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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
19struct 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
28static 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 */
40static 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 */
58static 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 */
70static 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
80static 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 */
91static 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