1 /* 2 * Copyright 2006, Red Hat, Inc., Dave Jones 3 * Released under the General Public License (GPL). 4 * 5 * This file contains the linked list implementations for 6 * DEBUG_LIST. 7 */ 8 9 #include <linux/module.h> 10 #include <linux/list.h> 11 12 /* 13 * Insert a new entry between two known consecutive entries. 14 * 15 * This is only for internal list manipulation where we know 16 * the prev/next entries already! 17 */ 18 19 void __list_add(struct list_head *new, 20 struct list_head *prev, 21 struct list_head *next) 22 { 23 if (unlikely(next->prev != prev)) { 24 printk(KERN_ERR "list_add corruption. next->prev should be %p, but was %p\n", 25 prev, next->prev); 26 BUG(); 27 } 28 if (unlikely(prev->next != next)) { 29 printk(KERN_ERR "list_add corruption. prev->next should be %p, but was %p\n", 30 next, prev->next); 31 BUG(); 32 } 33 next->prev = new; 34 new->next = next; 35 new->prev = prev; 36 prev->next = new; 37 } 38 EXPORT_SYMBOL(__list_add); 39 40 /** 41 * list_add - add a new entry 42 * @new: new entry to be added 43 * @head: list head to add it after 44 * 45 * Insert a new entry after the specified head. 46 * This is good for implementing stacks. 47 */ 48 void list_add(struct list_head *new, struct list_head *head) 49 { 50 __list_add(new, head, head->next); 51 } 52 EXPORT_SYMBOL(list_add); 53 54 /** 55 * list_del - deletes entry from list. 56 * @entry: the element to delete from the list. 57 * Note: list_empty on entry does not return true after this, the entry is 58 * in an undefined state. 59 */ 60 void list_del(struct list_head *entry) 61 { 62 BUG_ON(entry->prev->next != entry); 63 BUG_ON(entry->next->prev != entry); 64 65 if (unlikely(entry->prev->next != entry)) { 66 printk(KERN_ERR "list_del corruption. prev->next should be %p, " 67 "but was %p\n", entry, entry->prev->next); 68 BUG(); 69 } 70 if (unlikely(entry->next->prev != entry)) { 71 printk(KERN_ERR "list_del corruption. next->prev should be %p, " 72 "but was %p\n", entry, entry->next->prev); 73 BUG(); 74 } 75 __list_del(entry->prev, entry->next); 76 entry->next = LIST_POISON1; 77 entry->prev = LIST_POISON2; 78 } 79 EXPORT_SYMBOL(list_del); 80