| 1 | |
| 2 | * Generic Timer-queue
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| 3 | *
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| 4 | * Manages a simple queue of timers, ordered by expiration time.
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| 5 | * Uses rbtrees for quick list adds and expiration.
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| 6 | *
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| 7 | * NOTE: All of the following functions need to be serialized
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| 8 | * to avoid races. No locking is done by this library code.
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| 9 | *
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| 10 | * This program is free software; you can redistribute it and/or modify
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| 11 | * it under the terms of the GNU General Public License as published by
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| 12 | * the Free Software Foundation; either version 2 of the License, or
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| 13 | * (at your option) any later version.
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| 14 | *
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| 15 | * This program is distributed in the hope that it will be useful,
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| 16 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 17 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 18 | * GNU General Public License for more details.
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| 19 | *
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| 20 | * You should have received a copy of the GNU General Public License
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| 21 | * along with this program; if not, write to the Free Software
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| 22 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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| 23 |
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| 24 |
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| 25 | #include <linux/timerqueue.h>
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| 26 | #include <linux/rbtree.h>
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| 27 | #include <linux/module.h>
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| 28 |
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| 29 | |
| 30 | * timerqueue_add - Adds timer to timerqueue.
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| 31 | *
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| 32 | * @head: head of timerqueue
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| 33 | * @node: timer node to be added
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| 34 | *
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| 35 | * Adds the timer node to the timerqueue, sorted by the
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| 36 | * node's expires value.
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| 37 |
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| 38 | void timerqueue_add(struct timerqueue_head *head, struct timerqueue_node *node)
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| 39 | {
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| 40 | struct rb_node **p = &head->head.rb_node;
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| 41 | struct rb_node *parent = NULL;
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| 42 | struct timerqueue_node *ptr;
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| 43 |
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| 44 |
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| 45 | WARN_ON_ONCE(!RB_EMPTY_NODE(&node->node));
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| 46 |
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| 47 | while (*p) {
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| 48 | parent = *p;
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| 49 | ptr = rb_entry(parent, struct timerqueue_node, node);
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| 50 | if (node->expires.tv64 < ptr->expires.tv64)
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| 51 | p = &(*p)->rb_left;
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| 52 | else
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| 53 | p = &(*p)->rb_right;
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| 54 | }
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| 55 | rb_link_node(&node->node, parent, p);
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| 56 | rb_insert_color(&node->node, &head->head);
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| 57 |
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| 58 | if (!head->next || node->expires.tv64 < head->next->expires.tv64)
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| 59 | head->next = node;
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| 60 | }
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| 61 | EXPORT_SYMBOL_GPL(timerqueue_add);
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| 62 |
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| 63 | |
| 64 | * timerqueue_del - Removes a timer from the timerqueue.
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| 65 | *
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| 66 | * @head: head of timerqueue
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| 67 | * @node: timer node to be removed
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| 68 | *
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| 69 | * Removes the timer node from the timerqueue.
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| 70 |
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| 71 | void timerqueue_del(struct timerqueue_head *head, struct timerqueue_node *node)
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| 72 | {
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| 73 | WARN_ON_ONCE(RB_EMPTY_NODE(&node->node));
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| 74 |
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| 75 |
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| 76 | if (head->next == node) {
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| 77 | struct rb_node *rbn = rb_next(&node->node);
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| 78 |
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| 79 | head->next = rbn ?
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| 80 | rb_entry(rbn, struct timerqueue_node, node) : NULL;
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| 81 | }
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| 82 | rb_erase(&node->node, &head->head);
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| 83 | RB_CLEAR_NODE(&node->node);
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| 84 | }
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| 85 | EXPORT_SYMBOL_GPL(timerqueue_del);
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| 86 |
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| 87 | |
| 88 | * timerqueue_iterate_next - Returns the timer after the provided timer
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| 89 | *
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| 90 | * @node: Pointer to a timer.
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| 91 | *
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| 92 | * Provides the timer that is after the given node. This is used, when
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| 93 | * necessary, to iterate through the list of timers in a timer list
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| 94 | * without modifying the list.
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| 95 |
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| 96 | struct timerqueue_node *timerqueue_iterate_next(struct timerqueue_node *node)
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| 97 | {
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| 98 | struct rb_node *next;
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| 99 |
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| 100 | if (!node)
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| 101 | return NULL;
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| 102 | next = rb_next(&node->node);
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| 103 | if (!next)
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| 104 | return NULL;
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| 105 | return container_of(next, struct timerqueue_node, node);
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| 106 | }
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| 107 | EXPORT_SYMBOL_GPL(timerqueue_iterate_next);
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