cgroup: minor tweak for logic to get cgroup css

We could only handle the case that css exists
and css_try_get_online() fails.

Signed-off-by: Peng Wang <rocking@whu.edu.cn>
Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 3c3d92d..21ddf30 100644 (file)
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -488,7 +488,7 @@ static struct cgroup_subsys_state *cgroup_tryget_css(struct cgroup *cgrp,
 
        rcu_read_lock();
        css = cgroup_css(cgrp, ss);
-       if (!css || !css_tryget_online(css))
+       if (css && !css_tryget_online(css))
                css = NULL;
        rcu_read_unlock();