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 #include <linux/rculist.h>
  14
  15 /*
  16  * Insert a new entry between two known consecutive entries.
  17  *
  18  * This is only for internal list manipulation where we know
  19  * the prev/next entries already!
  20  */
  21
  22 void __list_add(struct list_head *new,
  23                               struct list_head *prev,
  24                               struct list_head *next)
  25 {
  26         if (WARN(next->prev != prev,
  27                 "list_add corruption. next->prev should be "
  28                 "prev (%p), but was %p. (next=%p).\n",
  29                 prev, next->prev, next) ||
  30             WARN(prev->next != next,
  31                 "list_add corruption. prev->next should be "
  32                 "next (%p), but was %p. (prev=%p).\n",
  33                 next, prev->next, prev) ||
  34             WARN(new == prev || new == next,
  35                  "list_add double add: new=%p, prev=%p, next=%p.\n",
  36                  new, prev, next))
  37                 BUG_ON(1);
  38
  39         next->prev = new;
  40         new->next = next;
  41         new->prev = prev;
  42         prev->next = new;
  43 }
  44 EXPORT_SYMBOL(__list_add);
  45
  46 void __list_del_entry(struct list_head *entry)
  47 {
  48         struct list_head *prev, *next;
  49
  50         prev = entry->prev;
  51         next = entry->next;
  52
  53         if (WARN(next == LIST_POISON1,
  54                 "list_del corruption, %p->next is LIST_POISON1 (%p)\n",
  55                 entry, LIST_POISON1) ||
  56             WARN(prev == LIST_POISON2,
  57                 "list_del corruption, %p->prev is LIST_POISON2 (%p)\n",
  58                 entry, LIST_POISON2) ||
  59             WARN(prev->next != entry,
  60                 "list_del corruption. prev->next should be %p, "
  61                 "but was %p\n", entry, prev->next) ||
  62             WARN(next->prev != entry,
  63                 "list_del corruption. next->prev should be %p, "
  64                 "but was %p\n", entry, next->prev))
  65                 BUG_ON(1);
  66
  67         __list_del(prev, next);
  68 }
  69 EXPORT_SYMBOL(__list_del_entry);
  70
  71 /**
  72  * list_del - deletes entry from list.
  73  * @entry: the element to delete from the list.
  74  * Note: list_empty on entry does not return true after this, the entry is
  75  * in an undefined state.
  76  */
  77 void list_del(struct list_head *entry)
  78 {
  79         __list_del_entry(entry);
  80         entry->next = LIST_POISON1;
  81         entry->prev = LIST_POISON2;
  82 }
  83 EXPORT_SYMBOL(list_del);
  84
  85 /*
  86  * RCU variants.
  87  */
  88 void __list_add_rcu(struct list_head *new,
  89                     struct list_head *prev, struct list_head *next)
  90 {
  91         if (WARN(next->prev != prev,
  92                 "list_add_rcu corruption. next->prev should be prev (%p), but was %p. (next=%p).\n",
  93                 prev, next->prev, next) ||
  94             WARN(prev->next != next,
  95                 "list_add_rcu corruption. prev->next should be next (%p), but was %p. (prev=%p).\n",
  96                 next, prev->next, prev))
  97                 BUG_ON(1);
  98
  99         new->next = next;
 100         new->prev = prev;
 101         rcu_assign_pointer(list_next_rcu(prev), new);
 102         next->prev = new;
 103 }
 104 EXPORT_SYMBOL(__list_add_rcu);