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Commit fae9c791 authored by Li Zefan's avatar Li Zefan Committed by Paul E. McKenney
Browse files

cgroup: Fix an RCU warning in alloc_css_id() 



With CONFIG_PROVE_RCU=y, a warning can be triggered:

  # mount -t cgroup -o memory xxx /mnt
  # mkdir /mnt/0

...
kernel/cgroup.c:4442 invoked rcu_dereference_check() without protection!
...

This is a false-positive. It's safe to directly access parent_css->id.

Signed-off-by: default avatarLi Zefan <lizf@cn.fujitsu.com>
Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
parent 9a9686b6

kernel/cgroup.c

+2 −2
Original line number Diff line number Diff line
@@ -4561,13 +4561,13 @@ static int alloc_css_id(struct cgroup_subsys *ss, struct cgroup *parent, 
{

	int subsys_id, i, depth = 0;

	struct cgroup_subsys_state *parent_css, *child_css;

	struct css_id *child_id, *parent_id = NULL;

	struct css_id *child_id, *parent_id;



	subsys_id = ss->subsys_id;

	parent_css = parent->subsys[subsys_id];

	child_css = child->subsys[subsys_id];

	depth = css_depth(parent_css) + 1;

	parent_id = parent_css->id;

	depth = parent_id->depth;



	child_id = get_new_cssid(ss, depth);

	if (IS_ERR(child_id))