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 29 #ifdef CONFIG_DEBUG_PI_LIST 30 31 static struct plist_head test_head; 32 33 static 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 45 static 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 57 static 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 */ 74 void 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); 101 ins_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 */ 113 void 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 /** 137 * plist_requeue - Requeue @node at end of same-prio entries. 138 * 139 * This is essentially an optimized plist_del() followed by 140 * plist_add(). It moves an entry already in the plist to 141 * after any other same-priority entries. 142 * 143 * @node: &struct plist_node pointer - entry to be moved 144 * @head: &struct plist_head pointer - list head 145 */ 146 void plist_requeue(struct plist_node *node, struct plist_head *head) 147 { 148 struct plist_node *iter; 149 struct list_head *node_next = &head->node_list; 150 151 plist_check_head(head); 152 BUG_ON(plist_head_empty(head)); 153 BUG_ON(plist_node_empty(node)); 154 155 if (node == plist_last(head)) 156 return; 157 158 iter = plist_next(node); 159 160 if (node->prio != iter->prio) 161 return; 162 163 plist_del(node, head); 164 165 plist_for_each_continue(iter, head) { 166 if (node->prio != iter->prio) { 167 node_next = &iter->node_list; 168 break; 169 } 170 } 171 list_add_tail(&node->node_list, node_next); 172 173 plist_check_head(head); 174 } 175 176 #ifdef CONFIG_DEBUG_PI_LIST 177 #include <linux/sched.h> 178 #include <linux/module.h> 179 #include <linux/init.h> 180 181 static struct plist_node __initdata test_node[241]; 182 183 static void __init plist_test_check(int nr_expect) 184 { 185 struct plist_node *first, *prio_pos, *node_pos; 186 187 if (plist_head_empty(&test_head)) { 188 BUG_ON(nr_expect != 0); 189 return; 190 } 191 192 prio_pos = first = plist_first(&test_head); 193 plist_for_each(node_pos, &test_head) { 194 if (nr_expect-- < 0) 195 break; 196 if (node_pos == first) 197 continue; 198 if (node_pos->prio == prio_pos->prio) { 199 BUG_ON(!list_empty(&node_pos->prio_list)); 200 continue; 201 } 202 203 BUG_ON(prio_pos->prio > node_pos->prio); 204 BUG_ON(prio_pos->prio_list.next != &node_pos->prio_list); 205 prio_pos = node_pos; 206 } 207 208 BUG_ON(nr_expect != 0); 209 BUG_ON(prio_pos->prio_list.next != &first->prio_list); 210 } 211 212 static void __init plist_test_requeue(struct plist_node *node) 213 { 214 plist_requeue(node, &test_head); 215 216 if (node != plist_last(&test_head)) 217 BUG_ON(node->prio == plist_next(node)->prio); 218 } 219 220 static int __init plist_test(void) 221 { 222 int nr_expect = 0, i, loop; 223 unsigned int r = local_clock(); 224 225 printk(KERN_DEBUG "start plist test\n"); 226 plist_head_init(&test_head); 227 for (i = 0; i < ARRAY_SIZE(test_node); i++) 228 plist_node_init(test_node + i, 0); 229 230 for (loop = 0; loop < 1000; loop++) { 231 r = r * 193939 % 47629; 232 i = r % ARRAY_SIZE(test_node); 233 if (plist_node_empty(test_node + i)) { 234 r = r * 193939 % 47629; 235 test_node[i].prio = r % 99; 236 plist_add(test_node + i, &test_head); 237 nr_expect++; 238 } else { 239 plist_del(test_node + i, &test_head); 240 nr_expect--; 241 } 242 plist_test_check(nr_expect); 243 if (!plist_node_empty(test_node + i)) { 244 plist_test_requeue(test_node + i); 245 plist_test_check(nr_expect); 246 } 247 } 248 249 for (i = 0; i < ARRAY_SIZE(test_node); i++) { 250 if (plist_node_empty(test_node + i)) 251 continue; 252 plist_del(test_node + i, &test_head); 253 nr_expect--; 254 plist_test_check(nr_expect); 255 } 256 257 printk(KERN_DEBUG "end plist test\n"); 258 return 0; 259 } 260 261 module_init(plist_test); 262 263 #endif 264