1 /* 2 * Generic Timer-queue 3 * 4 * Manages a simple queue of timers, ordered by expiration time. 5 * Uses rbtrees for quick list adds and expiration. 6 * 7 * NOTE: All of the following functions need to be serialized 8 * to avoid races. No locking is done by this library code. 9 * 10 * This program is free software; you can redistribute it and/or modify 11 * it under the terms of the GNU General Public License as published by 12 * the Free Software Foundation; either version 2 of the License, or 13 * (at your option) any later version. 14 * 15 * This program is distributed in the hope that it will be useful, 16 * but WITHOUT ANY WARRANTY; without even the implied warranty of 17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 18 * GNU General Public License for more details. 19 * 20 * You should have received a copy of the GNU General Public License 21 * along with this program; if not, write to the Free Software 22 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 23 */ 24 25 #include <linux/timerqueue.h> 26 #include <linux/rbtree.h> 27 #include <linux/module.h> 28 29 /** 30 * timerqueue_add - Adds timer to timerqueue. 31 * 32 * @head: head of timerqueue 33 * @node: timer node to be added 34 * 35 * Adds the timer node to the timerqueue, sorted by the 36 * node's expires value. 37 */ 38 void timerqueue_add(struct timerqueue_head *head, struct timerqueue_node *node) 39 { 40 struct rb_node **p = &head->head.rb_node; 41 struct rb_node *parent = NULL; 42 struct timerqueue_node *ptr; 43 44 /* Make sure we don't add nodes that are already added */ 45 WARN_ON_ONCE(!RB_EMPTY_NODE(&node->node)); 46 47 while (*p) { 48 parent = *p; 49 ptr = rb_entry(parent, struct timerqueue_node, node); 50 if (node->expires.tv64 < ptr->expires.tv64) 51 p = &(*p)->rb_left; 52 else 53 p = &(*p)->rb_right; 54 } 55 rb_link_node(&node->node, parent, p); 56 rb_insert_color(&node->node, &head->head); 57 58 if (!head->next || node->expires.tv64 < head->next->expires.tv64) 59 head->next = node; 60 } 61 EXPORT_SYMBOL_GPL(timerqueue_add); 62 63 /** 64 * timerqueue_del - Removes a timer from the timerqueue. 65 * 66 * @head: head of timerqueue 67 * @node: timer node to be removed 68 * 69 * Removes the timer node from the timerqueue. 70 */ 71 void timerqueue_del(struct timerqueue_head *head, struct timerqueue_node *node) 72 { 73 WARN_ON_ONCE(RB_EMPTY_NODE(&node->node)); 74 75 /* update next pointer */ 76 if (head->next == node) { 77 struct rb_node *rbn = rb_next(&node->node); 78 79 head->next = rbn ? 80 rb_entry(rbn, struct timerqueue_node, node) : NULL; 81 } 82 rb_erase(&node->node, &head->head); 83 RB_CLEAR_NODE(&node->node); 84 } 85 EXPORT_SYMBOL_GPL(timerqueue_del); 86 87 /** 88 * timerqueue_iterate_next - Returns the timer after the provided timer 89 * 90 * @node: Pointer to a timer. 91 * 92 * Provides the timer that is after the given node. This is used, when 93 * necessary, to iterate through the list of timers in a timer list 94 * without modifying the list. 95 */ 96 struct timerqueue_node *timerqueue_iterate_next(struct timerqueue_node *node) 97 { 98 struct rb_node *next; 99 100 if (!node) 101 return NULL; 102 next = rb_next(&node->node); 103 if (!next) 104 return NULL; 105 return container_of(next, struct timerqueue_node, node); 106 } 107 EXPORT_SYMBOL_GPL(timerqueue_iterate_next); 108