From 1ea14b2fdb4912e1379c25503c8a3d0189d8d821 Mon Sep 17 00:00:00 2001
From: Tejun Heo <tj@kernel.org>
Date: Mon, 7 Jan 2013 08:49:33 -0800
Subject: [PATCH] --- yaml --- r: 350317 b: refs/heads/master c:
 12a9d2fef1d35770d3cdc2cd1faabb83c45bc0fa h: refs/heads/master i:   350315:
 5443e6bce69941f6112a0a675ae52748a8bfe009 v: v3

---
 [refs]                       |  2 +-
 trunk/include/linux/cgroup.h |  1 +
 trunk/kernel/cgroup.c        | 26 ++++++++++++++++++++++++++
 3 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index 6073e5a536c0..476feb229710 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: d5b1fe68baa7213f198e5be8cd1a1037258ab2c8
+refs/heads/master: 12a9d2fef1d35770d3cdc2cd1faabb83c45bc0fa
diff --git a/trunk/include/linux/cgroup.h b/trunk/include/linux/cgroup.h
index 942e68705577..8118a3120378 100644
--- a/trunk/include/linux/cgroup.h
+++ b/trunk/include/linux/cgroup.h
@@ -558,6 +558,7 @@ static inline struct cgroup* task_cgroup(struct task_struct *task,
 
 struct cgroup *cgroup_next_descendant_pre(struct cgroup *pos,
 					  struct cgroup *cgroup);
+struct cgroup *cgroup_rightmost_descendant(struct cgroup *pos);
 
 /**
  * cgroup_for_each_descendant_pre - pre-order walk of a cgroup's descendants
diff --git a/trunk/kernel/cgroup.c b/trunk/kernel/cgroup.c
index 4855892798fd..6643f7053454 100644
--- a/trunk/kernel/cgroup.c
+++ b/trunk/kernel/cgroup.c
@@ -3017,6 +3017,32 @@ struct cgroup *cgroup_next_descendant_pre(struct cgroup *pos,
 }
 EXPORT_SYMBOL_GPL(cgroup_next_descendant_pre);
 
+/**
+ * cgroup_rightmost_descendant - return the rightmost descendant of a cgroup
+ * @pos: cgroup of interest
+ *
+ * Return the rightmost descendant of @pos.  If there's no descendant,
+ * @pos is returned.  This can be used during pre-order traversal to skip
+ * subtree of @pos.
+ */
+struct cgroup *cgroup_rightmost_descendant(struct cgroup *pos)
+{
+	struct cgroup *last, *tmp;
+
+	WARN_ON_ONCE(!rcu_read_lock_held());
+
+	do {
+		last = pos;
+		/* ->prev isn't RCU safe, walk ->next till the end */
+		pos = NULL;
+		list_for_each_entry_rcu(tmp, &last->children, sibling)
+			pos = tmp;
+	} while (pos);
+
+	return last;
+}
+EXPORT_SYMBOL_GPL(cgroup_rightmost_descendant);
+
 static struct cgroup *cgroup_leftmost_descendant(struct cgroup *pos)
 {
 	struct cgroup *last;