1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef LIST_H
3#define LIST_H
4
5#include <stddef.h>
6
7#include "list_types.h"
8
9/* Are two types/vars the same type (ignoring qualifiers)? */
10#define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
11
12/**
13 * container_of - cast a member of a structure out to the containing structure
14 * @ptr:	the pointer to the member.
15 * @type:	the type of the container struct this is embedded in.
16 * @member:	the name of the member within the struct.
17 *
18 */
19#define container_of(ptr, type, member) ({				\
20	void *__mptr = (void *)(ptr);					\
21	_Static_assert(__same_type(*(ptr), ((type *)0)->member) ||	\
22		      __same_type(*(ptr), void),			\
23		      "pointer type mismatch in container_of()");	\
24	((type *)(__mptr - offsetof(type, member))); })
25
26#define LIST_POISON1  ((void *) 0x100)
27#define LIST_POISON2  ((void *) 0x122)
28
29/*
30 * Circular doubly linked list implementation.
31 *
32 * Some of the internal functions ("__xxx") are useful when
33 * manipulating whole lists rather than single entries, as
34 * sometimes we already know the next/prev entries and we can
35 * generate better code by using them directly rather than
36 * using the generic single-entry routines.
37 */
38
39#define LIST_HEAD_INIT(name) { &(name), &(name) }
40
41#define LIST_HEAD(name) \
42	struct list_head name = LIST_HEAD_INIT(name)
43
44/**
45 * INIT_LIST_HEAD - Initialize a list_head structure
46 * @list: list_head structure to be initialized.
47 *
48 * Initializes the list_head to point to itself.  If it is a list header,
49 * the result is an empty list.
50 */
51static inline void INIT_LIST_HEAD(struct list_head *list)
52{
53	list->next = list;
54	list->prev = list;
55}
56
57/*
58 * Insert a new entry between two known consecutive entries.
59 *
60 * This is only for internal list manipulation where we know
61 * the prev/next entries already!
62 */
63static inline void __list_add(struct list_head *new,
64			      struct list_head *prev,
65			      struct list_head *next)
66{
67	next->prev = new;
68	new->next = next;
69	new->prev = prev;
70	prev->next = new;
71}
72
73/**
74 * list_add - add a new entry
75 * @new: new entry to be added
76 * @head: list head to add it after
77 *
78 * Insert a new entry after the specified head.
79 * This is good for implementing stacks.
80 */
81static inline void list_add(struct list_head *new, struct list_head *head)
82{
83	__list_add(new, head, head->next);
84}
85
86/**
87 * list_add_tail - add a new entry
88 * @new: new entry to be added
89 * @head: list head to add it before
90 *
91 * Insert a new entry before the specified head.
92 * This is useful for implementing queues.
93 */
94static inline void list_add_tail(struct list_head *new, struct list_head *head)
95{
96	__list_add(new, head->prev, head);
97}
98
99/*
100 * Delete a list entry by making the prev/next entries
101 * point to each other.
102 *
103 * This is only for internal list manipulation where we know
104 * the prev/next entries already!
105 */
106static inline void __list_del(struct list_head *prev, struct list_head *next)
107{
108	next->prev = prev;
109	prev->next = next;
110}
111
112static inline void __list_del_entry(struct list_head *entry)
113{
114	__list_del(entry->prev, entry->next);
115}
116
117/**
118 * list_del - deletes entry from list.
119 * @entry: the element to delete from the list.
120 * Note: list_empty() on entry does not return true after this, the entry is
121 * in an undefined state.
122 */
123static inline void list_del(struct list_head *entry)
124{
125	__list_del_entry(entry);
126	entry->next = LIST_POISON1;
127	entry->prev = LIST_POISON2;
128}
129
130/**
131 * list_is_head - tests whether @list is the list @head
132 * @list: the entry to test
133 * @head: the head of the list
134 */
135static inline int list_is_head(const struct list_head *list, const struct list_head *head)
136{
137	return list == head;
138}
139
140/**
141 * list_empty - tests whether a list is empty
142 * @head: the list to test.
143 */
144static inline int list_empty(const struct list_head *head)
145{
146	return head->next == head;
147}
148
149/**
150 * list_entry - get the struct for this entry
151 * @ptr:	the &struct list_head pointer.
152 * @type:	the type of the struct this is embedded in.
153 * @member:	the name of the list_head within the struct.
154 */
155#define list_entry(ptr, type, member) \
156	container_of(ptr, type, member)
157
158/**
159 * list_first_entry - get the first element from a list
160 * @ptr:	the list head to take the element from.
161 * @type:	the type of the struct this is embedded in.
162 * @member:	the name of the list_head within the struct.
163 *
164 * Note, that list is expected to be not empty.
165 */
166#define list_first_entry(ptr, type, member) \
167	list_entry((ptr)->next, type, member)
168
169/**
170 * list_next_entry - get the next element in list
171 * @pos:	the type * to cursor
172 * @member:	the name of the list_head within the struct.
173 */
174#define list_next_entry(pos, member) \
175	list_entry((pos)->member.next, typeof(*(pos)), member)
176
177/**
178 * list_entry_is_head - test if the entry points to the head of the list
179 * @pos:	the type * to cursor
180 * @head:	the head for your list.
181 * @member:	the name of the list_head within the struct.
182 */
183#define list_entry_is_head(pos, head, member)				\
184	(&pos->member == (head))
185
186/**
187 * list_for_each_entry - iterate over list of given type
188 * @pos:	the type * to use as a loop cursor.
189 * @head:	the head for your list.
190 * @member:	the name of the list_head within the struct.
191 */
192#define list_for_each_entry(pos, head, member)				\
193	for (pos = list_first_entry(head, typeof(*pos), member);	\
194	     !list_entry_is_head(pos, head, member);			\
195	     pos = list_next_entry(pos, member))
196
197/**
198 * list_for_each_entry_safe - iterate over list of given type. Safe against removal of list entry
199 * @pos:	the type * to use as a loop cursor.
200 * @n:		another type * to use as temporary storage
201 * @head:	the head for your list.
202 * @member:	the name of the list_head within the struct.
203 */
204#define list_for_each_entry_safe(pos, n, head, member)			\
205	for (pos = list_first_entry(head, typeof(*pos), member),	\
206		n = list_next_entry(pos, member);			\
207	     !list_entry_is_head(pos, head, member);			\
208	     pos = n, n = list_next_entry(n, member))
209
210/*
211 * Double linked lists with a single pointer list head.
212 * Mostly useful for hash tables where the two pointer list head is
213 * too wasteful.
214 * You lose the ability to access the tail in O(1).
215 */
216
217#define HLIST_HEAD_INIT { .first = NULL }
218
219/**
220 * hlist_add_head - add a new entry at the beginning of the hlist
221 * @n: new entry to be added
222 * @h: hlist head to add it after
223 *
224 * Insert a new entry after the specified head.
225 * This is good for implementing stacks.
226 */
227static inline void hlist_add_head(struct hlist_node *n, struct hlist_head *h)
228{
229	struct hlist_node *first = h->first;
230
231	n->next = first;
232	if (first)
233		first->pprev = &n->next;
234	h->first = n;
235	n->pprev = &h->first;
236}
237
238#define hlist_entry(ptr, type, member) container_of(ptr, type, member)
239
240#define hlist_entry_safe(ptr, type, member) \
241	({ typeof(ptr) ____ptr = (ptr); \
242	   ____ptr ? hlist_entry(____ptr, type, member) : NULL; \
243	})
244
245/**
246 * hlist_for_each_entry	- iterate over list of given type
247 * @pos:	the type * to use as a loop cursor.
248 * @head:	the head for your list.
249 * @member:	the name of the hlist_node within the struct.
250 */
251#define hlist_for_each_entry(pos, head, member)				\
252	for (pos = hlist_entry_safe((head)->first, typeof(*(pos)), member);\
253	     pos;							\
254	     pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member))
255
256#endif /* LIST_H */
257