device_cgroup: remove direct access to cgroup->children

Currently, devcg::has_children() directly tests cgroup->children for
list emptiness.  The field is not a published field and scheduled to
go away.  In addition, the test isn't strictly correct as devcg should
only care about children which are visible to userland.

This patch converts has_children() to use css_next_child() instead.
The subtle incorrectness is noted and will be dealt with later.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Aristeu Rozanski <aris@redhat.com>
Acked-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Acked-by: Li Zefan <lizefan@huawei.com>
This commit is contained in:
Tejun Heo 2014-05-16 13:22:48 -04:00
parent ea280e7b40
commit 5877019d97

View File

@ -589,9 +589,17 @@ static int propagate_exception(struct dev_cgroup *devcg_root,
static inline bool has_children(struct dev_cgroup *devcgroup)
{
struct cgroup *cgrp = devcgroup->css.cgroup;
bool ret;
return !list_empty(&cgrp->children);
/*
* FIXME: There may be lingering offline csses and this function
* may return %true when there isn't any userland-visible child
* which is incorrect for our purposes.
*/
rcu_read_lock();
ret = css_next_child(NULL, &devcgroup->css);
rcu_read_unlock();
return ret;
}
/*