lib/list_debug.c

   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 "
  25                         "prev (%p), but was %p. (next=%p).\n",
  26                         prev, next->prev, next);
  27                 BUG();
  28         }
  29         if (unlikely(prev->next != next)) {
  30                 printk(KERN_ERR "list_add corruption. prev->next should be "
  31                         "next (%p), but was %p. (prev=%p).\n",
  32                         next, prev->next, prev);
  33                 BUG();
  34         }
  35         next->prev = new;
  36         new->next = next;
  37         new->prev = prev;
  38         prev->next = new;
  39 }
  40 EXPORT_SYMBOL(__list_add);
  41
  42 /**
  43  * list_add - add a new entry
  44  * @new: new entry to be added
  45  * @head: list head to add it after
  46  *
  47  * Insert a new entry after the specified head.
  48  * This is good for implementing stacks.
  49  */
  50 void list_add(struct list_head *new, struct list_head *head)
  51 {
  52         __list_add(new, head, head->next);
  53 }
  54 EXPORT_SYMBOL(list_add);
  55
  56 /**
  57  * list_del - deletes entry from list.
  58  * @entry: the element to delete from the list.
  59  * Note: list_empty on entry does not return true after this, the entry is
  60  * in an undefined state.
  61  */
  62 void list_del(struct list_head *entry)
  63 {
  64         if (unlikely(entry->prev->next != entry)) {
  65                 printk(KERN_ERR "list_del corruption. prev->next should be %p, "
  66                                 "but was %p\n", entry, entry->prev->next);
  67                 BUG();
  68         }
  69         if (unlikely(entry->next->prev != entry)) {
  70                 printk(KERN_ERR "list_del corruption. next->prev should be %p, "
  71                                 "but was %p\n", entry, entry->next->prev);
  72                 BUG();
  73         }
  74         __list_del(entry->prev, entry->next);
  75         entry->next = LIST_POISON1;
  76         entry->prev = LIST_POISON2;
  77 }
  78 EXPORT_SYMBOL(list_del);