btrfs-debug-tree: add -d option to print only the device mapping
[btrfs-progs-unstable.git] / list.h
blobd31090c1d0fc06579bdcebbc048192ed5d7bc21c
1 /*
2 * Copyright (C) 2007 Oracle. All rights reserved.
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public
6 * License v2 as published by the Free Software Foundation.
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11 * General Public License for more details.
13 * You should have received a copy of the GNU General Public
14 * License along with this program; if not, write to the
15 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
16 * Boston, MA 021110-1307, USA.
19 #ifndef _LINUX_LIST_H
20 #define _LINUX_LIST_H
22 #define LIST_POISON1 ((void *) 0x00100100)
23 #define LIST_POISON2 ((void *) 0x00200200)
26 * Simple doubly linked list implementation.
28 * Some of the internal functions ("__xxx") are useful when
29 * manipulating whole lists rather than single entries, as
30 * sometimes we already know the next/prev entries and we can
31 * generate better code by using them directly rather than
32 * using the generic single-entry routines.
35 struct list_head {
36 struct list_head *next, *prev;
39 #define LIST_HEAD_INIT(name) { &(name), &(name) }
41 #define LIST_HEAD(name) \
42 struct list_head name = LIST_HEAD_INIT(name)
44 static inline void INIT_LIST_HEAD(struct list_head *list)
46 list->next = list;
47 list->prev = list;
51 * Insert a new entry between two known consecutive entries.
53 * This is only for internal list manipulation where we know
54 * the prev/next entries already!
56 #ifndef CONFIG_DEBUG_LIST
57 static inline void __list_add(struct list_head *new,
58 struct list_head *prev,
59 struct list_head *next)
61 next->prev = new;
62 new->next = next;
63 new->prev = prev;
64 prev->next = new;
66 #else
67 extern void __list_add(struct list_head *new,
68 struct list_head *prev,
69 struct list_head *next);
70 #endif
72 /**
73 * list_add - add a new entry
74 * @new: new entry to be added
75 * @head: list head to add it after
77 * Insert a new entry after the specified head.
78 * This is good for implementing stacks.
80 #ifndef CONFIG_DEBUG_LIST
81 static inline void list_add(struct list_head *new, struct list_head *head)
83 __list_add(new, head, head->next);
85 #else
86 extern void list_add(struct list_head *new, struct list_head *head);
87 #endif
90 /**
91 * list_add_tail - add a new entry
92 * @new: new entry to be added
93 * @head: list head to add it before
95 * Insert a new entry before the specified head.
96 * This is useful for implementing queues.
98 static inline void list_add_tail(struct list_head *new, struct list_head *head)
100 __list_add(new, head->prev, head);
104 * Delete a list entry by making the prev/next entries
105 * point to each other.
107 * This is only for internal list manipulation where we know
108 * the prev/next entries already!
110 static inline void __list_del(struct list_head * prev, struct list_head * next)
112 next->prev = prev;
113 prev->next = next;
117 * list_del - deletes entry from list.
118 * @entry: the element to delete from the list.
119 * Note: list_empty on entry does not return true after this, the entry is
120 * in an undefined state.
122 #ifndef CONFIG_DEBUG_LIST
123 static inline void list_del(struct list_head *entry)
125 __list_del(entry->prev, entry->next);
126 entry->next = LIST_POISON1;
127 entry->prev = LIST_POISON2;
129 #else
130 extern void list_del(struct list_head *entry);
131 #endif
134 * list_replace - replace old entry by new one
135 * @old : the element to be replaced
136 * @new : the new element to insert
137 * Note: if 'old' was empty, it will be overwritten.
139 static inline void list_replace(struct list_head *old,
140 struct list_head *new)
142 new->next = old->next;
143 new->next->prev = new;
144 new->prev = old->prev;
145 new->prev->next = new;
148 static inline void list_replace_init(struct list_head *old,
149 struct list_head *new)
151 list_replace(old, new);
152 INIT_LIST_HEAD(old);
155 * list_del_init - deletes entry from list and reinitialize it.
156 * @entry: the element to delete from the list.
158 static inline void list_del_init(struct list_head *entry)
160 __list_del(entry->prev, entry->next);
161 INIT_LIST_HEAD(entry);
165 * list_move - delete from one list and add as another's head
166 * @list: the entry to move
167 * @head: the head that will precede our entry
169 static inline void list_move(struct list_head *list, struct list_head *head)
171 __list_del(list->prev, list->next);
172 list_add(list, head);
176 * list_move_tail - delete from one list and add as another's tail
177 * @list: the entry to move
178 * @head: the head that will follow our entry
180 static inline void list_move_tail(struct list_head *list,
181 struct list_head *head)
183 __list_del(list->prev, list->next);
184 list_add_tail(list, head);
188 * list_is_last - tests whether @list is the last entry in list @head
189 * @list: the entry to test
190 * @head: the head of the list
192 static inline int list_is_last(const struct list_head *list,
193 const struct list_head *head)
195 return list->next == head;
199 * list_empty - tests whether a list is empty
200 * @head: the list to test.
202 static inline int list_empty(const struct list_head *head)
204 return head->next == head;
208 * list_empty_careful - tests whether a list is empty and not being modified
209 * @head: the list to test
211 * Description:
212 * tests whether a list is empty _and_ checks that no other CPU might be
213 * in the process of modifying either member (next or prev)
215 * NOTE: using list_empty_careful() without synchronization
216 * can only be safe if the only activity that can happen
217 * to the list entry is list_del_init(). Eg. it cannot be used
218 * if another CPU could re-list_add() it.
220 static inline int list_empty_careful(const struct list_head *head)
222 struct list_head *next = head->next;
223 return (next == head) && (next == head->prev);
226 static inline void __list_splice(struct list_head *list,
227 struct list_head *head)
229 struct list_head *first = list->next;
230 struct list_head *last = list->prev;
231 struct list_head *at = head->next;
233 first->prev = head;
234 head->next = first;
236 last->next = at;
237 at->prev = last;
241 * list_splice - join two lists
242 * @list: the new list to add.
243 * @head: the place to add it in the first list.
245 static inline void list_splice(struct list_head *list, struct list_head *head)
247 if (!list_empty(list))
248 __list_splice(list, head);
252 * list_splice_init - join two lists and reinitialise the emptied list.
253 * @list: the new list to add.
254 * @head: the place to add it in the first list.
256 * The list at @list is reinitialised
258 static inline void list_splice_init(struct list_head *list,
259 struct list_head *head)
261 if (!list_empty(list)) {
262 __list_splice(list, head);
263 INIT_LIST_HEAD(list);
268 * list_entry - get the struct for this entry
269 * @ptr: the &struct list_head pointer.
270 * @type: the type of the struct this is embedded in.
271 * @member: the name of the list_struct within the struct.
273 #define list_entry(ptr, type, member) \
274 container_of(ptr, type, member)
277 * list_for_each - iterate over a list
278 * @pos: the &struct list_head to use as a loop cursor.
279 * @head: the head for your list.
281 #define list_for_each(pos, head) \
282 for (pos = (head)->next; pos != (head); \
283 pos = pos->next)
286 * __list_for_each - iterate over a list
287 * @pos: the &struct list_head to use as a loop cursor.
288 * @head: the head for your list.
290 * This variant differs from list_for_each() in that it's the
291 * simplest possible list iteration code, no prefetching is done.
292 * Use this for code that knows the list to be very short (empty
293 * or 1 entry) most of the time.
295 #define __list_for_each(pos, head) \
296 for (pos = (head)->next; pos != (head); pos = pos->next)
299 * list_for_each_prev - iterate over a list backwards
300 * @pos: the &struct list_head to use as a loop cursor.
301 * @head: the head for your list.
303 #define list_for_each_prev(pos, head) \
304 for (pos = (head)->prev; pos != (head); \
305 pos = pos->prev)
308 * list_for_each_safe - iterate over a list safe against removal of list entry
309 * @pos: the &struct list_head to use as a loop cursor.
310 * @n: another &struct list_head to use as temporary storage
311 * @head: the head for your list.
313 #define list_for_each_safe(pos, n, head) \
314 for (pos = (head)->next, n = pos->next; pos != (head); \
315 pos = n, n = pos->next)
318 * list_for_each_entry - iterate over list of given type
319 * @pos: the type * to use as a loop cursor.
320 * @head: the head for your list.
321 * @member: the name of the list_struct within the struct.
323 #define list_for_each_entry(pos, head, member) \
324 for (pos = list_entry((head)->next, typeof(*pos), member); \
325 &pos->member != (head); \
326 pos = list_entry(pos->member.next, typeof(*pos), member))
329 * list_for_each_entry_reverse - iterate backwards over list of given type.
330 * @pos: the type * to use as a loop cursor.
331 * @head: the head for your list.
332 * @member: the name of the list_struct within the struct.
334 #define list_for_each_entry_reverse(pos, head, member) \
335 for (pos = list_entry((head)->prev, typeof(*pos), member); \
336 &pos->member != (head); \
337 pos = list_entry(pos->member.prev, typeof(*pos), member))
340 * list_prepare_entry - prepare a pos entry for use in list_for_each_entry_continue
341 * @pos: the type * to use as a start point
342 * @head: the head of the list
343 * @member: the name of the list_struct within the struct.
345 * Prepares a pos entry for use as a start point in list_for_each_entry_continue.
347 #define list_prepare_entry(pos, head, member) \
348 ((pos) ? : list_entry(head, typeof(*pos), member))
351 * list_for_each_entry_continue - continue iteration over list of given type
352 * @pos: the type * to use as a loop cursor.
353 * @head: the head for your list.
354 * @member: the name of the list_struct within the struct.
356 * Continue to iterate over list of given type, continuing after
357 * the current position.
359 #define list_for_each_entry_continue(pos, head, member) \
360 for (pos = list_entry(pos->member.next, typeof(*pos), member); \
361 &pos->member != (head); \
362 pos = list_entry(pos->member.next, typeof(*pos), member))
365 * list_for_each_entry_from - iterate over list of given type from the current point
366 * @pos: the type * to use as a loop cursor.
367 * @head: the head for your list.
368 * @member: the name of the list_struct within the struct.
370 * Iterate over list of given type, continuing from current position.
372 #define list_for_each_entry_from(pos, head, member) \
373 for (; &pos->member != (head); \
374 pos = list_entry(pos->member.next, typeof(*pos), member))
377 * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry
378 * @pos: the type * to use as a loop cursor.
379 * @n: another type * to use as temporary storage
380 * @head: the head for your list.
381 * @member: the name of the list_struct within the struct.
383 #define list_for_each_entry_safe(pos, n, head, member) \
384 for (pos = list_entry((head)->next, typeof(*pos), member), \
385 n = list_entry(pos->member.next, typeof(*pos), member); \
386 &pos->member != (head); \
387 pos = n, n = list_entry(n->member.next, typeof(*n), member))
390 * list_for_each_entry_safe_continue
391 * @pos: the type * to use as a loop cursor.
392 * @n: another type * to use as temporary storage
393 * @head: the head for your list.
394 * @member: the name of the list_struct within the struct.
396 * Iterate over list of given type, continuing after current point,
397 * safe against removal of list entry.
399 #define list_for_each_entry_safe_continue(pos, n, head, member) \
400 for (pos = list_entry(pos->member.next, typeof(*pos), member), \
401 n = list_entry(pos->member.next, typeof(*pos), member); \
402 &pos->member != (head); \
403 pos = n, n = list_entry(n->member.next, typeof(*n), member))
406 * list_for_each_entry_safe_from
407 * @pos: the type * to use as a loop cursor.
408 * @n: another type * to use as temporary storage
409 * @head: the head for your list.
410 * @member: the name of the list_struct within the struct.
412 * Iterate over list of given type from current point, safe against
413 * removal of list entry.
415 #define list_for_each_entry_safe_from(pos, n, head, member) \
416 for (n = list_entry(pos->member.next, typeof(*pos), member); \
417 &pos->member != (head); \
418 pos = n, n = list_entry(n->member.next, typeof(*n), member))
421 * list_for_each_entry_safe_reverse
422 * @pos: the type * to use as a loop cursor.
423 * @n: another type * to use as temporary storage
424 * @head: the head for your list.
425 * @member: the name of the list_struct within the struct.
427 * Iterate backwards over list of given type, safe against removal
428 * of list entry.
430 #define list_for_each_entry_safe_reverse(pos, n, head, member) \
431 for (pos = list_entry((head)->prev, typeof(*pos), member), \
432 n = list_entry(pos->member.prev, typeof(*pos), member); \
433 &pos->member != (head); \
434 pos = n, n = list_entry(n->member.prev, typeof(*n), member))
436 #endif