Quelle timerqueue.c Sprache: C

// 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>

#define __node_2_tq(_n) \
rb_entry((_n), struct timerqueue_node, node)

static inline bool __timerqueue_less(struct rb_node *a, const struct rb_node *b)
{
return __node_2_tq(a)->expires < __node_2_tq(b)->expires;
}

/**
* 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)
{
/* Make sure we don't add nodes that are already added */
WARN_ON_ONCE(!RB_EMPTY_NODE(&node->node));

return rb_add_cached(&node->node, &head->rb_root, __timerqueue_less);
}
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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