net_sched: act: refuse to remove bound action outside

When an action is bonnd to a filter, there is no point to
remove it outside. Currently we just silently decrease the refcnt,
we should reject this explicitly with EPERM.

Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/act_api.h b/include/net/act_api.h
index 969cac6..3ee4c92 100644
--- a/include/net/act_api.h
+++ b/include/net/act_api.h
@@ -109,7 +109,7 @@
 
 int tcf_register_action(struct tc_action_ops *a, unsigned int mask);
 int tcf_unregister_action(struct tc_action_ops *a);
-void tcf_action_destroy(struct list_head *actions, int bind);
+int tcf_action_destroy(struct list_head *actions, int bind);
 int tcf_action_exec(struct sk_buff *skb, const struct list_head *actions,
 		    struct tcf_result *res);
 int tcf_action_init(struct net *net, struct nlattr *nla,