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1 #ifndef _LIST_H
2 #define _LIST_H
3 
4 /* Stripped down implementation of linked list taken
5  * from the Linux Kernel.
6  */
7 
8 /*
9  * Simple doubly linked list implementation.
10  *
11  * Some of the internal functions ("__xxx") are useful when
12  * manipulating whole lists rather than single entries, as
13  * sometimes we already know the next/prev entries and we can
14  * generate better code by using them directly rather than
15  * using the generic single-entry routines.
16  */
17 
18 struct list_head {
19 	struct list_head *next, *prev;
20 };
21 
22 #define LIST_HEAD_INIT(name) { &(name), &(name) }
23 
24 #define LIST_HEAD(name) \
25 	struct list_head name = LIST_HEAD_INIT(name)
26 
INIT_LIST_HEAD(struct list_head * list)27 static inline void INIT_LIST_HEAD(struct list_head *list)
28 {
29 	list->next = list;
30 	list->prev = list;
31 }
32 
33 /*
34  * Insert a new entry between two known consecutive entries.
35  *
36  * This is only for internal list manipulation where we know
37  * the prev/next entries already!
38  */
__list_add(struct list_head * new,struct list_head * prev,struct list_head * next)39 static inline void __list_add(struct list_head *new,
40 			      struct list_head *prev,
41 			      struct list_head *next)
42 {
43 	next->prev = new;
44 	new->next = next;
45 	new->prev = prev;
46 	prev->next = new;
47 }
48 
49 /**
50  * list_add - add a new entry
51  * @new: new entry to be added
52  * @head: list head to add it after
53  *
54  * Insert a new entry after the specified head.
55  * This is good for implementing stacks.
56  */
list_add(struct list_head * new,struct list_head * head)57 static inline void list_add(struct list_head *new, struct list_head *head)
58 {
59 	__list_add(new, head, head->next);
60 }
61 
62 /*
63  * Delete a list entry by making the prev/next entries
64  * point to each other.
65  *
66  * This is only for internal list manipulation where we know
67  * the prev/next entries already!
68  */
__list_del(struct list_head * prev,struct list_head * next)69 static inline void __list_del(struct list_head * prev, struct list_head * next)
70 {
71 	next->prev = prev;
72 	prev->next = next;
73 }
74 
75 #define POISON_POINTER_DELTA 0
76 #define LIST_POISON1  ((void *) 0x00100100 + POISON_POINTER_DELTA)
77 #define LIST_POISON2  ((void *) 0x00200200 + POISON_POINTER_DELTA)
78 
79 /**
80  * list_del - deletes entry from list.
81  * @entry: the element to delete from the list.
82  * Note: list_empty() on entry does not return true after this, the entry is
83  * in an undefined state.
84  */
__list_del_entry(struct list_head * entry)85 static inline void __list_del_entry(struct list_head *entry)
86 {
87 	__list_del(entry->prev, entry->next);
88 }
89 
list_del(struct list_head * entry)90 static inline void list_del(struct list_head *entry)
91 {
92 	__list_del(entry->prev, entry->next);
93 	entry->next = LIST_POISON1;
94 	entry->prev = LIST_POISON2;
95 }
96 
97 /**
98  * list_entry - get the struct for this entry
99  * @ptr:	the &struct list_head pointer.
100  * @type:	the type of the struct this is embedded in.
101  * @member:	the name of the list_head within the struct.
102  */
103 #define list_entry(ptr, type, member) \
104 	container_of(ptr, type, member)
105 /**
106  * list_for_each	-	iterate over a list
107  * @pos:	the &struct list_head to use as a loop cursor.
108  * @head:	the head for your list.
109  */
110 #define list_for_each(pos, head) \
111 	for (pos = (head)->next; pos != (head); pos = pos->next)
112 
113 /**
114  * list_for_each_safe - iterate over a list safe against removal of list entry
115  * @pos:	the &struct list_head to use as a loop cursor.
116  * @n:		another &struct list_head to use as temporary storage
117  * @head:	the head for your list.
118  */
119 #define list_for_each_safe(pos, n, head) \
120 	for (pos = (head)->next, n = pos->next; pos != (head); \
121 		pos = n, n = pos->next)
122 
123 #define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
124 
125 /**
126  * container_of - cast a member of a structure out to the containing structure
127  * @ptr:	the pointer to the member.
128  * @type:	the type of the container struct this is embedded in.
129  * @member:	the name of the member within the struct.
130  *
131  */
132 #define container_of(ptr, type, member) ({			\
133 	const typeof( ((type *)0)->member ) *__mptr = (ptr);	\
134 	(type *)( (char *)__mptr - offsetof(type,member) );})
135 
136 #endif
137