaro.org> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> CC: Alessandro Zummo <a.zummo@towertech.it> CC: Thomas Gleixner <tglx@linutronix.de> CC: Richard Cochran <richardcochran@gmail.com>
119 lines
3.2 KiB
C
119 lines
3.2 KiB
C
/*
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* Generic Timer-list
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*
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* Manages a simple list 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 libary 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/timerlist.h>
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#include <linux/rbtree.h>
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/**
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* timerlist_add - Adds timer to timerlist.
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*
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* @head: head of timerlist
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* @node: timer node to be added
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*
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* Adds the timer node to the timerlist, sorted by the
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* node's expires value.
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*/
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void timerlist_add(struct timerlist_head *head, struct timerlist_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 timerlist_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 timerlist_node, node);
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if (node->expires.tv64 < ptr->expires.tv64)
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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.tv64 < head->next->expires.tv64)
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head->next = node;
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}
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/**
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* timerlist_del - Removes a timer from the timerlist.
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*
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* @head: head of timerlist
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* @node: timer node to be removed
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*
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* Removes the timer node from the timerlist.
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*/
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void timerlist_del(struct timerlist_head *head, struct timerlist_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 = rbn ?
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rb_entry(rbn, struct timerlist_node, node) : NULL;
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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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}
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/**
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* timerlist_getnext - Returns the timer with the earlies expiration time
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*
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* @head: head of timerlist
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*
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* Returns a pointer to the timer node that has the
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* earliest expiration time.
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*/
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struct timerlist_node *timerlist_getnext(struct timerlist_head *head)
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{
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return head->next;
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}
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/**
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* timerlist_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 timerlist_node *timerlist_iterate_next(struct timerlist_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 timerlist_node, node);
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}
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