From 58e642093b18f10064f91a50b2a325e39cbb0e13 Mon Sep 17 00:00:00 2001 From: Luis R. Rodriguez Date: Sun, 3 Aug 2008 23:13:11 -0700 Subject: [PATCH 2/4] list.h: add list_cut_position() To: linville@tuxdriver.com Cc: linux-wireless@vger.kernel.org, ath9k-devel@lists.ath9k.org This adds list_cut_position() which lets you cut a list into two lists given a pivot in the list. Signed-off-by: Luis R. Rodriguez --- include/linux/list.h | 32 ++++++++++++++++++++++++++++++++ 1 files changed, 32 insertions(+), 0 deletions(-) diff --git a/include/linux/list.h b/include/linux/list.h index 594f67c..2999b0f 100644 --- a/include/linux/list.h +++ b/include/linux/list.h @@ -214,6 +214,38 @@ 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 != head) ? entry->next : head; + 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 won't cut the list + */ +static inline void list_cut_position(struct list_head *list, + struct list_head *head, struct list_head *entry) +{ + BUG_ON(list_empty(head)); + if (list_is_singular(head)) + BUG_ON(head->next != entry && head != entry); + 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 *head) { -- 1.5.6.rc2.15.g457bb.dirty