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 pr_debug("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 pr_debug("end plist test\n"); 207 return 0; 208 } 209 210 module_init(plist_test); 211 212 #endif 213