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         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         next->prev = new;
  38         new->next = next;
  39         new->prev = prev;
  40         WRITE_ONCE(prev->next, new);
  41 }
  42 EXPORT_SYMBOL(__list_add);
  43
  44 void __list_del_entry(struct list_head *entry)
  45 {
  46         struct list_head *prev, *next;
  47
  48         prev = entry->prev;
  49         next = entry->next;
  50
  51         if (WARN(next == LIST_POISON1,
  52                 "list_del corruption, %p->next is LIST_POISON1 (%p)\n",
  53                 entry, LIST_POISON1) ||
  54             WARN(prev == LIST_POISON2,
  55                 "list_del corruption, %p->prev is LIST_POISON2 (%p)\n",
  56                 entry, LIST_POISON2) ||
  57             WARN(prev->next != entry,
  58                 "list_del corruption. prev->next should be %p, "
  59                 "but was %p\n", entry, prev->next) ||
  60             WARN(next->prev != entry,
  61                 "list_del corruption. next->prev should be %p, "
  62                 "but was %p\n", entry, next->prev))
  63                 return;
  64
  65         __list_del(prev, next);
  66 }
  67 EXPORT_SYMBOL(__list_del_entry);
  68
  69 /**
  70  * list_del - deletes entry from list.
  71  * @entry: the element to delete from the list.
  72  * Note: list_empty on entry does not return true after this, the entry is
  73  * in an undefined state.
  74  */
  75 void list_del(struct list_head *entry)
  76 {
  77         __list_del_entry(entry);
  78         entry->next = LIST_POISON1;
  79         entry->prev = LIST_POISON2;
  80 }
  81 EXPORT_SYMBOL(list_del);
  82
  83 /*
  84  * RCU variants.
  85  */
  86 void __list_add_rcu(struct list_head *new,
  87                     struct list_head *prev, struct list_head *next)
  88 {
  89         WARN(next->prev != prev,
  90                 "list_add_rcu corruption. next->prev should be prev (%p), but was %p. (next=%p).\n",
  91                 prev, next->prev, next);
  92         WARN(prev->next != next,
  93                 "list_add_rcu corruption. prev->next should be next (%p), but was %p. (prev=%p).\n",
  94                 next, prev->next, prev);
  95         new->next = next;
  96         new->prev = prev;
  97         rcu_assign_pointer(list_next_rcu(prev), new);
  98         next->prev = new;
  99 }
 100 EXPORT_SYMBOL(__list_add_rcu);