Line data    Source code

       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     1131789 : void timerqueue_add(struct timerqueue_head *head, struct timerqueue_node *node)
      40             : {
      41     1131789 :         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     6755435 :         while (*p) {
      49             :                 parent = *p;
      50             :                 ptr = rb_entry(parent, struct timerqueue_node, node);
      51     4491857 :                 if (node->expires.tv64 < ptr->expires.tv64)
      52     3634807 :                         p = &(*p)->rb_left;
      53             :                 else
      54      857050 :                         p = &(*p)->rb_right;
      55             :         }
      56     1131789 :         rb_link_node(&node->node, parent, p);
      57     1131789 :         rb_insert_color(&node->node, &head->head);
      58             : 
      59     1131789 :         if (!head->next || node->expires.tv64 < head->next->expires.tv64)
      60      291741 :                 head->next = node;
      61     1131789 : }
      62             : EXPORT_SYMBOL_GPL(timerqueue_add);
      63             : 
      64             : /**
      65             :  * timerqueue_del - Removes a timer from the timerqueue.
      66             :  *
      67             :  * @head: head of timerqueue
      68             :  * @node: timer node to be removed
      69             :  *
      70             :  * Removes the timer node from the timerqueue.
      71             :  */
      72     1131776 : void timerqueue_del(struct timerqueue_head *head, struct timerqueue_node *node)
      73             : {
      74             :         WARN_ON_ONCE(RB_EMPTY_NODE(&node->node));
      75             : 
      76             :         /* update next pointer */
      77     1131776 :         if (head->next == node) {
      78      309630 :                 struct rb_node *rbn = rb_next(&node->node);
      79             : 
      80      309630 :                 head->next = rbn ?
      81      309630 :                         rb_entry(rbn, struct timerqueue_node, node) : NULL;
      82             :         }
      83     1131776 :         rb_erase(&node->node, &head->head);
      84     1131776 :         RB_CLEAR_NODE(&node->node);
      85     1131776 : }
      86             : EXPORT_SYMBOL_GPL(timerqueue_del);
      87             : 
      88             : /**
      89             :  * timerqueue_iterate_next - Returns the timer after the provided timer
      90             :  *
      91             :  * @node: Pointer to a timer.
      92             :  *
      93             :  * Provides the timer that is after the given node. This is used, when
      94             :  * necessary, to iterate through the list of timers in a timer list
      95             :  * without modifying the list.
      96             :  */
      97           0 : struct timerqueue_node *timerqueue_iterate_next(struct timerqueue_node *node)
      98             : {
      99             :         struct rb_node *next;
     100             : 
     101           0 :         if (!node)
     102             :                 return NULL;
     103           0 :         next = rb_next(&node->node);
     104           0 :         if (!next)
     105             :                 return NULL;
     106           0 :         return container_of(next, struct timerqueue_node, node);
     107             : }
     108             : EXPORT_SYMBOL_GPL(timerqueue_iterate_next);