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