Fix TEQL oops.

[PKT_SCHED]: Fix OOPS when removing devices from a teql queuing discipline

[ Upstream commit: 4f9f8311 ]

tecl_reset() is called from deactivate and qdisc is set to noop already,
but subsequent teql_xmit does not know about it and dereference private
data as teql qdisc and thus oopses.
not catch it first :)
Signed-off-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

net/sched/sch_teql.c

@@ -249,6 +249,9 @@ __teql_resolve(struct sk_buff *skb, struct sk_buff *skb_res, struct net_device *
 static __inline__ int
 teql_resolve(struct sk_buff *skb, struct sk_buff *skb_res, struct net_device *dev)
 {
+	if (dev->qdisc == &noop_qdisc)
+		return -ENODEV;
+
 	if (dev->hard_header == NULL ||
 	    skb->dst == NULL ||
 	    skb->dst->neighbour == NULL)