Linux/lib/plist.c

  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/bug.h>
 27 #include <linux/plist.h>
 28 #include <linux/spinlock.h>
 29 
 30 #ifdef CONFIG_DEBUG_PI_LIST
 31 
 32 static struct plist_head test_head;
 33 
 34 static void plist_check_prev_next(struct list_head *t, struct list_head *p,
 35                                   struct list_head *n)
 36 {
 37         WARN(n->prev != p || p->next != n,
 38                         "top: %p, n: %p, p: %p\n"
 39                         "prev: %p, n: %p, p: %p\n"
 40                         "next: %p, n: %p, p: %p\n",
 41                          t, t->next, t->prev,
 42                         p, p->next, p->prev,
 43                         n, n->next, n->prev);
 44 }
 45 
 46 static void plist_check_list(struct list_head *top)
 47 {
 48         struct list_head *prev = top, *next = top->next;
 49 
 50         plist_check_prev_next(top, prev, next);
 51         while (next != top) {
 52                 prev = next;
 53                 next = prev->next;
 54                 plist_check_prev_next(top, prev, next);
 55         }
 56 }
 57 
 58 static void plist_check_head(struct plist_head *head)
 59 {
 60         if (!plist_head_empty(head))
 61                 plist_check_list(&plist_first(head)->prio_list);
 62         plist_check_list(&head->node_list);
 63 }
 64 
 65 #else
 66 # define plist_check_head(h)    do { } while (0)
 67 #endif
 68 
 69 /**
 70  * plist_add - add @node to @head
 71  *
 72  * @node:       &struct plist_node pointer
 73  * @head:       &struct plist_head pointer
 74  */
 75 void plist_add(struct plist_node *node, struct plist_head *head)
 76 {
 77         struct plist_node *first, *iter, *prev = NULL;
 78         struct list_head *node_next = &head->node_list;
 79 
 80         plist_check_head(head);
 81         WARN_ON(!plist_node_empty(node));
 82         WARN_ON(!list_empty(&node->prio_list));
 83 
 84         if (plist_head_empty(head))
 85                 goto ins_node;
 86 
 87         first = iter = plist_first(head);
 88 
 89         do {
 90                 if (node->prio < iter->prio) {
 91                         node_next = &iter->node_list;
 92                         break;
 93                 }
 94 
 95                 prev = iter;
 96                 iter = list_entry(iter->prio_list.next,
 97                                 struct plist_node, prio_list);
 98         } while (iter != first);
 99 
100         if (!prev || prev->prio != node->prio)
101                 list_add_tail(&node->prio_list, &iter->prio_list);
102 ins_node:
103         list_add_tail(&node->node_list, node_next);
104 
105         plist_check_head(head);
106 }
107 
108 /**
109  * plist_del - Remove a @node from plist.
110  *
111  * @node:       &struct plist_node pointer - entry to be removed
112  * @head:       &struct plist_head pointer - list head
113  */
114 void plist_del(struct plist_node *node, struct plist_head *head)
115 {
116         plist_check_head(head);
117 
118         if (!list_empty(&node->prio_list)) {
119                 if (node->node_list.next != &head->node_list) {
120                         struct plist_node *next;
121 
122                         next = list_entry(node->node_list.next,
123                                         struct plist_node, node_list);
124 
125                         /* add the next plist_node into prio_list */
126                         if (list_empty(&next->prio_list))
127                                 list_add(&next->prio_list, &node->prio_list);
128                 }
129                 list_del_init(&node->prio_list);
130         }
131 
132         list_del_init(&node->node_list);
133 
134         plist_check_head(head);
135 }
136 
137 #ifdef CONFIG_DEBUG_PI_LIST
138 #include <linux/sched.h>
139 #include <linux/module.h>
140 #include <linux/init.h>
141 
142 static struct plist_node __initdata test_node[241];
143 
144 static void __init plist_test_check(int nr_expect)
145 {
146         struct plist_node *first, *prio_pos, *node_pos;
147 
148         if (plist_head_empty(&test_head)) {
149                 BUG_ON(nr_expect != 0);
150                 return;
151         }
152 
153         prio_pos = first = plist_first(&test_head);
154         plist_for_each(node_pos, &test_head) {
155                 if (nr_expect-- < 0)
156                         break;
157                 if (node_pos == first)
158                         continue;
159                 if (node_pos->prio == prio_pos->prio) {
160                         BUG_ON(!list_empty(&node_pos->prio_list));
161                         continue;
162                 }
163 
164                 BUG_ON(prio_pos->prio > node_pos->prio);
165                 BUG_ON(prio_pos->prio_list.next != &node_pos->prio_list);
166                 prio_pos = node_pos;
167         }
168 
169         BUG_ON(nr_expect != 0);
170         BUG_ON(prio_pos->prio_list.next != &first->prio_list);
171 }
172 
173 static int  __init plist_test(void)
174 {
175         int nr_expect = 0, i, loop;
176         unsigned int r = local_clock();
177 
178         printk(KERN_INFO "start plist test\n");
179         plist_head_init(&test_head);
180         for (i = 0; i < ARRAY_SIZE(test_node); i++)
181                 plist_node_init(test_node + i, 0);
182 
183         for (loop = 0; loop < 1000; loop++) {
184                 r = r * 193939 % 47629;
185                 i = r % ARRAY_SIZE(test_node);
186                 if (plist_node_empty(test_node + i)) {
187                         r = r * 193939 % 47629;
188                         test_node[i].prio = r % 99;
189                         plist_add(test_node + i, &test_head);
190                         nr_expect++;
191                 } else {
192                         plist_del(test_node + i, &test_head);
193                         nr_expect--;
194                 }
195                 plist_test_check(nr_expect);
196         }
197 
198         for (i = 0; i < ARRAY_SIZE(test_node); i++) {
199                 if (plist_node_empty(test_node + i))
200                         continue;
201                 plist_del(test_node + i, &test_head);
202                 nr_expect--;
203                 plist_test_check(nr_expect);
204         }
205 
206         printk(KERN_INFO "end plist test\n");
207         return 0;
208 }
209 
210 module_init(plist_test);
211 
212 #endif
213

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