net: sched: act: mirred: add extack support

This patch adds extack support for TC mirred action.

Cc: David Ahern <dsahern@gmail.com>
Signed-off-by: Alexander Aring <aring@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sched/act_mirred.c

@@ -80,13 +80,17 @@ static int tcf_mirred_init(struct net *net, struct nlattr *nla,
 	bool exists = false;
 	int ret;
 
-	if (!nla)
+	if (!nla) {
+		NL_SET_ERR_MSG_MOD(extack, "Mirred requires attributes to be passed");
 		return -EINVAL;
-	ret = nla_parse_nested(tb, TCA_MIRRED_MAX, nla, mirred_policy, NULL);
+	}
+	ret = nla_parse_nested(tb, TCA_MIRRED_MAX, nla, mirred_policy, extack);
 	if (ret < 0)
 		return ret;
-	if (!tb[TCA_MIRRED_PARMS])
+	if (!tb[TCA_MIRRED_PARMS]) {
+		NL_SET_ERR_MSG_MOD(extack, "Missing required mirred parameters");
 		return -EINVAL;
+	}
 	parm = nla_data(tb[TCA_MIRRED_PARMS]);
 
 	exists = tcf_idr_check(tn, parm->index, a, bind);
@@ -102,6 +106,7 @@ static int tcf_mirred_init(struct net *net, struct nlattr *nla,
 	default:
 		if (exists)
 			tcf_idr_release(*a, bind);
+		NL_SET_ERR_MSG_MOD(extack, "Unknown mirred option");
 		return -EINVAL;
 	}
 	if (parm->ifindex) {
@@ -117,8 +122,10 @@ static int tcf_mirred_init(struct net *net, struct nlattr *nla,
 	}
 
 	if (!exists) {
-		if (!dev)
+		if (!dev) {
+			NL_SET_ERR_MSG_MOD(extack, "Specified device does not exist");
 			return -EINVAL;
+		}
 		ret = tcf_idr_create(tn, parm->index, est, a,
 				     &act_mirred_ops, bind, true);
 		if (ret)