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/export.h> 10 #include <linux/list.h> 11 #include <linux/bug.h> 12 #include <linux/kernel.h> 13 #include <linux/rculist.h> 14 15 static struct list_head force_poison; 16 void list_force_poison(struct list_head *entry) 17 { 18 entry->next = &force_poison; 19 entry->prev = &force_poison; 20 } 21 22 /* 23 * Insert a new entry between two known consecutive entries. 24 * 25 * This is only for internal list manipulation where we know 26 * the prev/next entries already! 27 */ 28 29 void __list_add(struct list_head *new, 30 struct list_head *prev, 31 struct list_head *next) 32 { 33 WARN(new->next == &force_poison || new->prev == &force_poison, 34 "list_add attempted on force-poisoned entry\n"); 35 WARN(next->prev != prev, 36 "list_add corruption. next->prev should be " 37 "prev (%p), but was %p. (next=%p).\n", 38 prev, next->prev, next); 39 WARN(prev->next != next, 40 "list_add corruption. prev->next should be " 41 "next (%p), but was %p. (prev=%p).\n", 42 next, prev->next, prev); 43 WARN(new == prev || new == next, 44 "list_add double add: new=%p, prev=%p, next=%p.\n", 45 new, prev, next); 46 next->prev = new; 47 new->next = next; 48 new->prev = prev; 49 WRITE_ONCE(prev->next, new); 50 } 51 EXPORT_SYMBOL(__list_add); 52 53 void __list_del_entry(struct list_head *entry) 54 { 55 struct list_head *prev, *next; 56 57 prev = entry->prev; 58 next = entry->next; 59 60 if (WARN(next == LIST_POISON1, 61 "list_del corruption, %p->next is LIST_POISON1 (%p)\n", 62 entry, LIST_POISON1) || 63 WARN(prev == LIST_POISON2, 64 "list_del corruption, %p->prev is LIST_POISON2 (%p)\n", 65 entry, LIST_POISON2) || 66 WARN(prev->next != entry, 67 "list_del corruption. prev->next should be %p, " 68 "but was %p\n", entry, prev->next) || 69 WARN(next->prev != entry, 70 "list_del corruption. next->prev should be %p, " 71 "but was %p\n", entry, next->prev)) 72 return; 73 74 __list_del(prev, next); 75 } 76 EXPORT_SYMBOL(__list_del_entry); 77 78 /** 79 * list_del - deletes entry from list. 80 * @entry: the element to delete from the list. 81 * Note: list_empty on entry does not return true after this, the entry is 82 * in an undefined state. 83 */ 84 void list_del(struct list_head *entry) 85 { 86 __list_del_entry(entry); 87 entry->next = LIST_POISON1; 88 entry->prev = LIST_POISON2; 89 } 90 EXPORT_SYMBOL(list_del); 91 92 /* 93 * RCU variants. 94 */ 95 void __list_add_rcu(struct list_head *new, 96 struct list_head *prev, struct list_head *next) 97 { 98 WARN(next->prev != prev, 99 "list_add_rcu corruption. next->prev should be prev (%p), but was %p. (next=%p).\n", 100 prev, next->prev, next); 101 WARN(prev->next != next, 102 "list_add_rcu corruption. prev->next should be next (%p), but was %p. (prev=%p).\n", 103 next, prev->next, prev); 104 new->next = next; 105 new->prev = prev; 106 rcu_assign_pointer(list_next_rcu(prev), new); 107 next->prev = new; 108 } 109 EXPORT_SYMBOL(__list_add_rcu); 110