FreeBSD/Linux Kernel Cross Reference
sys/lib/plist.c

     /*
      * lib/plist.c
      *
      * Descending-priority-sorted double-linked list
      *
      * (C) 2002-2003 Intel Corp
      * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>.
      *
      * 2001-2005 (c) MontaVista Software, Inc.
     * Daniel Walker <dwalker@mvista.com>
     *
     * (C) 2005 Thomas Gleixner <tglx@linutronix.de>
     *
     * Simplifications of the original code by
     * Oleg Nesterov <oleg@tv-sign.ru>
     *
     * Licensed under the FSF's GNU Public License v2 or later.
     *
     * Based on simple lists (include/linux/list.h).
     *
     * This file contains the add / del functions which are considered to
     * be too large to inline. See include/linux/plist.h for further
     * information.
     */
    
    #include <linux/bug.h>
    #include <linux/plist.h>
    #include <linux/spinlock.h>
    
    #ifdef CONFIG_DEBUG_PI_LIST
    
    static struct plist_head test_head;
    
    static void plist_check_prev_next(struct list_head *t, struct list_head *p,
                                      struct list_head *n)
    {
            WARN(n->prev != p || p->next != n,
                            "top: %p, n: %p, p: %p\n"
                            "prev: %p, n: %p, p: %p\n"
                            "next: %p, n: %p, p: %p\n",
                             t, t->next, t->prev,
                            p, p->next, p->prev,
                            n, n->next, n->prev);
    }
    
    static void plist_check_list(struct list_head *top)
    {
            struct list_head *prev = top, *next = top->next;
    
            plist_check_prev_next(top, prev, next);
            while (next != top) {
                    prev = next;
                    next = prev->next;
                    plist_check_prev_next(top, prev, next);
            }
    }
    
    static void plist_check_head(struct plist_head *head)
    {
            if (!plist_head_empty(head))
                    plist_check_list(&plist_first(head)->prio_list);
            plist_check_list(&head->node_list);
    }
    
    #else
    # define plist_check_head(h)    do { } while (0)
    #endif
    
    /**
     * plist_add - add @node to @head
     *
     * @node:       &struct plist_node pointer
     * @head:       &struct plist_head pointer
     */
    void plist_add(struct plist_node *node, struct plist_head *head)
    {
            struct plist_node *first, *iter, *prev = NULL;
            struct list_head *node_next = &head->node_list;
    
            plist_check_head(head);
            WARN_ON(!plist_node_empty(node));
            WARN_ON(!list_empty(&node->prio_list));
    
            if (plist_head_empty(head))
                    goto ins_node;
    
            first = iter = plist_first(head);
    
            do {
                    if (node->prio < iter->prio) {
                            node_next = &iter->node_list;
                            break;
                    }
    
                    prev = iter;
                    iter = list_entry(iter->prio_list.next,
                                    struct plist_node, prio_list);
            } while (iter != first);
    
           if (!prev || prev->prio != node->prio)
                   list_add_tail(&node->prio_list, &iter->prio_list);
   ins_node:
           list_add_tail(&node->node_list, node_next);
   
           plist_check_head(head);
   }
   
   /**
    * plist_del - Remove a @node from plist.
    *
    * @node:       &struct plist_node pointer - entry to be removed
    * @head:       &struct plist_head pointer - list head
    */
   void plist_del(struct plist_node *node, struct plist_head *head)
   {
           plist_check_head(head);
   
           if (!list_empty(&node->prio_list)) {
                   if (node->node_list.next != &head->node_list) {
                           struct plist_node *next;
   
                           next = list_entry(node->node_list.next,
                                           struct plist_node, node_list);
   
                           /* add the next plist_node into prio_list */
                           if (list_empty(&next->prio_list))
                                   list_add(&next->prio_list, &node->prio_list);
                   }
                   list_del_init(&node->prio_list);
           }
   
           list_del_init(&node->node_list);
   
           plist_check_head(head);
   }
   
   #ifdef CONFIG_DEBUG_PI_LIST
   #include <linux/sched.h>
   #include <linux/module.h>
   #include <linux/init.h>
   
   static struct plist_node __initdata test_node[241];
   
   static void __init plist_test_check(int nr_expect)
   {
           struct plist_node *first, *prio_pos, *node_pos;
   
           if (plist_head_empty(&test_head)) {
                   BUG_ON(nr_expect != 0);
                   return;
           }
   
           prio_pos = first = plist_first(&test_head);
           plist_for_each(node_pos, &test_head) {
                   if (nr_expect-- < 0)
                           break;
                   if (node_pos == first)
                           continue;
                   if (node_pos->prio == prio_pos->prio) {
                           BUG_ON(!list_empty(&node_pos->prio_list));
                           continue;
                   }
   
                   BUG_ON(prio_pos->prio > node_pos->prio);
                   BUG_ON(prio_pos->prio_list.next != &node_pos->prio_list);
                   prio_pos = node_pos;
           }
   
           BUG_ON(nr_expect != 0);
           BUG_ON(prio_pos->prio_list.next != &first->prio_list);
   }
   
   static int  __init plist_test(void)
   {
           int nr_expect = 0, i, loop;
           unsigned int r = local_clock();
   
           pr_debug("start plist test\n");
           plist_head_init(&test_head);
           for (i = 0; i < ARRAY_SIZE(test_node); i++)
                   plist_node_init(test_node + i, 0);
   
           for (loop = 0; loop < 1000; loop++) {
                   r = r * 193939 % 47629;
                   i = r % ARRAY_SIZE(test_node);
                   if (plist_node_empty(test_node + i)) {
                           r = r * 193939 % 47629;
                           test_node[i].prio = r % 99;
                           plist_add(test_node + i, &test_head);
                           nr_expect++;
                   } else {
                           plist_del(test_node + i, &test_head);
                           nr_expect--;
                   }
                   plist_test_check(nr_expect);
           }
   
           for (i = 0; i < ARRAY_SIZE(test_node); i++) {
                   if (plist_node_empty(test_node + i))
                           continue;
                   plist_del(test_node + i, &test_head);
                   nr_expect--;
                   plist_test_check(nr_expect);
           }
   
           pr_debug("end plist test\n");
           return 0;
   }
   
   module_init(plist_test);
   
   #endif

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