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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 | /** |
138 | * plist_requeue - Requeue @node at end of same-prio entries. |
139 | * |
140 | * This is essentially an optimized plist_del() followed by |
141 | * plist_add(). It moves an entry already in the plist to |
142 | * after any other same-priority entries. |
143 | * |
144 | * @node: &struct plist_node pointer - entry to be moved |
145 | * @head: &struct plist_head pointer - list head |
146 | */ |
147 | void plist_requeue(struct plist_node *node, struct plist_head *head) |
148 | { |
149 | struct plist_node *iter; |
150 | struct list_head *node_next = &head->node_list; |
151 | |
152 | plist_check_head(head); |
153 | BUG_ON(plist_head_empty(head)); |
154 | BUG_ON(plist_node_empty(node)); |
155 | |
156 | if (node == plist_last(head)) |
157 | return; |
158 | |
159 | iter = plist_next(node); |
160 | |
161 | if (node->prio != iter->prio) |
162 | return; |
163 | |
164 | plist_del(node, head); |
165 | |
166 | plist_for_each_continue(iter, head) { |
167 | if (node->prio != iter->prio) { |
168 | node_next = &iter->node_list; |
169 | break; |
170 | } |
171 | } |
172 | list_add_tail(&node->node_list, node_next); |
173 | |
174 | plist_check_head(head); |
175 | } |
176 | |
177 | #ifdef CONFIG_DEBUG_PI_LIST |
178 | #include <linux/sched.h> |
179 | #include <linux/module.h> |
180 | #include <linux/init.h> |
181 | |
182 | static struct plist_node __initdata test_node[241]; |
183 | |
184 | static void __init plist_test_check(int nr_expect) |
185 | { |
186 | struct plist_node *first, *prio_pos, *node_pos; |
187 | |
188 | if (plist_head_empty(&test_head)) { |
189 | BUG_ON(nr_expect != 0); |
190 | return; |
191 | } |
192 | |
193 | prio_pos = first = plist_first(&test_head); |
194 | plist_for_each(node_pos, &test_head) { |
195 | if (nr_expect-- < 0) |
196 | break; |
197 | if (node_pos == first) |
198 | continue; |
199 | if (node_pos->prio == prio_pos->prio) { |
200 | BUG_ON(!list_empty(&node_pos->prio_list)); |
201 | continue; |
202 | } |
203 | |
204 | BUG_ON(prio_pos->prio > node_pos->prio); |
205 | BUG_ON(prio_pos->prio_list.next != &node_pos->prio_list); |
206 | prio_pos = node_pos; |
207 | } |
208 | |
209 | BUG_ON(nr_expect != 0); |
210 | BUG_ON(prio_pos->prio_list.next != &first->prio_list); |
211 | } |
212 | |
213 | static void __init plist_test_requeue(struct plist_node *node) |
214 | { |
215 | plist_requeue(node, &test_head); |
216 | |
217 | if (node != plist_last(&test_head)) |
218 | BUG_ON(node->prio == plist_next(node)->prio); |
219 | } |
220 | |
221 | static int __init plist_test(void) |
222 | { |
223 | int nr_expect = 0, i, loop; |
224 | unsigned int r = local_clock(); |
225 | |
226 | printk(KERN_DEBUG "start plist test\n"); |
227 | plist_head_init(&test_head); |
228 | for (i = 0; i < ARRAY_SIZE(test_node); i++) |
229 | plist_node_init(test_node + i, 0); |
230 | |
231 | for (loop = 0; loop < 1000; loop++) { |
232 | r = r * 193939 % 47629; |
233 | i = r % ARRAY_SIZE(test_node); |
234 | if (plist_node_empty(test_node + i)) { |
235 | r = r * 193939 % 47629; |
236 | test_node[i].prio = r % 99; |
237 | plist_add(test_node + i, &test_head); |
238 | nr_expect++; |
239 | } else { |
240 | plist_del(test_node + i, &test_head); |
241 | nr_expect--; |
242 | } |
243 | plist_test_check(nr_expect); |
244 | if (!plist_node_empty(test_node + i)) { |
245 | plist_test_requeue(test_node + i); |
246 | plist_test_check(nr_expect); |
247 | } |
248 | } |
249 | |
250 | for (i = 0; i < ARRAY_SIZE(test_node); i++) { |
251 | if (plist_node_empty(test_node + i)) |
252 | continue; |
253 | plist_del(test_node + i, &test_head); |
254 | nr_expect--; |
255 | plist_test_check(nr_expect); |
256 | } |
257 | |
258 | printk(KERN_DEBUG "end plist test\n"); |
259 | return 0; |
260 | } |
261 | |
262 | module_init(plist_test); |
263 | |
264 | #endif |
265 |
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