xref: /openbmc/linux/scripts/mod/list.h (revision 9a29f5fc)
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, head, 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, head->prev, 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(entry->prev, 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