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 <lrodriguez@xxxxxxxxxxx>
---
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
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