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