net_sched: notify filter deletion when deleting a chain

When we delete a chain of filters, we need to notify
user-space we are deleting each filters in this chain
too.

Fixes: 32a4f5ecd738 ("net: sched: introduce chain object to uapi")
Cc: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sched/cls_api.c

@@ -1902,6 +1902,8 @@ replay:
 				RTM_NEWCHAIN, false);
 		break;
 	case RTM_DELCHAIN:
+		tfilter_notify_chain(net, skb, block, q, parent, n,
+				     chain, RTM_DELTFILTER);
 		/* Flush the chain first as the user requested chain removal. */
 		tcf_chain_flush(chain);
 		/* In case the chain was successfully deleted, put a reference