1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LIST_H
3 #define _LIST_H
4 
5 /* Stripped down implementation of linked list taken
6  * from the Linux Kernel.
7  */
8 
9 /*
10  * Simple doubly linked list implementation.
11  *
12  * Some of the internal functions ("__xxx") are useful when
13  * manipulating whole lists rather than single entries, as
14  * sometimes we already know the next/prev entries and we can
15  * generate better code by using them directly rather than
16  * using the generic single-entry routines.
17  */
18 
19 struct list_head {
20 	struct list_head *next, *prev;
21 };
22 
23 #define LIST_HEAD_INIT(name) { &(name), &(name) }
24 
25 #define LIST_HEAD(name) \
26 	struct list_head name = LIST_HEAD_INIT(name)
27 
INIT_LIST_HEAD(struct list_head * list)28 static inline void INIT_LIST_HEAD(struct list_head *list)
29 {
30 	list->next = list;
31 	list->prev = list;
32 }
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 * new,struct list_head * prev,struct list_head * next)40 static inline void __list_add(struct list_head *new,
41 			      struct list_head *prev,
42 			      struct list_head *next)
43 {
44 	next->prev = new;
45 	new->next = next;
46 	new->prev = prev;
47 	prev->next = new;
48 }
49 
50 /**
51  * list_add - add a new entry
52  * @new: 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 * new,struct list_head * head)58 static inline void list_add(struct list_head *new, struct list_head *head)
59 {
60 	__list_add(new, head, head->next);
61 }
62 
63 /*
64  * Delete a list entry by making the prev/next entries
65  * point to each other.
66  *
67  * This is only for internal list manipulation where we know
68  * the prev/next entries already!
69  */
__list_del(struct list_head * prev,struct list_head * next)70 static inline void __list_del(struct list_head * prev, struct list_head * next)
71 {
72 	next->prev = prev;
73 	prev->next = next;
74 }
75 
76 #define POISON_POINTER_DELTA 0
77 #define LIST_POISON1  ((void *) 0x00100100 + POISON_POINTER_DELTA)
78 #define LIST_POISON2  ((void *) 0x00200200 + POISON_POINTER_DELTA)
79 
__list_del_entry(struct list_head * entry)80 static inline void __list_del_entry(struct list_head *entry)
81 {
82 	__list_del(entry->prev, entry->next);
83 }
84 
85 /**
86  * list_del - deletes entry from list.
87  * @entry: the element to delete from the list.
88  * Note: list_empty() on entry does not return true after this, the entry is
89  * in an undefined state.
90  */
list_del(struct list_head * entry)91 static inline void list_del(struct list_head *entry)
92 {
93 	__list_del(entry->prev, entry->next);
94 	entry->next = LIST_POISON1;
95 	entry->prev = LIST_POISON2;
96 }
97 
98 /**
99  * list_entry - get the struct for this entry
100  * @ptr:	the &struct list_head pointer.
101  * @type:	the type of the struct this is embedded in.
102  * @member:	the name of the list_head within the struct.
103  */
104 #define list_entry(ptr, type, member) \
105 	container_of(ptr, type, member)
106 /**
107  * list_for_each	-	iterate over a list
108  * @pos:	the &struct list_head to use as a loop cursor.
109  * @head:	the head for your list.
110  */
111 #define list_for_each(pos, head) \
112 	for (pos = (head)->next; pos != (head); pos = pos->next)
113 
114 /**
115  * list_for_each_safe - iterate over a list safe against removal of list entry
116  * @pos:	the &struct list_head to use as a loop cursor.
117  * @n:		another &struct list_head to use as temporary storage
118  * @head:	the head for your list.
119  */
120 #define list_for_each_safe(pos, n, head) \
121 	for (pos = (head)->next, n = pos->next; pos != (head); \
122 		pos = n, n = pos->next)
123 
124 #define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
125 
126 /**
127  * container_of - cast a member of a structure out to the containing structure
128  * @ptr:	the pointer to the member.
129  * @type:	the type of the container struct this is embedded in.
130  * @member:	the name of the member within the struct.
131  *
132  */
133 #define container_of(ptr, type, member) ({			\
134 	const typeof( ((type *)0)->member ) *__mptr = (ptr);	\
135 	(type *)( (char *)__mptr - offsetof(type,member) );})
136 
137 #endif
138