209d8701c9c6a975972ed3a6a98c557f3554ddd8
[paraslash.git] / list.h
1 /*
2 * Copied from the Linux kernel source tree, version 2.6.13.
3 *
4 * Licensed under the GPL v2 as per the whole kernel source tree.
5 *
6 */
7
8 #include <stddef.h> /* offsetof */
9
10 #define container_of(ptr, type, member) ({ \
11 const typeof( ((type *)0)->member ) *__mptr = (ptr); \
12 (type *)( (char *)__mptr - offsetof(type,member) );})
13
14 /*
15 * These are non-NULL pointers that will result in page faults
16 * under normal circumstances, used to verify that nobody uses
17 * non-initialized list entries.
18 */
19 #define LIST_POISON1 ((void *) 0x00100100)
20 #define LIST_POISON2 ((void *) 0x00200200)
21
22 /**
23 * Simple doubly linked list implementation.
24 *
25 * Some of the internal functions ("__xxx") are useful when
26 * manipulating whole lists rather than single entries, as
27 * sometimes we already know the next/prev entries and we can
28 * generate better code by using them directly rather than
29 * using the generic single-entry routines.
30 */
31 struct list_head {
32 struct list_head *next, *prev;
33 };
34
35 #define INIT_LIST_HEAD(ptr) do { \
36 (ptr)->next = (ptr); (ptr)->prev = (ptr); \
37 } while (0)
38
39 /*
40 * Insert a new entry between two known consecutive entries.
41 *
42 * This is only for internal list manipulation where we know
43 * the prev/next entries already!
44 */
45 static inline void __list_add(struct list_head *new,
46 struct list_head *prev,
47 struct list_head *next)
48 {
49 next->prev = new;
50 new->next = next;
51 new->prev = prev;
52 prev->next = new;
53 }
54
55 /**
56 * add a new entry
57 *
58 * \param new new entry to be added
59 * \param head list head to add it after
60 *
61 * Insert a new entry after the specified head.
62 * This is good for implementing stacks.
63 */
64 static inline void para_list_add(struct list_head *new, struct list_head *head)
65 {
66 __list_add(new, head, head->next);
67 }
68
69 /**
70 * add a new entry
71 *
72 * \param new new entry to be added
73 * \param head list head to add it before
74 *
75 * Insert a new entry before the specified head.
76 * This is useful for implementing queues.
77 */
78 static inline void list_add_tail(struct list_head *new, struct list_head *head)
79 {
80 __list_add(new, head->prev, head);
81 }
82
83 /*
84 * Delete a list entry by making the prev/next entries
85 * point to each other.
86 *
87 * This is only for internal list manipulation where we know
88 * the prev/next entries already!
89 */
90 static inline void __list_del(struct list_head * prev, struct list_head * next)
91 {
92 next->prev = prev;
93 prev->next = next;
94 }
95
96 /**
97 * Delete entry from list.
98 *
99 * \param entry the element to delete from the list.
100 *
101 * Note: list_empty on entry does not return true after this, the entry is
102 * in an undefined state.
103 */
104 static inline void list_del(struct list_head *entry)
105 {
106 __list_del(entry->prev, entry->next);
107 entry->next = LIST_POISON1;
108 entry->prev = LIST_POISON2;
109 }
110
111 /**
112 * delete from one list and add as another's head
113 *
114 * \param list: the entry to move
115 * \param head: the head that will precede our entry
116 */
117 static inline void list_move(struct list_head *list, struct list_head *head)
118 {
119 __list_del(list->prev, list->next);
120 para_list_add(list, head);
121 }
122
123 /**
124 * test whether a list is empty
125 *
126 * \param head the list to test.
127 */
128 static inline int list_empty(const struct list_head *head)
129 {
130 return head->next == head;
131 }
132
133 /**
134 * get the struct for this entry
135 *
136 * \param ptr the &struct list_head pointer.
137 * \param type the type of the struct this is embedded in.
138 * \param member the name of the list_struct within the struct.
139 */
140 #define list_entry(ptr, type, member) \
141 container_of(ptr, type, member)
142
143 /**
144 * iterate over a list safe against removal of list entry
145 *
146 * \param pos the &struct list_head to use as a loop counter.
147 * \param n another &struct list_head to use as temporary storage
148 * \param head the head for your list.
149 */
150 #define list_for_each_safe(pos, n, head) \
151 for (pos = (head)->next, n = pos->next; pos != (head); \
152 pos = n, n = pos->next)
153
154 /**
155 * iterate over list of given type
156 *
157 * \param pos the type * to use as a loop counter.
158 * \param head the head for your list.
159 * \param member the name of the list_struct within the struct.
160 */
161 #define list_for_each_entry(pos, head, member) \
162 for (pos = list_entry((head)->next, typeof(*pos), member); \
163 &pos->member != (head); \
164 pos = list_entry(pos->member.next, typeof(*pos), member))
165
166 /**
167 * iterate over list of given type safe against removal of list entry
168 *
169 * \param pos the type * to use as a loop counter.
170 * \param n another type * to use as temporary storage
171 * \param head the head for your list.
172 * \param member the name of the list_struct within the struct.
173 */
174 #define list_for_each_entry_safe(pos, n, head, member) \
175 for (pos = list_entry((head)->next, typeof(*pos), member), \
176 n = list_entry(pos->member.next, typeof(*pos), member); \
177 &pos->member != (head); \
178 pos = n, n = list_entry(n->member.next, typeof(*n), member))
179 /**
180 * iterate backwards over list of given type safe against removal of list entry
181 * \param pos the type * to use as a loop counter.
182 * \param n another type * to use as temporary storage
183 * \param head the head for your list.
184 * \param member the name of the list_struct within the struct.
185 */
186 #define list_for_each_entry_safe_reverse(pos, n, head, member) \
187 for (pos = list_entry((head)->prev, typeof(*pos), member), \
188 n = list_entry(pos->member.prev, typeof(*pos), member); \
189 &pos->member != (head); \
190 pos = n, n = list_entry(n->member.prev, typeof(*n), member))