blob: 04d61a19baddaed01dc4280a399b5eb25dbe74c5
1 | /* vi: set sw=4 ts=4: */ |
2 | |
3 | #include "list.h" |
4 | |
5 | /* |
6 | * Insert a new entry between two known consecutive entries. |
7 | * |
8 | * This is only for internal list manipulation where we know |
9 | * the prev/next entries already! |
10 | */ |
11 | void __list_add(struct list_head * add, |
12 | struct list_head * prev, |
13 | struct list_head * next) |
14 | { |
15 | next->prev = add; |
16 | add->next = next; |
17 | add->prev = prev; |
18 | prev->next = add; |
19 | } |
20 | |
21 | /* |
22 | * list_add - add a new entry |
23 | * @add: new entry to be added |
24 | * @head: list head to add it after |
25 | * |
26 | * Insert a new entry after the specified head. |
27 | * This is good for implementing stacks. |
28 | */ |
29 | void list_add(struct list_head *add, struct list_head *head) |
30 | { |
31 | __list_add(add, head, head->next); |
32 | } |
33 | |
34 | /* |
35 | * list_add_tail - add a new entry |
36 | * @add: new entry to be added |
37 | * @head: list head to add it before |
38 | * |
39 | * Insert a new entry before the specified head. |
40 | * This is useful for implementing queues. |
41 | */ |
42 | void list_add_tail(struct list_head *add, struct list_head *head) |
43 | { |
44 | __list_add(add, head->prev, head); |
45 | } |
46 | |
47 | /* |
48 | * Delete a list entry by making the prev/next entries |
49 | * point to each other. |
50 | * |
51 | * This is only for internal list manipulation where we know |
52 | * the prev/next entries already! |
53 | */ |
54 | void __list_del(struct list_head * prev, struct list_head * next) |
55 | { |
56 | next->prev = prev; |
57 | prev->next = next; |
58 | } |
59 | |
60 | /* |
61 | * list_del - deletes entry from list. |
62 | * @entry: the element to delete from the list. |
63 | * |
64 | * list_empty() on @entry does not return true after this, @entry is |
65 | * in an undefined state. |
66 | */ |
67 | void list_del(struct list_head *entry) |
68 | { |
69 | __list_del(entry->prev, entry->next); |
70 | } |
71 | |
72 | /* |
73 | * list_del_init - deletes entry from list and reinitialize it. |
74 | * @entry: the element to delete from the list. |
75 | */ |
76 | void list_del_init(struct list_head *entry) |
77 | { |
78 | __list_del(entry->prev, entry->next); |
79 | INIT_LIST_HEAD(entry); |
80 | } |
81 | |
82 | /* |
83 | * list_empty - tests whether a list is empty |
84 | * @head: the list to test. |
85 | */ |
86 | int list_empty(struct list_head *head) |
87 | { |
88 | return head->next == head; |
89 | } |
90 | |
91 | /* |
92 | * list_splice - join two lists |
93 | * @list: the new list to add. |
94 | * @head: the place to add it in the first list. |
95 | */ |
96 | void list_splice(struct list_head *list, struct list_head *head) |
97 | { |
98 | struct list_head *first = list->next; |
99 | |
100 | if (first != list) { |
101 | struct list_head *last = list->prev; |
102 | struct list_head *at = head->next; |
103 | |
104 | first->prev = head; |
105 | head->next = first; |
106 | |
107 | last->next = at; |
108 | at->prev = last; |
109 | } |
110 | } |
111 |