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