udp_diag: implement idiag_get_info for udp/udplite to get queue information

When we use netlink to monitor queue information for udp socket,
idiag_rqueue and idiag_wqueue of inet_diag_msg are returned with 0.

Keep consistent with netstat, just return back allocated rmem/wmem size.
Signed-off-by: NShan Wei <davidshan@tencent.com>
Acked-by: NPavel Emelyanov <xemul@parallels.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/inet_diag.c

@@ -141,7 +141,7 @@ int inet_sk_diag_fill(struct sock *sk, struct inet_connection_sock *icsk,
 			goto rtattr_failure;
 
 	if (icsk == NULL) {
-		r->idiag_rqueue = r->idiag_wqueue = 0;
+		handler->idiag_get_info(sk, r, NULL);
 		goto out;
 	}
 

net/ipv4/udp_diag.c

@@ -146,9 +146,17 @@ static int udp_diag_dump_one(struct sk_buff *in_skb, const struct nlmsghdr *nlh,
 	return udp_dump_one(&udp_table, in_skb, nlh, req);
 }
 
+static void udp_diag_get_info(struct sock *sk, struct inet_diag_msg *r,
+		void *info)
+{
+	r->idiag_rqueue = sk_rmem_alloc_get(sk);
+	r->idiag_wqueue = sk_wmem_alloc_get(sk);
+}
+
 static const struct inet_diag_handler udp_diag_handler = {
 	.dump		 = udp_diag_dump,
 	.dump_one	 = udp_diag_dump_one,
+	.idiag_get_info  = udp_diag_get_info,
 	.idiag_type	 = IPPROTO_UDP,
 };
 
@@ -167,6 +175,7 @@ static int udplite_diag_dump_one(struct sk_buff *in_skb, const struct nlmsghdr *
 static const struct inet_diag_handler udplite_diag_handler = {
 	.dump		 = udplite_diag_dump,
 	.dump_one	 = udplite_diag_dump_one,
+	.idiag_get_info  = udp_diag_get_info,
 	.idiag_type	 = IPPROTO_UDPLITE,
 };