From: Tejun Heo <tj@kernel.org>
To: lizefan@huawei.com, paul@paulmenage.org, glommer@parallels.com
Cc: containers@lists.linux-foundation.org, cgroups@vger.kernel.org,
peterz@infradead.org, mhocko@suse.cz,
linux-kernel@vger.kernel.org, Tejun Heo <tj@kernel.org>
Subject: [PATCH 1/3] cpuset: implement cgroup_rightmost_descendant()
Date: Thu, 3 Jan 2013 13:44:04 -0800 [thread overview]
Message-ID: <1357249446-25075-2-git-send-email-tj@kernel.org> (raw)
In-Reply-To: <1357249446-25075-1-git-send-email-tj@kernel.org>
Implement cgroup_rightmost_descendant() which returns the right most
descendant of the specified cgroup. This can be used to skip the
cgroup's subtree while iterating with
cgroup_for_each_descendant_pre().
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
---
include/linux/cgroup.h | 1 +
kernel/cgroup.c | 26 ++++++++++++++++++++++++++
2 files changed, 27 insertions(+)
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 7d73905..860ca0f 100644
--- a/include/linux/cgroup.h
+++ b/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/kernel/cgroup.c b/kernel/cgroup.c
index 4855892..6643f70 100644
--- a/kernel/cgroup.c
+++ b/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;
--
1.8.0.2
next prev parent reply other threads:[~2013-01-03 21:44 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-03 21:44 [PATCHSET] cpuset: drop cpuset->stack_list and ->parent, take#2 Tejun Heo
2013-01-03 21:44 ` Tejun Heo [this message]
2013-01-03 21:44 ` [PATCH 2/3] cpuset: replace cpuset->stack_list with cpuset_for_each_descendant_pre() Tejun Heo
2013-01-03 21:44 ` [PATCH 3/3] cpuset: remove cpuset->parent Tejun Heo
2013-01-06 9:27 ` [PATCHSET] cpuset: drop cpuset->stack_list and ->parent, take#2 Li Zefan
2013-01-07 16:47 ` Tejun Heo
2013-01-07 16:52 ` Tejun Heo
-- strict thread matches above, loose matches on Subject: below --
2012-11-28 22:26 [PATCHSET cgroup/for-3.8] cpuset: drop cpuset->stack_list and ->parent Tejun Heo
2012-11-28 22:26 ` [PATCH 1/3] cpuset: implement cgroup_rightmost_descendant() Tejun Heo
2012-12-03 16:03 ` Michal Hocko
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