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