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 %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         if (unlikely(entry->prev->next != entry)) {
  63                 printk(KERN_ERR "list_del corruption. prev->next should be %p, "
  64                                 "but was %p\n", entry, entry->prev->next);
  65                 BUG();
  66         }
  67         if (unlikely(entry->next->prev != entry)) {
  68                 printk(KERN_ERR "list_del corruption. next->prev should be %p, "
  69                                 "but was %p\n", entry, entry->next->prev);
  70                 BUG();
  71         }
  72         __list_del(entry->prev, entry->next);
  73         entry->next = LIST_POISON1;
  74         entry->prev = LIST_POISON2;
  75 }
  76 EXPORT_SYMBOL(list_del);