Root/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
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    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

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