net: rtnetlink: plumb extended ack to doit function

Add netlink_ext_ack arg to rtnl_doit_func. Pass extack arg to nlmsg_parse
for doit functions that call it directly.

This is the first step to using extended error reporting in rtnetlink.
>From here individual subsystems can be updated to set netlink_ext_ack as
needed.

Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/addrlabel.c b/net/ipv6/addrlabel.c
index 6cb4ed9..07cd7d2 100644
--- a/net/ipv6/addrlabel.c
+++ b/net/ipv6/addrlabel.c
@@ -404,7 +404,8 @@ static const struct nla_policy ifal_policy[IFAL_MAX+1] = {
 	[IFAL_LABEL]		= { .len = sizeof(u32), },
 };
 
-static int ip6addrlbl_newdel(struct sk_buff *skb, struct nlmsghdr *nlh)
+static int ip6addrlbl_newdel(struct sk_buff *skb, struct nlmsghdr *nlh,
+			     struct netlink_ext_ack *extack)
 {
 	struct net *net = sock_net(skb->sk);
 	struct ifaddrlblmsg *ifal;
@@ -413,7 +414,8 @@ static int ip6addrlbl_newdel(struct sk_buff *skb, struct nlmsghdr *nlh)
 	u32 label;
 	int err = 0;
 
-	err = nlmsg_parse(nlh, sizeof(*ifal), tb, IFAL_MAX, ifal_policy, NULL);
+	err = nlmsg_parse(nlh, sizeof(*ifal), tb, IFAL_MAX, ifal_policy,
+			  extack);
 	if (err < 0)
 		return err;
 
@@ -521,7 +523,8 @@ static inline int ip6addrlbl_msgsize(void)
 		+ nla_total_size(4);	/* IFAL_LABEL */
 }
 
-static int ip6addrlbl_get(struct sk_buff *in_skb, struct nlmsghdr *nlh)
+static int ip6addrlbl_get(struct sk_buff *in_skb, struct nlmsghdr *nlh,
+			  struct netlink_ext_ack *extack)
 {
 	struct net *net = sock_net(in_skb->sk);
 	struct ifaddrlblmsg *ifal;
@@ -532,7 +535,8 @@ static int ip6addrlbl_get(struct sk_buff *in_skb, struct nlmsghdr *nlh)
 	struct ip6addrlbl_entry *p;
 	struct sk_buff *skb;
 
-	err = nlmsg_parse(nlh, sizeof(*ifal), tb, IFAL_MAX, ifal_policy, NULL);
+	err = nlmsg_parse(nlh, sizeof(*ifal), tb, IFAL_MAX, ifal_policy,
+			  extack);
 	if (err < 0)
 		return err;