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/export.h>
  10 #include <linux/list.h>
  11 #include <linux/bug.h>
  12 #include <linux/kernel.h>
  13
  14 /*
  15  * Insert a new entry between two known consecutive entries.
  16  *
  17  * This is only for internal list manipulation where we know
  18  * the prev/next entries already!
  19  */
  20
  21 void __list_add(struct list_head *new,
  22                               struct list_head *prev,
  23                               struct list_head *next)
  24 {
  25         WARN(next->prev != prev,
  26                 "list_add corruption. next->prev should be "
  27                 "prev (%p), but was %p. (next=%p).\n",
  28                 prev, next->prev, next);
  29         WARN(prev->next != next,
  30                 "list_add corruption. prev->next should be "
  31                 "next (%p), but was %p. (prev=%p).\n",
  32                 next, prev->next, prev);
  33         next->prev = new;
  34         new->next = next;
  35         new->prev = prev;
  36         prev->next = new;
  37 }
  38 EXPORT_SYMBOL(__list_add);
  39
  40 void __list_del_entry(struct list_head *entry)
  41 {
  42         struct list_head *prev, *next;
  43
  44         prev = entry->prev;
  45         next = entry->next;
  46
  47         if (WARN(next == LIST_POISON1,
  48                 "list_del corruption, %p->next is LIST_POISON1 (%p)\n",
  49                 entry, LIST_POISON1) ||
  50             WARN(prev == LIST_POISON2,
  51                 "list_del corruption, %p->prev is LIST_POISON2 (%p)\n",
  52                 entry, LIST_POISON2) ||
  53             WARN(prev->next != entry,
  54                 "list_del corruption. prev->next should be %p, "
  55                 "but was %p\n", entry, prev->next) ||
  56             WARN(next->prev != entry,
  57                 "list_del corruption. next->prev should be %p, "
  58                 "but was %p\n", entry, next->prev))
  59                 return;
  60
  61         __list_del(prev, next);
  62 }
  63 EXPORT_SYMBOL(__list_del_entry);
  64
  65 /**
  66  * list_del - deletes entry from list.
  67  * @entry: the element to delete from the list.
  68  * Note: list_empty on entry does not return true after this, the entry is
  69  * in an undefined state.
  70  */
  71 void list_del(struct list_head *entry)
  72 {
  73         __list_del_entry(entry);
  74         entry->next = LIST_POISON1;
  75         entry->prev = LIST_POISON2;
  76 }
  77 EXPORT_SYMBOL(list_del);