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/bug.h> 26 #include <linux/timerqueue.h> 27 #include <linux/rbtree.h> 28 #include <linux/export.h> 29 30 /** 31 * timerqueue_add - Adds timer to timerqueue. 32 * 33 * @head: head of timerqueue 34 * @node: timer node to be added 35 * 36 * Adds the timer node to the timerqueue, sorted by the 37 * node's expires value. 38 */ 39 bool timerqueue_add(struct timerqueue_head *head, struct timerqueue_node *node) 40 { 41 struct rb_node **p = &head->head.rb_node; 42 struct rb_node *parent = NULL; 43 struct timerqueue_node *ptr; 44 45 /* Make sure we don't add nodes that are already added */ 46 WARN_ON_ONCE(!RB_EMPTY_NODE(&node->node)); 47 48 while (*p) { 49 parent = *p; 50 ptr = rb_entry(parent, struct timerqueue_node, node); 51 if (node->expires.tv64 < ptr->expires.tv64) 52 p = &(*p)->rb_left; 53 else 54 p = &(*p)->rb_right; 55 } 56 rb_link_node(&node->node, parent, p); 57 rb_insert_color(&node->node, &head->head); 58 59 if (!head->next || node->expires.tv64 < head->next->expires.tv64) { 60 head->next = node; 61 return true; 62 } 63 return false; 64 } 65 EXPORT_SYMBOL_GPL(timerqueue_add); 66 67 /** 68 * timerqueue_del - Removes a timer from the timerqueue. 69 * 70 * @head: head of timerqueue 71 * @node: timer node to be removed 72 * 73 * Removes the timer node from the timerqueue. 74 */ 75 bool timerqueue_del(struct timerqueue_head *head, struct timerqueue_node *node) 76 { 77 WARN_ON_ONCE(RB_EMPTY_NODE(&node->node)); 78 79 /* update next pointer */ 80 if (head->next == node) { 81 struct rb_node *rbn = rb_next(&node->node); 82 83 head->next = rbn ? 84 rb_entry(rbn, struct timerqueue_node, node) : NULL; 85 } 86 rb_erase(&node->node, &head->head); 87 RB_CLEAR_NODE(&node->node); 88 return head->next != NULL; 89 } 90 EXPORT_SYMBOL_GPL(timerqueue_del); 91 92 /** 93 * timerqueue_iterate_next - Returns the timer after the provided timer 94 * 95 * @node: Pointer to a timer. 96 * 97 * Provides the timer that is after the given node. This is used, when 98 * necessary, to iterate through the list of timers in a timer list 99 * without modifying the list. 100 */ 101 struct timerqueue_node *timerqueue_iterate_next(struct timerqueue_node *node) 102 { 103 struct rb_node *next; 104 105 if (!node) 106 return NULL; 107 next = rb_next(&node->node); 108 if (!next) 109 return NULL; 110 return container_of(next, struct timerqueue_node, node); 111 } 112 EXPORT_SYMBOL_GPL(timerqueue_iterate_next); 113