net_cls: Use __dev_get_by_index()

We hold RTNL in tc_dump_tfilter(), we can avoid dev_hold()/dev_put()
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sched/cls_api.c

@@ -404,6 +404,7 @@ static int tcf_node_dump(struct tcf_proto *tp, unsigned long n,
 			     a->cb->nlh->nlmsg_seq, NLM_F_MULTI, RTM_NEWTFILTER);
 }
 
+/* called with RTNL */
 static int tc_dump_tfilter(struct sk_buff *skb, struct netlink_callback *cb)
 {
 	struct net *net = sock_net(skb->sk);
@@ -422,7 +423,7 @@ static int tc_dump_tfilter(struct sk_buff *skb, struct netlink_callback *cb)
 
 	if (cb->nlh->nlmsg_len < NLMSG_LENGTH(sizeof(*tcm)))
 		return skb->len;
-	if ((dev = dev_get_by_index(&init_net, tcm->tcm_ifindex)) == NULL)
+	if ((dev = __dev_get_by_index(&init_net, tcm->tcm_ifindex)) == NULL)
 		return skb->len;
 
 	if (!tcm->tcm_parent)
@@ -484,7 +485,6 @@ errout:
 	if (cl)
 		cops->put(q, cl);
 out:
-	dev_put(dev);
 	return skb->len;
 }