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Ingo Molnar77ba89c2006-06-27 02:54:51 -07001/*
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
Paul Gortmaker50af5ea2012-01-20 18:35:53 -050026#include <linux/bug.h>
Ingo Molnar77ba89c2006-06-27 02:54:51 -070027#include <linux/plist.h>
28#include <linux/spinlock.h>
29
30#ifdef CONFIG_DEBUG_PI_LIST
31
Lai Jiangshan6d55da52010-12-21 17:55:18 +080032static struct plist_head test_head;
33
Ingo Molnar77ba89c2006-06-27 02:54:51 -070034static void plist_check_prev_next(struct list_head *t, struct list_head *p,
35 struct list_head *n)
36{
Arjan van de Ven5cd2b452008-07-25 19:45:39 -070037 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);
Ingo Molnar77ba89c2006-06-27 02:54:51 -070044}
45
46static 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
58static void plist_check_head(struct plist_head *head)
59{
Lai Jiangshanbf6a9b82010-12-21 17:55:14 +080060 if (!plist_head_empty(head))
61 plist_check_list(&plist_first(head)->prio_list);
Ingo Molnar77ba89c2006-06-27 02:54:51 -070062 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 */
75void plist_add(struct plist_node *node, struct plist_head *head)
76{
Lai Jiangshanbf6a9b82010-12-21 17:55:14 +080077 struct plist_node *first, *iter, *prev = NULL;
78 struct list_head *node_next = &head->node_list;
Ingo Molnar77ba89c2006-06-27 02:54:51 -070079
80 plist_check_head(head);
81 WARN_ON(!plist_node_empty(node));
Lai Jiangshanbf6a9b82010-12-21 17:55:14 +080082 WARN_ON(!list_empty(&node->prio_list));
Ingo Molnar77ba89c2006-06-27 02:54:51 -070083
Lai Jiangshanbf6a9b82010-12-21 17:55:14 +080084 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;
Ingo Molnar77ba89c2006-06-27 02:54:51 -070093 }
Ingo Molnar77ba89c2006-06-27 02:54:51 -070094
Lai Jiangshanbf6a9b82010-12-21 17:55:14 +080095 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);
102ins_node:
103 list_add_tail(&node->node_list, node_next);
Ingo Molnar77ba89c2006-06-27 02:54:51 -0700104
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 */
114void plist_del(struct plist_node *node, struct plist_head *head)
115{
116 plist_check_head(head);
117
Lai Jiangshanbf6a9b82010-12-21 17:55:14 +0800118 if (!list_empty(&node->prio_list)) {
119 if (node->node_list.next != &head->node_list) {
120 struct plist_node *next;
Ingo Molnar77ba89c2006-06-27 02:54:51 -0700121
Lai Jiangshanbf6a9b82010-12-21 17:55:14 +0800122 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);
Ingo Molnar77ba89c2006-06-27 02:54:51 -0700130 }
131
Lai Jiangshanbf6a9b82010-12-21 17:55:14 +0800132 list_del_init(&node->node_list);
Ingo Molnar77ba89c2006-06-27 02:54:51 -0700133
134 plist_check_head(head);
135}
Lai Jiangshan6d55da52010-12-21 17:55:18 +0800136
137#ifdef CONFIG_DEBUG_PI_LIST
138#include <linux/sched.h>
139#include <linux/module.h>
140#include <linux/init.h>
141
142static struct plist_node __initdata test_node[241];
143
144static 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
173static 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");
Dima Zavin732375c2011-07-07 17:27:59 -0700179 plist_head_init(&test_head);
Lai Jiangshan6d55da52010-12-21 17:55:18 +0800180 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
210module_init(plist_test);
211
212#endif