[PATCH][RSDL-mm 1/6] lists: add list splice tail

[Con Kolivas <kernel@kolivas.org>]

From: Con Kolivas <kernel@kolivas.org>

Add a list_splice_tail variant of list_splice.

Patch-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Con Kolivas <kernel@kolivas.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: "Siddha, Suresh B" <suresh.b.siddha@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/list.h |   42 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

Index: linux-2.6.21-rc3-mm2/include/linux/list.h
===================================================================
--- linux-2.6.21-rc3-mm2.orig/include/linux/list.h	2007-03-16 23:27:49.000000000 +1100
+++ linux-2.6.21-rc3-mm2/include/linux/list.h	2007-03-16 23:27:51.000000000 +1100
@@ -333,6 +333,20 @@ static inline void __list_splice(struct 
 	at->prev = last;
 }
 
+static inline void __list_splice_tail(struct list_head *list,
+				      struct list_head *head)
+{
+	struct list_head *first = list->next;
+	struct list_head *last = list->prev;
+	struct list_head *at = head->prev;
+
+	first->prev = at;
+	at->next = first;
+
+	last->next = head;
+	head->prev = last;
+}
+
 /**
  * list_splice - join two lists
  * @list: the new list to add.
@@ -345,6 +359,18 @@ static inline void list_splice(struct li
 }
 
 /**
+ * list_splice_tail - join two lists at one's tail
+ * @list: the new list to add.
+ * @head: the place to add it in the first list.
+ */
+static inline void list_splice_tail(struct list_head *list,
+				    struct list_head *head)
+{
+	if (!list_empty(list))
+		__list_splice_tail(list, head);
+}
+
+/**
  * list_splice_init - join two lists and reinitialise the emptied list.
  * @list: the new list to add.
  * @head: the place to add it in the first list.
@@ -417,6 +443,22 @@ static inline void list_splice_init_rcu(
 }
 
 /**
+ * list_splice_tail_init - join 2 lists at one's tail & reinitialise emptied
+ * @list: the new list to add.
+ * @head: the place to add it in the first list.
+ *
+ * The list at @list is reinitialised
+ */
+static inline void list_splice_tail_init(struct list_head *list,
+					 struct list_head *head)
+{
+	if (!list_empty(list)) {
+		__list_splice_tail(list, head);
+		INIT_LIST_HEAD(list);
+	}
+}
+
+/**
  * list_entry - get the struct for this entry
  * @ptr:	the &struct list_head pointer.
  * @type:	the type of the struct this is embedded in.

-- 
-ck