2 * Copied from the Linux kernel source tree, version 2.6.13.
4 * Licensed under the GPL v2 as per the whole kernel source tree.
7 /** \file list.h Doubly linked list implementation. */
9 #include <stddef.h> /* offsetof */
11 /** Get the struct this entry is embedded in. */
12 #define container_of(ptr, type, member) ({ \
13 const typeof( ((type *)0)->member ) *__mptr = (ptr); \
14 (type *)( (char *)__mptr - offsetof(type,member) );})
16 /** A list head is just a pair of pointers. */
18 /** Pointer to the next list entry. */
19 struct list_head *next;
20 /** Pointer to the previous list entry. */
21 struct list_head *prev;
24 /** Define an initialized list head. */
25 #define INITIALIZED_LIST_HEAD(name) struct list_head name = {&(name), &(name)}
27 /** This must be called before using any other list functions. */
28 #define INIT_LIST_HEAD(ptr) do { \
29 (ptr)->next = (ptr); (ptr)->prev = (ptr); \
33 * Insert a new entry after the specified head.
35 * \param entry The new entry to add.
36 * \param head The list head to add it after.
38 * This is good for implementing stacks.
40 static inline void para_list_add(struct list_head *entry, struct list_head *head)
43 entry->next = head->next;
44 head->next->prev = entry;
49 * Insert a new entry before the specified head.
51 * \param entry The new entry to add.
52 * \param head list head to add it before.
54 * This is useful for implementing queues.
56 static inline void list_add_tail(struct list_head *entry, struct list_head *head)
58 entry->prev = head->prev;
60 head->prev->next = entry;
65 * Delete an entry from a list.
67 * \param entry The element to delete.
69 * The list entry is in an undefined state after this and \ref list_empty()
70 * does not return true.
72 static inline void list_del(struct list_head *entry)
74 entry->prev->next = entry->next;
75 entry->next->prev = entry->prev;
77 * These non-NULL pointers result in page faults when dereferenced.
78 * This helps to catch bugs resulting from using deleted list heads.
80 entry->next = (void *)0x00100100;
81 entry->prev = (void *)0x00200200;
85 * Delete an entry from one list and add it as another list's head.
87 * \param entry The entry to move.
88 * \param head The head that will precede our entry.
90 static inline void list_move(struct list_head *entry, struct list_head *head)
93 para_list_add(entry, head);
97 * Test whether a list contains no entries.
99 * \param head The list to test.
101 static inline int list_empty(const struct list_head *head)
103 return head->next == head;
107 * Test whether a list has just one entry.
109 * \param head The list to test.
111 static inline int list_is_singular(const struct list_head *head)
113 return !list_empty(head) && (head->next == head->prev);
117 * Get the struct in which this entry is embedded in.
119 * \param ptr The list head pointer.
120 * \param type The type of containing structure.
121 * \param member The name of the list head member within the structure.
123 #define list_entry(ptr, type, member) container_of(ptr, type, member)
126 * Iterate over a list.
128 * \param pos A struct pointer which serves as the iterator.
129 * \param head The head of the list.
130 * \param member The name of the list head member within the structure.
132 #define list_for_each_entry(pos, head, member) \
133 for (pos = list_entry((head)->next, typeof(*pos), member); \
134 &pos->member != (head); \
135 pos = list_entry(pos->member.next, typeof(*pos), member))
138 * Iterate over list, safe against removal of list entry.
140 * \param pos The iterator struct pointer.
141 * \param n A second struct pointer which is used as temporary storage.
142 * \param head The head of the list.
143 * \param member The name of the list head member within the structure.
145 #define list_for_each_entry_safe(pos, n, head, member) \
146 for (pos = list_entry((head)->next, typeof(*pos), member), \
147 n = list_entry(pos->member.next, typeof(*pos), member); \
148 &pos->member != (head); \
149 pos = n, n = list_entry(n->member.next, typeof(*n), member))
152 * Get the first element of a list.
154 * \param ptr The list head to take the element from.
155 * \param type The type of the struct this is embedded in.
156 * \param member The name of the list_struct within the struct.
158 * Note that the list is expected to be non-empty.
160 #define list_first_entry(ptr, type, member) \
161 list_entry((ptr)->next, type, member)