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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_replace - replace old entry by new one
132 * @old : the element to be replaced
133 * @new : the new element to insert
134 *
135 * If @old was empty, it will be overwritten.
136 */
137static inline void list_replace(struct list_head *old,
138 struct list_head *new)
139{
140 new->next = old->next;
141 new->next->prev = new;
142 new->prev = old->prev;
143 new->prev->next = new;
144}
145
146/**
147 * list_replace_init - replace old entry by new one and initialize the old one
148 * @old : the element to be replaced
149 * @new : the new element to insert
150 *
151 * If @old was empty, it will be overwritten.
152 */
153static inline void list_replace_init(struct list_head *old,
154 struct list_head *new)
155{
156 list_replace(old, new);
157 INIT_LIST_HEAD(old);
158}
159
160/**
161 * list_move - delete from one list and add as another's head
162 * @list: the entry to move
163 * @head: the head that will precede our entry
164 */
165static inline void list_move(struct list_head *list, struct list_head *head)
166{
167 __list_del_entry(list);
168 list_add(list, head);
169}
170
171/**
172 * list_move_tail - delete from one list and add as another's tail
173 * @list: the entry to move
174 * @head: the head that will follow our entry
175 */
176static inline void list_move_tail(struct list_head *list,
177 struct list_head *head)
178{
179 __list_del_entry(list);
180 list_add_tail(list, head);
181}
182
183/**
184 * list_is_first -- tests whether @list is the first entry in list @head
185 * @list: the entry to test
186 * @head: the head of the list
187 */
188static inline int list_is_first(const struct list_head *list, const struct list_head *head)
189{
190 return list->prev == head;
191}
192
193/**
194 * list_is_last - tests whether @list is the last entry in list @head
195 * @list: the entry to test
196 * @head: the head of the list
197 */
198static inline int list_is_last(const struct list_head *list, const struct list_head *head)
199{
200 return list->next == head;
201}
202
203/**
204 * list_is_head - tests whether @list is the list @head
205 * @list: the entry to test
206 * @head: the head of the list
207 */
208static inline int list_is_head(const struct list_head *list, const struct list_head *head)
209{
210 return list == head;
211}
212
213/**
214 * list_empty - tests whether a list is empty
215 * @head: the list to test.
216 */
217static inline int list_empty(const struct list_head *head)
218{
219 return head->next == head;
220}
221
222/**
223 * list_entry - get the struct for this entry
224 * @ptr: the &struct list_head pointer.
225 * @type: the type of the struct this is embedded in.
226 * @member: the name of the list_head within the struct.
227 */
228#define list_entry(ptr, type, member) \
229 container_of(ptr, type, member)
230
231/**
232 * list_first_entry - get the first element from a list
233 * @ptr: the list head to take the element from.
234 * @type: the type of the struct this is embedded in.
235 * @member: the name of the list_head within the struct.
236 *
237 * Note, that list is expected to be not empty.
238 */
239#define list_first_entry(ptr, type, member) \
240 list_entry((ptr)->next, type, member)
241
242/**
243 * list_last_entry - get the last element from a list
244 * @ptr: the list head to take the element from.
245 * @type: the type of the struct this is embedded in.
246 * @member: the name of the list_head within the struct.
247 *
248 * Note, that list is expected to be not empty.
249 */
250#define list_last_entry(ptr, type, member) \
251 list_entry((ptr)->prev, type, member)
252
253/**
254 * list_next_entry - get the next element in list
255 * @pos: the type * to cursor
256 * @member: the name of the list_head within the struct.
257 */
258#define list_next_entry(pos, member) \
259 list_entry((pos)->member.next, typeof(*(pos)), member)
260
261/**
262 * list_prev_entry - get the prev element in list
263 * @pos: the type * to cursor
264 * @member: the name of the list_head within the struct.
265 */
266#define list_prev_entry(pos, member) \
267 list_entry((pos)->member.prev, typeof(*(pos)), member)
268
269/**
270 * list_entry_is_head - test if the entry points to the head of the list
271 * @pos: the type * to cursor
272 * @head: the head for your list.
273 * @member: the name of the list_head within the struct.
274 */
275#define list_entry_is_head(pos, head, member) \
276 (&pos->member == (head))
277
278/**
279 * list_for_each_entry - iterate over list of given type
280 * @pos: the type * to use as a loop cursor.
281 * @head: the head for your list.
282 * @member: the name of the list_head within the struct.
283 */
284#define list_for_each_entry(pos, head, member) \
285 for (pos = list_first_entry(head, typeof(*pos), member); \
286 !list_entry_is_head(pos, head, member); \
287 pos = list_next_entry(pos, member))
288
289/**
290 * list_for_each_entry_reverse - iterate backwards over list of given type.
291 * @pos: the type * to use as a loop cursor.
292 * @head: the head for your list.
293 * @member: the name of the list_head within the struct.
294 */
295#define list_for_each_entry_reverse(pos, head, member) \
296 for (pos = list_last_entry(head, typeof(*pos), member); \
297 !list_entry_is_head(pos, head, member); \
298 pos = list_prev_entry(pos, member))
299
300/**
301 * list_for_each_entry_safe - iterate over list of given type. Safe against removal of list entry
302 * @pos: the type * to use as a loop cursor.
303 * @n: another type * to use as temporary storage
304 * @head: the head for your list.
305 * @member: the name of the list_head within the struct.
306 */
307#define list_for_each_entry_safe(pos, n, head, member) \
308 for (pos = list_first_entry(head, typeof(*pos), member), \
309 n = list_next_entry(pos, member); \
310 !list_entry_is_head(pos, head, member); \
311 pos = n, n = list_next_entry(n, member))
312
313/*
314 * Double linked lists with a single pointer list head.
315 * Mostly useful for hash tables where the two pointer list head is
316 * too wasteful.
317 * You lose the ability to access the tail in O(1).
318 */
319
320#define HLIST_HEAD_INIT { .first = NULL }
321#define INIT_HLIST_HEAD(ptr) ((ptr)->first = NULL)
322static inline void INIT_HLIST_NODE(struct hlist_node *h)
323{
324 h->next = NULL;
325 h->pprev = NULL;
326}
327
328/**
329 * hlist_unhashed - Has node been removed from list and reinitialized?
330 * @h: Node to be checked
331 *
332 * Not that not all removal functions will leave a node in unhashed
333 * state. For example, hlist_nulls_del_init_rcu() does leave the
334 * node in unhashed state, but hlist_nulls_del() does not.
335 */
336static inline int hlist_unhashed(const struct hlist_node *h)
337{
338 return !h->pprev;
339}
340
341static inline void __hlist_del(struct hlist_node *n)
342{
343 struct hlist_node *next = n->next;
344 struct hlist_node **pprev = n->pprev;
345
346 *pprev = next;
347 if (next)
348 next->pprev = pprev;
349}
350
351/**
352 * hlist_del - Delete the specified hlist_node from its list
353 * @n: Node to delete.
354 *
355 * Note that this function leaves the node in hashed state. Use
356 * hlist_del_init() or similar instead to unhash @n.
357 */
358static inline void hlist_del(struct hlist_node *n)
359{
360 __hlist_del(n);
361 n->next = LIST_POISON1;
362 n->pprev = LIST_POISON2;
363}
364
365/**
366 * hlist_del_init - Delete the specified hlist_node from its list and initialize
367 * @n: Node to delete.
368 *
369 * Note that this function leaves the node in unhashed state.
370 */
371static inline void hlist_del_init(struct hlist_node *n)
372{
373 if (!hlist_unhashed(n)) {
374 __hlist_del(n);
375 INIT_HLIST_NODE(n);
376 }
377}
378
379/**
380 * hlist_add_head - add a new entry at the beginning of the hlist
381 * @n: new entry to be added
382 * @h: hlist head to add it after
383 *
384 * Insert a new entry after the specified head.
385 * This is good for implementing stacks.
386 */
387static inline void hlist_add_head(struct hlist_node *n, struct hlist_head *h)
388{
389 struct hlist_node *first = h->first;
390
391 n->next = first;
392 if (first)
393 first->pprev = &n->next;
394 h->first = n;
395 n->pprev = &h->first;
396}
397
398#define hlist_entry(ptr, type, member) container_of(ptr, type, member)
399
400#define hlist_entry_safe(ptr, type, member) \
401 ({ typeof(ptr) ____ptr = (ptr); \
402 ____ptr ? hlist_entry(____ptr, type, member) : NULL; \
403 })
404
405/**
406 * hlist_for_each_entry - iterate over list of given type
407 * @pos: the type * to use as a loop cursor.
408 * @head: the head for your list.
409 * @member: the name of the hlist_node within the struct.
410 */
411#define hlist_for_each_entry(pos, head, member) \
412 for (pos = hlist_entry_safe((head)->first, typeof(*(pos)), member);\
413 pos; \
414 pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member))
415
416/**
417 * hlist_for_each_entry_safe - iterate over list of given type safe against removal of list entry
418 * @pos: the type * to use as a loop cursor.
419 * @n: a &struct hlist_node to use as temporary storage
420 * @head: the head for your list.
421 * @member: the name of the hlist_node within the struct.
422 */
423#define hlist_for_each_entry_safe(pos, n, head, member) \
424 for (pos = hlist_entry_safe((head)->first, typeof(*pos), member);\
425 pos && ({ n = pos->member.next; 1; }); \
426 pos = hlist_entry_safe(n, typeof(*pos), member))
427
428#endif /* LIST_H */