linux/lib/plist.c
<<
>>
Prefs
   1/*
   2 * lib/plist.c
   3 *
   4 * Descending-priority-sorted double-linked list
   5 *
   6 * (C) 2002-2003 Intel Corp
   7 * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>.
   8 *
   9 * 2001-2005 (c) MontaVista Software, Inc.
  10 * Daniel Walker <dwalker@mvista.com>
  11 *
  12 * (C) 2005 Thomas Gleixner <tglx@linutronix.de>
  13 *
  14 * Simplifications of the original code by
  15 * Oleg Nesterov <oleg@tv-sign.ru>
  16 *
  17 * Licensed under the FSF's GNU Public License v2 or later.
  18 *
  19 * Based on simple lists (include/linux/list.h).
  20 *
  21 * This file contains the add / del functions which are considered to
  22 * be too large to inline. See include/linux/plist.h for further
  23 * information.
  24 */
  25
  26#include <linux/plist.h>
  27#include <linux/spinlock.h>
  28
  29#ifdef CONFIG_DEBUG_PI_LIST
  30
  31static struct plist_head test_head;
  32
  33static void plist_check_prev_next(struct list_head *t, struct list_head *p,
  34                                  struct list_head *n)
  35{
  36        WARN(n->prev != p || p->next != n,
  37                        "top: %p, n: %p, p: %p\n"
  38                        "prev: %p, n: %p, p: %p\n"
  39                        "next: %p, n: %p, p: %p\n",
  40                         t, t->next, t->prev,
  41                        p, p->next, p->prev,
  42                        n, n->next, n->prev);
  43}
  44
  45static void plist_check_list(struct list_head *top)
  46{
  47        struct list_head *prev = top, *next = top->next;
  48
  49        plist_check_prev_next(top, prev, next);
  50        while (next != top) {
  51                prev = next;
  52                next = prev->next;
  53                plist_check_prev_next(top, prev, next);
  54        }
  55}
  56
  57static void plist_check_head(struct plist_head *head)
  58{
  59        if (!plist_head_empty(head))
  60                plist_check_list(&plist_first(head)->prio_list);
  61        plist_check_list(&head->node_list);
  62}
  63
  64#else
  65# define plist_check_head(h)    do { } while (0)
  66#endif
  67
  68/**
  69 * plist_add - add @node to @head
  70 *
  71 * @node:       &struct plist_node pointer
  72 * @head:       &struct plist_head pointer
  73 */
  74void plist_add(struct plist_node *node, struct plist_head *head)
  75{
  76        struct plist_node *first, *iter, *prev = NULL;
  77        struct list_head *node_next = &head->node_list;
  78
  79        plist_check_head(head);
  80        WARN_ON(!plist_node_empty(node));
  81        WARN_ON(!list_empty(&node->prio_list));
  82
  83        if (plist_head_empty(head))
  84                goto ins_node;
  85
  86        first = iter = plist_first(head);
  87
  88        do {
  89                if (node->prio < iter->prio) {
  90                        node_next = &iter->node_list;
  91                        break;
  92                }
  93
  94                prev = iter;
  95                iter = list_entry(iter->prio_list.next,
  96                                struct plist_node, prio_list);
  97        } while (iter != first);
  98
  99        if (!prev || prev->prio != node->prio)
 100                list_add_tail(&node->prio_list, &iter->prio_list);
 101ins_node:
 102        list_add_tail(&node->node_list, node_next);
 103
 104        plist_check_head(head);
 105}
 106
 107/**
 108 * plist_del - Remove a @node from plist.
 109 *
 110 * @node:       &struct plist_node pointer - entry to be removed
 111 * @head:       &struct plist_head pointer - list head
 112 */
 113void plist_del(struct plist_node *node, struct plist_head *head)
 114{
 115        plist_check_head(head);
 116
 117        if (!list_empty(&node->prio_list)) {
 118                if (node->node_list.next != &head->node_list) {
 119                        struct plist_node *next;
 120
 121                        next = list_entry(node->node_list.next,
 122                                        struct plist_node, node_list);
 123
 124                        /* add the next plist_node into prio_list */
 125                        if (list_empty(&next->prio_list))
 126                                list_add(&next->prio_list, &node->prio_list);
 127                }
 128                list_del_init(&node->prio_list);
 129        }
 130
 131        list_del_init(&node->node_list);
 132
 133        plist_check_head(head);
 134}
 135
 136#ifdef CONFIG_DEBUG_PI_LIST
 137#include <linux/sched.h>
 138#include <linux/module.h>
 139#include <linux/init.h>
 140
 141static struct plist_node __initdata test_node[241];
 142
 143static void __init plist_test_check(int nr_expect)
 144{
 145        struct plist_node *first, *prio_pos, *node_pos;
 146
 147        if (plist_head_empty(&test_head)) {
 148                BUG_ON(nr_expect != 0);
 149                return;
 150        }
 151
 152        prio_pos = first = plist_first(&test_head);
 153        plist_for_each(node_pos, &test_head) {
 154                if (nr_expect-- < 0)
 155                        break;
 156                if (node_pos == first)
 157                        continue;
 158                if (node_pos->prio == prio_pos->prio) {
 159                        BUG_ON(!list_empty(&node_pos->prio_list));
 160                        continue;
 161                }
 162
 163                BUG_ON(prio_pos->prio > node_pos->prio);
 164                BUG_ON(prio_pos->prio_list.next != &node_pos->prio_list);
 165                prio_pos = node_pos;
 166        }
 167
 168        BUG_ON(nr_expect != 0);
 169        BUG_ON(prio_pos->prio_list.next != &first->prio_list);
 170}
 171
 172static int  __init plist_test(void)
 173{
 174        int nr_expect = 0, i, loop;
 175        unsigned int r = local_clock();
 176
 177        printk(KERN_INFO "start plist test\n");
 178        plist_head_init(&test_head);
 179        for (i = 0; i < ARRAY_SIZE(test_node); i++)
 180                plist_node_init(test_node + i, 0);
 181
 182        for (loop = 0; loop < 1000; loop++) {
 183                r = r * 193939 % 47629;
 184                i = r % ARRAY_SIZE(test_node);
 185                if (plist_node_empty(test_node + i)) {
 186                        r = r * 193939 % 47629;
 187                        test_node[i].prio = r % 99;
 188                        plist_add(test_node + i, &test_head);
 189                        nr_expect++;
 190                } else {
 191                        plist_del(test_node + i, &test_head);
 192                        nr_expect--;
 193                }
 194                plist_test_check(nr_expect);
 195        }
 196
 197        for (i = 0; i < ARRAY_SIZE(test_node); i++) {
 198                if (plist_node_empty(test_node + i))
 199                        continue;
 200                plist_del(test_node + i, &test_head);
 201                nr_expect--;
 202                plist_test_check(nr_expect);
 203        }
 204
 205        printk(KERN_INFO "end plist test\n");
 206        return 0;
 207}
 208
 209module_init(plist_test);
 210
 211#endif
 212
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.