| 1 | |
| 2 | |
| 3 | * Generic Timer-queue
|
| 4 | *
|
| 5 | * Manages a simple queue of timers, ordered by expiration time.
|
| 6 | * Uses rbtrees for quick list adds and expiration.
|
| 7 | *
|
| 8 | * NOTE: All of the following functions need to be serialized
|
| 9 | * to avoid races. No locking is done by this library code.
|
| 10 |
|
| 11 |
|
| 12 | #include <linux/bug.h>
|
| 13 | #include <linux/timerqueue.h>
|
| 14 | #include <linux/rbtree.h>
|
| 15 | #include <linux/export.h>
|
| 16 |
|
| 17 | |
| 18 | * timerqueue_add - Adds timer to timerqueue.
|
| 19 | *
|
| 20 | * @head: head of timerqueue
|
| 21 | * @node: timer node to be added
|
| 22 | *
|
| 23 | * Adds the timer node to the timerqueue, sorted by the node's expires
|
| 24 | * value. Returns true if the newly added timer is the first expiring timer in
|
| 25 | * the queue.
|
| 26 |
|
| 27 | bool timerqueue_add(struct timerqueue_head *head, struct timerqueue_node *node)
|
| 28 | {
|
| 29 | struct rb_node **p = &head->rb_root.rb_root.rb_node;
|
| 30 | struct rb_node *parent = NULL;
|
| 31 | struct timerqueue_node *ptr;
|
| 32 | bool leftmost = true;
|
| 33 |
|
| 34 |
|
| 35 | WARN_ON_ONCE(!RB_EMPTY_NODE(&node->node));
|
| 36 |
|
| 37 | while (*p) {
|
| 38 | parent = *p;
|
| 39 | ptr = rb_entry(parent, struct timerqueue_node, node);
|
| 40 | if (node->expires < ptr->expires) {
|
| 41 | p = &(*p)->rb_left;
|
| 42 | } else {
|
| 43 | p = &(*p)->rb_right;
|
| 44 | leftmost = false;
|
| 45 | }
|
| 46 | }
|
| 47 | rb_link_node(&node->node, parent, p);
|
| 48 | rb_insert_color_cached(&node->node, &head->rb_root, leftmost);
|
| 49 |
|
| 50 | return leftmost;
|
| 51 | }
|
| 52 | EXPORT_SYMBOL_GPL(timerqueue_add);
|
| 53 |
|
| 54 | |
| 55 | * timerqueue_del - Removes a timer from the timerqueue.
|
| 56 | *
|
| 57 | * @head: head of timerqueue
|
| 58 | * @node: timer node to be removed
|
| 59 | *
|
| 60 | * Removes the timer node from the timerqueue. Returns true if the queue is
|
| 61 | * not empty after the remove.
|
| 62 |
|
| 63 | bool timerqueue_del(struct timerqueue_head *head, struct timerqueue_node *node)
|
| 64 | {
|
| 65 | WARN_ON_ONCE(RB_EMPTY_NODE(&node->node));
|
| 66 |
|
| 67 | rb_erase_cached(&node->node, &head->rb_root);
|
| 68 | RB_CLEAR_NODE(&node->node);
|
| 69 |
|
| 70 | return !RB_EMPTY_ROOT(&head->rb_root.rb_root);
|
| 71 | }
|
| 72 | EXPORT_SYMBOL_GPL(timerqueue_del);
|
| 73 |
|
| 74 | |
| 75 | * timerqueue_iterate_next - Returns the timer after the provided timer
|
| 76 | *
|
| 77 | * @node: Pointer to a timer.
|
| 78 | *
|
| 79 | * Provides the timer that is after the given node. This is used, when
|
| 80 | * necessary, to iterate through the list of timers in a timer list
|
| 81 | * without modifying the list.
|
| 82 |
|
| 83 | struct timerqueue_node *timerqueue_iterate_next(struct timerqueue_node *node)
|
| 84 | {
|
| 85 | struct rb_node *next;
|
| 86 |
|
| 87 | if (!node)
|
| 88 | return NULL;
|
| 89 | next = rb_next(&node->node);
|
| 90 | if (!next)
|
| 91 | return NULL;
|
| 92 | return container_of(next, struct timerqueue_node, node);
|
| 93 | }
|
| 94 | EXPORT_SYMBOL_GPL(timerqueue_iterate_next);
|