Commit 00e8a4da authored by Luis R. Rodriguez's avatar Luis R. Rodriguez Committed by John W. Linville
Browse files

list.h: add list_cut_position() 



This adds list_cut_position() which lets you cut a list into
two lists given a pivot in the list.

Signed-off-by: default avatarLuis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: default avatarJohn W. Linville <linville@tuxdriver.com>
parent 7d283aee

include/linux/list.h

+40 −0
Original line number Diff line number Diff line
@@ -214,6 +214,46 @@ static inline int list_is_singular(const struct list_head *head) 
	return !list_empty(head) && (head->next == head->prev);

}



static inline void __list_cut_position(struct list_head *list,

		struct list_head *head, struct list_head *entry)

{

	struct list_head *new_first = entry->next;

	list->next = head->next;

	list->next->prev = list;

	list->prev = entry;

	entry->next = list;

	head->next = new_first;

	new_first->prev = head;

}



/**

 * list_cut_position - cut a list into two

 * @list: a new list to add all removed entries

 * @head: a list with entries

 * @entry: an entry within head, could be the head itself

 *	and if so we won't cut the list

 *

 * This helper moves the initial part of @head, up to and

 * including @entry, from @head to @list. You should

 * pass on @entry an element you know is on @head. @list

 * should be an empty list or a list you do not care about

 * losing its data.

 *

 */

static inline void list_cut_position(struct list_head *list,

		struct list_head *head, struct list_head *entry)

{

	if (list_empty(head))

		return;

	if (list_is_singular(head) &&

		(head->next != entry && head != entry))

		return;

	if (entry == head)

		INIT_LIST_HEAD(list);

	else

		__list_cut_position(list, head, entry);

}



static inline void __list_splice(const struct list_head *list,

				 struct list_head *prev,

				 struct list_head *next)