| 1 | |
| 2 | |
| 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 | |
| 18 | * timerqueue_add - Adds timer to timerqueue.
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| 19 | *
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| 20 | * @head: head of timerqueue
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| 21 | * @node: timer node to be added
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| 22 | *
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| 23 | * Adds the timer node to the timerqueue, sorted by the node's expires
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| 24 | * value. Returns true if the newly added timer is the first expiring timer in
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| 25 | * the queue.
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| 26 |
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| 27 | bool timerqueue_add(struct timerqueue_head *head, struct timerqueue_node *node)
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| 28 | {
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| 29 | struct rb_node **p = &head->head.rb_node;
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| 30 | struct rb_node *parent = NULL;
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| 31 | struct timerqueue_node *ptr;
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| 32 |
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| 33 |
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| 34 | WARN_ON_ONCE(!RB_EMPTY_NODE(&node->node));
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| 35 |
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| 36 | while (*p) {
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| 37 | parent = *p;
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| 38 | ptr = rb_entry(parent, struct timerqueue_node, node);
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| 39 | if (node->expires < ptr->expires)
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| 40 | p = &(*p)->rb_left;
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| 41 | else
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| 42 | p = &(*p)->rb_right;
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| 43 | }
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| 44 | rb_link_node(&node->node, parent, p);
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| 45 | rb_insert_color(&node->node, &head->head);
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| 46 |
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| 47 | if (!head->next || node->expires < head->next->expires) {
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| 48 | head->next = node;
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| 49 | return true;
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| 50 | }
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| 51 | return false;
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| 52 | }
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| 53 | EXPORT_SYMBOL_GPL(timerqueue_add);
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| 54 |
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| 55 | |
| 56 | * timerqueue_del - Removes a timer from the timerqueue.
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| 57 | *
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| 58 | * @head: head of timerqueue
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| 59 | * @node: timer node to be removed
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| 60 | *
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| 61 | * Removes the timer node from the timerqueue. Returns true if the queue is
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| 62 | * not empty after the remove.
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| 63 |
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| 64 | bool timerqueue_del(struct timerqueue_head *head, struct timerqueue_node *node)
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| 65 | {
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| 66 | WARN_ON_ONCE(RB_EMPTY_NODE(&node->node));
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| 67 |
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| 68 |
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| 69 | if (head->next == node) {
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| 70 | struct rb_node *rbn = rb_next(&node->node);
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| 71 |
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| 72 | head->next = rb_entry_safe(rbn, struct timerqueue_node, node);
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| 73 | }
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| 74 | rb_erase(&node->node, &head->head);
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| 75 | RB_CLEAR_NODE(&node->node);
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| 76 | return head->next != NULL;
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| 77 | }
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| 78 | EXPORT_SYMBOL_GPL(timerqueue_del);
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| 79 |
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| 80 | |
| 81 | * timerqueue_iterate_next - Returns the timer after the provided timer
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| 82 | *
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| 83 | * @node: Pointer to a timer.
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| 84 | *
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| 85 | * Provides the timer that is after the given node. This is used, when
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| 86 | * necessary, to iterate through the list of timers in a timer list
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| 87 | * without modifying the list.
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| 88 |
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| 89 | struct timerqueue_node *timerqueue_iterate_next(struct timerqueue_node *node)
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| 90 | {
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| 91 | struct rb_node *next;
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| 92 |
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| 93 | if (!node)
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| 94 | return NULL;
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| 95 | next = rb_next(&node->node);
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| 96 | if (!next)
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| 97 | return NULL;
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| 98 | return container_of(next, struct timerqueue_node, node);
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| 99 | }
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| 100 | EXPORT_SYMBOL_GPL(timerqueue_iterate_next);
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