From: Tejun Heo <tj@kernel.org>
Date: Mon, 19 Nov 2012 16:13:36 +0000 (-0800)
Subject: cgroup: lock cgroup_mutex in cgroup_init_subsys()
X-Git-Tag: firefly_0821_release~3680^2~1492^2~27
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=648bb56d076b;p=firefly-linux-kernel-4.4.55.git

cgroup: lock cgroup_mutex in cgroup_init_subsys()

Make cgroup_init_subsys() grab cgroup_mutex while initializing a
subsystem so that all helpers and callbacks are called under the
context they expect.  This isn't strictly necessary as
cgroup_init_subsys() doesn't race with anybody but will allow adding
lockdep assertions.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
---

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 6cc693b91c4a..09751657abdc 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -4317,6 +4317,8 @@ static void __init cgroup_init_subsys(struct cgroup_subsys *ss)
 
 	printk(KERN_INFO "Initializing cgroup subsys %s\n", ss->name);
 
+	mutex_lock(&cgroup_mutex);
+
 	/* init base cftset */
 	cgroup_init_cftsets(ss);
 
@@ -4346,6 +4348,8 @@ static void __init cgroup_init_subsys(struct cgroup_subsys *ss)
 	if (ss->post_create)
 		ss->post_create(dummytop);
 
+	mutex_unlock(&cgroup_mutex);
+
 	/* this function shouldn't be used with modular subsystems, since they
 	 * need to register a subsys_id, among other things */
 	BUG_ON(ss->module);