unix_diag: Fixup RQLEN extension report

While it's not too late fix the recently added RQLEN diag extension
to report rqlen and wqlen in the same way as TCP does.

I.e. for listening sockets the ack backlog length (which is the input
queue length for socket) in rqlen and the max ack backlog length in
wqlen, and what the CINQ/OUTQ ioctls do for established.
Signed-off-by: NPavel Emelyanov <xemul@parallels.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/linux/unix_diag.h

@@ -46,4 +46,9 @@ struct unix_diag_vfs {
 	__u32	udiag_vfs_dev;
 };
 
+struct unix_diag_rqlen {
+	__u32	udiag_rqueue;
+	__u32	udiag_wqueue;
+};
+
 #endif

net/unix/diag.c

@@ -101,7 +101,18 @@ static int sk_diag_dump_icons(struct sock *sk, struct sk_buff *nlskb)
 
 static int sk_diag_show_rqlen(struct sock *sk, struct sk_buff *nlskb)
 {
-	RTA_PUT_U32(nlskb, UNIX_DIAG_RQLEN, sk->sk_receive_queue.qlen);
+	struct unix_diag_rqlen *rql;
+
+	rql = UNIX_DIAG_PUT(nlskb, UNIX_DIAG_RQLEN, sizeof(*rql));
+
+	if (sk->sk_state == TCP_LISTEN) {
+		rql->udiag_rqueue = sk->sk_receive_queue.qlen;
+		rql->udiag_wqueue = sk->sk_max_ack_backlog;
+	} else {
+		rql->udiag_rqueue = (__u32)unix_inq_len(sk);
+		rql->udiag_wqueue = (__u32)unix_outq_len(sk);
+	}
+
 	return 0;
 
 rtattr_failure: