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 WARN_ON(head != &test_head && !head->rawlock && !head->spinlock); 60 if (head->rawlock) 61 WARN_ON_SMP(!raw_spin_is_locked(head->rawlock)); 62 if (head->spinlock) 63 WARN_ON_SMP(!spin_is_locked(head->spinlock)); 64 if (!plist_head_empty(head)) 65 plist_check_list(&plist_first(head)->prio_list); 66 plist_check_list(&head->node_list); 67 } 68 69 #else 70 # define plist_check_head(h) do { } while (0) 71 #endif 72 73 /** 74 * plist_add - add @node to @head 75 * 76 * @node: &struct plist_node pointer 77 * @head: &struct plist_head pointer 78 */ 79 void plist_add(struct plist_node *node, struct plist_head *head) 80 { 81 struct plist_node *first, *iter, *prev = NULL; 82 struct list_head *node_next = &head->node_list; 83 84 plist_check_head(head); 85 WARN_ON(!plist_node_empty(node)); 86 WARN_ON(!list_empty(&node->prio_list)); 87 88 if (plist_head_empty(head)) 89 goto ins_node; 90 91 first = iter = plist_first(head); 92 93 do { 94 if (node->prio < iter->prio) { 95 node_next = &iter->node_list; 96 break; 97 } 98 99 prev = iter; 100 iter = list_entry(iter->prio_list.next, 101 struct plist_node, prio_list); 102 } while (iter != first); 103 104 if (!prev || prev->prio != node->prio) 105 list_add_tail(&node->prio_list, &iter->prio_list); 106 ins_node: 107 list_add_tail(&node->node_list, node_next); 108 109 plist_check_head(head); 110 } 111 112 /** 113 * plist_del - Remove a @node from plist. 114 * 115 * @node: &struct plist_node pointer - entry to be removed 116 * @head: &struct plist_head pointer - list head 117 */ 118 void plist_del(struct plist_node *node, struct plist_head *head) 119 { 120 plist_check_head(head); 121 122 if (!list_empty(&node->prio_list)) { 123 if (node->node_list.next != &head->node_list) { 124 struct plist_node *next; 125 126 next = list_entry(node->node_list.next, 127 struct plist_node, node_list); 128 129 /* add the next plist_node into prio_list */ 130 if (list_empty(&next->prio_list)) 131 list_add(&next->prio_list, &node->prio_list); 132 } 133 list_del_init(&node->prio_list); 134 } 135 136 list_del_init(&node->node_list); 137 138 plist_check_head(head); 139 } 140 141 #ifdef CONFIG_DEBUG_PI_LIST 142 #include <linux/sched.h> 143 #include <linux/module.h> 144 #include <linux/init.h> 145 146 static struct plist_node __initdata test_node[241]; 147 148 static void __init plist_test_check(int nr_expect) 149 { 150 struct plist_node *first, *prio_pos, *node_pos; 151 152 if (plist_head_empty(&test_head)) { 153 BUG_ON(nr_expect != 0); 154 return; 155 } 156 157 prio_pos = first = plist_first(&test_head); 158 plist_for_each(node_pos, &test_head) { 159 if (nr_expect-- < 0) 160 break; 161 if (node_pos == first) 162 continue; 163 if (node_pos->prio == prio_pos->prio) { 164 BUG_ON(!list_empty(&node_pos->prio_list)); 165 continue; 166 } 167 168 BUG_ON(prio_pos->prio > node_pos->prio); 169 BUG_ON(prio_pos->prio_list.next != &node_pos->prio_list); 170 prio_pos = node_pos; 171 } 172 173 BUG_ON(nr_expect != 0); 174 BUG_ON(prio_pos->prio_list.next != &first->prio_list); 175 } 176 177 static int __init plist_test(void) 178 { 179 int nr_expect = 0, i, loop; 180 unsigned int r = local_clock(); 181 182 printk(KERN_INFO "start plist test\n"); 183 plist_head_init(&test_head, NULL); 184 for (i = 0; i < ARRAY_SIZE(test_node); i++) 185 plist_node_init(test_node + i, 0); 186 187 for (loop = 0; loop < 1000; loop++) { 188 r = r * 193939 % 47629; 189 i = r % ARRAY_SIZE(test_node); 190 if (plist_node_empty(test_node + i)) { 191 r = r * 193939 % 47629; 192 test_node[i].prio = r % 99; 193 plist_add(test_node + i, &test_head); 194 nr_expect++; 195 } else { 196 plist_del(test_node + i, &test_head); 197 nr_expect--; 198 } 199 plist_test_check(nr_expect); 200 } 201 202 for (i = 0; i < ARRAY_SIZE(test_node); i++) { 203 if (plist_node_empty(test_node + i)) 204 continue; 205 plist_del(test_node + i, &test_head); 206 nr_expect--; 207 plist_test_check(nr_expect); 208 } 209 210 printk(KERN_INFO "end plist test\n"); 211 return 0; 212 } 213 214 module_init(plist_test); 215 216 #endif 217