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The hrtimer subsystem wants to peak ahead to the next and previous timer to evaluated whether a to be rearmed timer can stay at the same position in the RB tree with the new expiry time. The linked RB tree provides the infrastructure for this as it maintains links to the previous and next nodes for each entry in the tree. Provide timerqueue wrappers around that. Signed-off-by: Thomas Gleixner <tglx@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://patch.msgid.link/20260224163431.734827095@kernel.org
99 lines
2.8 KiB
C
99 lines
2.8 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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#define __node_2_tq_linked(_n) \
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container_of(rb_entry((_n), struct rb_node_linked, node), struct timerqueue_linked_node, node)
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static __always_inline bool __tq_linked_less(struct rb_node *a, const struct rb_node *b)
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{
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return __node_2_tq_linked(a)->expires < __node_2_tq_linked(b)->expires;
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}
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bool timerqueue_linked_add(struct timerqueue_linked_head *head, struct timerqueue_linked_node *node)
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{
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return rb_add_linked(&node->node, &head->rb_root, __tq_linked_less);
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}
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EXPORT_SYMBOL_GPL(timerqueue_linked_add);
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