1 #if !defined(_BLKID_LIST_H) && !defined(LIST_HEAD)
2 #define _BLKID_LIST_H
3
4 #ifdef __cplusplus
5 extern "C" {
6 #endif
7
8 #ifdef __GNUC__
9 #define _INLINE_ static __inline__
10 #else /* For Watcom C */
11 #define _INLINE_ static inline
12 #endif
13
14 /*
15 * Simple doubly linked list implementation.
16 *
17 * Some of the internal functions ("__xxx") are useful when
18 * manipulating whole lists rather than single entries, as
19 * sometimes we already know the next/prev entries and we can
20 * generate better code by using them directly rather than
21 * using the generic single-entry routines.
22 */
23
24 struct list_head {
25 struct list_head *next, *prev;
26 };
27
28 #define LIST_HEAD_INIT(name) { &(name), &(name) }
29
30 #define LIST_HEAD(name) \
31 struct list_head name = LIST_HEAD_INIT(name)
32
33 #define INIT_LIST_HEAD(ptr) do { \
34 (ptr)->next = (ptr); (ptr)->prev = (ptr); \
35 } while (0)
36
37 /*
38 * Insert a new entry between two known consecutive entries.
39 *
40 * This is only for internal list manipulation where we know
41 * the prev/next entries already!
42 */
__list_add(struct list_head * add,struct list_head * prev,struct list_head * next)43 _INLINE_ void __list_add(struct list_head * add,
44 struct list_head * prev,
45 struct list_head * next)
46 {
47 next->prev = add;
48 add->next = next;
49 add->prev = prev;
50 prev->next = add;
51 }
52
53 /**
54 * list_add - add a new entry
55 * @add: new entry to be added
56 * @head: list head to add it after
57 *
58 * Insert a new entry after the specified head.
59 * This is good for implementing stacks.
60 */
list_add(struct list_head * add,struct list_head * head)61 _INLINE_ void list_add(struct list_head *add, struct list_head *head)
62 {
63 __list_add(add, head, head->next);
64 }
65
66 /**
67 * list_add_tail - add a new entry
68 * @add: new entry to be added
69 * @head: list head to add it before
70 *
71 * Insert a new entry before the specified head.
72 * This is useful for implementing queues.
73 */
list_add_tail(struct list_head * add,struct list_head * head)74 _INLINE_ void list_add_tail(struct list_head *add, struct list_head *head)
75 {
76 __list_add(add, head->prev, head);
77 }
78
79 /*
80 * Delete a list entry by making the prev/next entries
81 * point to each other.
82 *
83 * This is only for internal list manipulation where we know
84 * the prev/next entries already!
85 */
__list_del(struct list_head * prev,struct list_head * next)86 _INLINE_ void __list_del(struct list_head * prev,
87 struct list_head * next)
88 {
89 next->prev = prev;
90 prev->next = next;
91 }
92
93 /**
94 * list_del - deletes entry from list.
95 * @entry: the element to delete from the list.
96 *
97 * list_empty() on @entry does not return true after this, @entry is
98 * in an undefined state.
99 */
list_del(struct list_head * entry)100 _INLINE_ void list_del(struct list_head *entry)
101 {
102 __list_del(entry->prev, entry->next);
103 }
104
105 /**
106 * list_del_init - deletes entry from list and reinitialize it.
107 * @entry: the element to delete from the list.
108 */
list_del_init(struct list_head * entry)109 _INLINE_ void list_del_init(struct list_head *entry)
110 {
111 __list_del(entry->prev, entry->next);
112 INIT_LIST_HEAD(entry);
113 }
114
115 /**
116 * list_empty - tests whether a list is empty
117 * @head: the list to test.
118 */
list_empty(struct list_head * head)119 _INLINE_ int list_empty(struct list_head *head)
120 {
121 return head->next == head;
122 }
123
124 /**
125 * list_splice - join two lists
126 * @list: the new list to add.
127 * @head: the place to add it in the first list.
128 */
list_splice(struct list_head * list,struct list_head * head)129 _INLINE_ void list_splice(struct list_head *list, struct list_head *head)
130 {
131 struct list_head *first = list->next;
132
133 if (first != list) {
134 struct list_head *last = list->prev;
135 struct list_head *at = head->next;
136
137 first->prev = head;
138 head->next = first;
139
140 last->next = at;
141 at->prev = last;
142 }
143 }
144
145 /**
146 * list_entry - get the struct for this entry
147 * @ptr: the &struct list_head pointer.
148 * @type: the type of the struct this is embedded in.
149 * @member: the name of the list_struct within the struct.
150 */
151 #define list_entry(ptr, type, member) \
152 ((type *)((char *)(ptr)-(unsigned long)(&((type *)0)->member)))
153
154 /**
155 * list_for_each - iterate over elements in a list
156 * @pos: the &struct list_head to use as a loop counter.
157 * @head: the head for your list.
158 */
159 #define list_for_each(pos, head) \
160 for (pos = (head)->next; pos != (head); pos = pos->next)
161
162 /**
163 * list_for_each_safe - iterate over elements in a list, but don't dereference
164 * pos after the body is done (in case it is freed)
165 * @pos: the &struct list_head to use as a loop counter.
166 * @pnext: the &struct list_head to use as a pointer to the next item.
167 * @head: the head for your list (not included in iteration).
168 */
169 #define list_for_each_safe(pos, pnext, head) \
170 for (pos = (head)->next, pnext = pos->next; pos != (head); \
171 pos = pnext, pnext = pos->next)
172
173 #undef _INLINE_
174
175 #ifdef __cplusplus
176 }
177 #endif
178
179 #endif /* _BLKID_LIST_H */
180