| 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
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| 2 | /* |
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| 3 | * Generic Timer-queue |
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| 4 | * |
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| 5 | * Manages a simple queue of timers, ordered by expiration time. |
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| 6 | * Uses rbtrees for quick list adds and expiration. |
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| 7 | * |
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| 8 | * NOTE: All of the following functions need to be serialized |
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| 9 | * to avoid races. No locking is done by this library code. |
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| 10 | */ |
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| 11 | |
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| 12 | #include <linux/bug.h> |
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| 13 | #include <linux/timerqueue.h> |
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| 14 | #include <linux/rbtree.h> |
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| 15 | #include <linux/export.h> |
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| 16 | |
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| 17 | #define __node_2_tq(_n) \ |
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| 18 | rb_entry((_n), struct timerqueue_node, node) |
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| 19 | |
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| 20 | static inline bool __timerqueue_less(struct rb_node *a, const struct rb_node *b) |
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| 21 | { |
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| 22 | return __node_2_tq(a)->expires < __node_2_tq(b)->expires; |
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| 23 | } |
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| 24 | |
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| 25 | /** |
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| 26 | * timerqueue_add - Adds timer to timerqueue. |
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| 27 | * |
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| 28 | * @head: head of timerqueue |
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| 29 | * @node: timer node to be added |
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| 30 | * |
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| 31 | * Adds the timer node to the timerqueue, sorted by the node's expires |
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| 32 | * value. Returns true if the newly added timer is the first expiring timer in |
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| 33 | * the queue. |
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| 34 | */ |
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| 35 | bool timerqueue_add(struct timerqueue_head *head, struct timerqueue_node *node) |
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| 36 | { |
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| 37 | /* Make sure we don't add nodes that are already added */ |
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| 38 | WARN_ON_ONCE(!RB_EMPTY_NODE(&node->node)); |
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| 39 | |
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| 40 | return rb_add_cached(node: &node->node, tree: &head->rb_root, less: __timerqueue_less); |
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| 41 | } |
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| 42 | EXPORT_SYMBOL_GPL(timerqueue_add); |
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| 43 | |
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| 44 | /** |
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| 45 | * timerqueue_del - Removes a timer from the timerqueue. |
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| 46 | * |
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| 47 | * @head: head of timerqueue |
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| 48 | * @node: timer node to be removed |
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| 49 | * |
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| 50 | * Removes the timer node from the timerqueue. Returns true if the queue is |
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| 51 | * not empty after the remove. |
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| 52 | */ |
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| 53 | bool timerqueue_del(struct timerqueue_head *head, struct timerqueue_node *node) |
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| 54 | { |
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| 55 | WARN_ON_ONCE(RB_EMPTY_NODE(&node->node)); |
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| 56 | |
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| 57 | rb_erase_cached(node: &node->node, root: &head->rb_root); |
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| 58 | RB_CLEAR_NODE(&node->node); |
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| 59 | |
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| 60 | return !RB_EMPTY_ROOT(&head->rb_root.rb_root); |
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| 61 | } |
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| 62 | EXPORT_SYMBOL_GPL(timerqueue_del); |
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| 63 | |
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| 64 | /** |
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| 65 | * timerqueue_iterate_next - Returns the timer after the provided timer |
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| 66 | * |
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| 67 | * @node: Pointer to a timer. |
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| 68 | * |
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| 69 | * Provides the timer that is after the given node. This is used, when |
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| 70 | * necessary, to iterate through the list of timers in a timer list |
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| 71 | * without modifying the list. |
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| 72 | */ |
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| 73 | struct timerqueue_node *timerqueue_iterate_next(struct timerqueue_node *node) |
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| 74 | { |
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| 75 | struct rb_node *next; |
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| 76 | |
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| 77 | if (!node) |
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| 78 | return NULL; |
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| 79 | next = rb_next(&node->node); |
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| 80 | if (!next) |
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| 81 | return NULL; |
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| 82 | return container_of(next, struct timerqueue_node, node); |
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| 83 | } |
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| 84 | EXPORT_SYMBOL_GPL(timerqueue_iterate_next); |
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| 85 | |
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