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Linux/include/linux/list.h

  1 #ifndef _LINUX_LIST_H
  2 #define _LINUX_LIST_H
  3 
  4 #if defined(__KERNEL__) || defined(_LVM_H_INCLUDE)
  5 
  6 #include <linux/prefetch.h>
  7 
  8 /*
  9  * Simple doubly linked list implementation.
 10  *
 11  * Some of the internal functions ("__xxx") are useful when
 12  * manipulating whole lists rather than single entries, as
 13  * sometimes we already know the next/prev entries and we can
 14  * generate better code by using them directly rather than
 15  * using the generic single-entry routines.
 16  */
 17 
 18 struct list_head {
 19         struct list_head *next, *prev;
 20 };
 21 
 22 #define LIST_HEAD_INIT(name) { &(name), &(name) }
 23 
 24 #define LIST_HEAD(name) \
 25         struct list_head name = LIST_HEAD_INIT(name)
 26 
 27 #define INIT_LIST_HEAD(ptr) do { \
 28         (ptr)->next = (ptr); (ptr)->prev = (ptr); \
 29 } while (0)
 30 
 31 /*
 32  * Insert a new entry between two known consecutive entries. 
 33  *
 34  * This is only for internal list manipulation where we know
 35  * the prev/next entries already!
 36  */
 37 static inline void __list_add(struct list_head *new,
 38                               struct list_head *prev,
 39                               struct list_head *next)
 40 {
 41         next->prev = new;
 42         new->next = next;
 43         new->prev = prev;
 44         prev->next = new;
 45 }
 46 
 47 /**
 48  * list_add - add a new entry
 49  * @new: new entry to be added
 50  * @head: list head to add it after
 51  *
 52  * Insert a new entry after the specified head.
 53  * This is good for implementing stacks.
 54  */
 55 static inline void list_add(struct list_head *new, struct list_head *head)
 56 {
 57         __list_add(new, head, head->next);
 58 }
 59 
 60 /**
 61  * list_add_tail - add a new entry
 62  * @new: new entry to be added
 63  * @head: list head to add it before
 64  *
 65  * Insert a new entry before the specified head.
 66  * This is useful for implementing queues.
 67  */
 68 static inline void list_add_tail(struct list_head *new, struct list_head *head)
 69 {
 70         __list_add(new, head->prev, head);
 71 }
 72 
 73 /*
 74  * Delete a list entry by making the prev/next entries
 75  * point to each other.
 76  *
 77  * This is only for internal list manipulation where we know
 78  * the prev/next entries already!
 79  */
 80 static inline void __list_del(struct list_head *prev, struct list_head *next)
 81 {
 82         next->prev = prev;
 83         prev->next = next;
 84 }
 85 
 86 /**
 87  * list_del - deletes entry from list.
 88  * @entry: the element to delete from the list.
 89  * Note: list_empty on entry does not return true after this, the entry is in an undefined state.
 90  */
 91 static inline void list_del(struct list_head *entry)
 92 {
 93         __list_del(entry->prev, entry->next);
 94         entry->next = (void *) 0;
 95         entry->prev = (void *) 0;
 96 }
 97 
 98 /**
 99  * list_del_init - deletes entry from list and reinitialize it.
100  * @entry: the element to delete from the list.
101  */
102 static inline void list_del_init(struct list_head *entry)
103 {
104         __list_del(entry->prev, entry->next);
105         INIT_LIST_HEAD(entry); 
106 }
107 
108 /**
109  * list_move - delete from one list and add as another's head
110  * @list: the entry to move
111  * @head: the head that will precede our entry
112  */
113 static inline void list_move(struct list_head *list, struct list_head *head)
114 {
115         __list_del(list->prev, list->next);
116         list_add(list, head);
117 }
118 
119 /**
120  * list_move_tail - delete from one list and add as another's tail
121  * @list: the entry to move
122  * @head: the head that will follow our entry
123  */
124 static inline void list_move_tail(struct list_head *list,
125                                   struct list_head *head)
126 {
127         __list_del(list->prev, list->next);
128         list_add_tail(list, head);
129 }
130 
131 /**
132  * list_empty - tests whether a list is empty
133  * @head: the list to test.
134  */
135 static inline int list_empty(struct list_head *head)
136 {
137         return head->next == head;
138 }
139 
140 static inline void __list_splice(struct list_head *list,
141                                  struct list_head *head)
142 {
143         struct list_head *first = list->next;
144         struct list_head *last = list->prev;
145         struct list_head *at = head->next;
146 
147         first->prev = head;
148         head->next = first;
149 
150         last->next = at;
151         at->prev = last;
152 }
153 
154 /**
155  * list_splice - join two lists
156  * @list: the new list to add.
157  * @head: the place to add it in the first list.
158  */
159 static inline void list_splice(struct list_head *list, struct list_head *head)
160 {
161         if (!list_empty(list))
162                 __list_splice(list, head);
163 }
164 
165 /**
166  * list_splice_init - join two lists and reinitialise the emptied list.
167  * @list: the new list to add.
168  * @head: the place to add it in the first list.
169  *
170  * The list at @list is reinitialised
171  */
172 static inline void list_splice_init(struct list_head *list,
173                                     struct list_head *head)
174 {
175         if (!list_empty(list)) {
176                 __list_splice(list, head);
177                 INIT_LIST_HEAD(list);
178         }
179 }
180 
181 /**
182  * list_entry - get the struct for this entry
183  * @ptr:        the &struct list_head pointer.
184  * @type:       the type of the struct this is embedded in.
185  * @member:     the name of the list_struct within the struct.
186  */
187 #define list_entry(ptr, type, member) \
188         ((type *)((char *)(ptr)-(unsigned long)(&((type *)0)->member)))
189 
190 /**
191  * list_for_each        -       iterate over a list
192  * @pos:        the &struct list_head to use as a loop counter.
193  * @head:       the head for your list.
194  */
195 #define list_for_each(pos, head) \
196         for (pos = (head)->next, prefetch(pos->next); pos != (head); \
197                 pos = pos->next, prefetch(pos->next))
198 /**
199  * list_for_each_prev   -       iterate over a list backwards
200  * @pos:        the &struct list_head to use as a loop counter.
201  * @head:       the head for your list.
202  */
203 #define list_for_each_prev(pos, head) \
204         for (pos = (head)->prev, prefetch(pos->prev); pos != (head); \
205                 pos = pos->prev, prefetch(pos->prev))
206                 
207 /**
208  * list_for_each_safe   -       iterate over a list safe against removal of list entry
209  * @pos:        the &struct list_head to use as a loop counter.
210  * @n:          another &struct list_head to use as temporary storage
211  * @head:       the head for your list.
212  */
213 #define list_for_each_safe(pos, n, head) \
214         for (pos = (head)->next, n = pos->next; pos != (head); \
215                 pos = n, n = pos->next)
216 
217 /**
218  * list_for_each_entry  -       iterate over list of given type
219  * @pos:        the type * to use as a loop counter.
220  * @head:       the head for your list.
221  * @member:     the name of the list_struct within the struct.
222  */
223 #define list_for_each_entry(pos, head, member)                          \
224         for (pos = list_entry((head)->next, typeof(*pos), member),      \
225                      prefetch(pos->member.next);                        \
226              &pos->member != (head);                                    \
227              pos = list_entry(pos->member.next, typeof(*pos), member),  \
228                      prefetch(pos->member.next))
229 
230 /**
231  * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry
232  * @pos:        the type * to use as a loop counter.
233  * @n:          another type * to use as temporary storage
234  * @head:       the head for your list.
235  * @member:     the name of the list_struct within the struct.
236  */
237 #define list_for_each_entry_safe(pos, n, head, member)                  \
238         for (pos = list_entry((head)->next, typeof(*pos), member),      \
239                 n = list_entry(pos->member.next, typeof(*pos), member); \
240              &pos->member != (head);                                    \
241              pos = n, n = list_entry(n->member.next, typeof(*n), member))
242 
243 /**
244  * list_for_each_entry_continue -       iterate over list of given type
245  *                      continuing after existing point
246  * @pos:        the type * to use as a loop counter.
247  * @head:       the head for your list.
248  * @member:     the name of the list_struct within the struct.
249  */
250 #define list_for_each_entry_continue(pos, head, member)                 \
251         for (pos = list_entry(pos->member.next, typeof(*pos), member),  \
252                      prefetch(pos->member.next);                        \
253              &pos->member != (head);                                    \
254              pos = list_entry(pos->member.next, typeof(*pos), member),  \
255                      prefetch(pos->member.next))
256 
257 #endif /* __KERNEL__ || _LVM_H_INCLUDE */
258 
259 #endif
260 

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