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 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 #ifdef CONFIG_DEBUG_PI_LIST 137 #include <linux/sched.h> 138 #include <linux/module.h> 139 #include <linux/init.h> 140 141 static struct plist_node __initdata test_node[241]; 142 143 static 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 } 171 172 static 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 } 208 209 module_init(plist_test); 210 211 #endif 212