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