LXR linux/lib/list

   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
  22void __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}
  42EXPORT_SYMBOL(__list_add);
  43
  44void __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}
  67EXPORT_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 */
  75void list_del(struct list_head *entry)
  76{
  77        __list_del_entry(entry);
  78        entry->next = LIST_POISON1;
  79        entry->prev = LIST_POISON2;
  80}
  81EXPORT_SYMBOL(list_del);
  82
  83/*
  84 * RCU variants.
  85 */
  86void __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}
 100EXPORT_SYMBOL(__list_add_rcu);
 101