tipc: refactor function tipc_sk_anc_data_recv()

We refactor tipc_sk_anc_data_recv() to make it slightly more
comprehensible, but also to facilitate application of some additions
to the code in a future commit.
Reviewed-by: Xin Long <lucien.xin@gmail.com>
Tested-by: Hoang Le <hoang.h.le@dektech.com.au>
Signed-off-by: Jon Maloy <jmaloy@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/tipc/socket.c

@@ -1733,67 +1733,58 @@ static void tipc_sk_set_orig_addr(struct msghdr *m, struct sk_buff *skb)
 static int tipc_sk_anc_data_recv(struct msghdr *m, struct sk_buff *skb,
 				 struct tipc_sock *tsk)
 {
-	struct tipc_msg *msg;
-	u32 anc_data[3];
-	u32 err;
-	u32 dest_type;
-	int has_name;
-	int res;
+	struct tipc_msg *hdr;
+	u32 data[3] = {0,};
+	bool has_addr;
+	int dlen, rc;
 
 	if (likely(m->msg_controllen == 0))
 		return 0;
-	msg = buf_msg(skb);
 
-	/* Optionally capture errored message object(s) */
-	err = msg ? msg_errcode(msg) : 0;
-	if (unlikely(err)) {
-		anc_data[0] = err;
-		anc_data[1] = msg_data_sz(msg);
-		res = put_cmsg(m, SOL_TIPC, TIPC_ERRINFO, 8, anc_data);
-		if (res)
-			return res;
-		if (anc_data[1]) {
-			if (skb_linearize(skb))
-				return -ENOMEM;
-			msg = buf_msg(skb);
-			res = put_cmsg(m, SOL_TIPC, TIPC_RETDATA, anc_data[1],
-				       msg_data(msg));
-			if (res)
-				return res;
-		}
+	hdr = buf_msg(skb);
+	dlen = msg_data_sz(hdr);
+
+	/* Capture errored message object, if any */
+	if (msg_errcode(hdr)) {
+		if (skb_linearize(skb))
+			return -ENOMEM;
+		hdr = buf_msg(skb);
+		data[0] = msg_errcode(hdr);
+		data[1] = dlen;
+		rc = put_cmsg(m, SOL_TIPC, TIPC_ERRINFO, 8, data);
+		if (rc || !dlen)
+			return rc;
+		rc = put_cmsg(m, SOL_TIPC, TIPC_RETDATA, dlen, msg_data(hdr));
+		if (rc)
+			return rc;
 	}
 
-	/* Optionally capture message destination object */
-	dest_type = msg ? msg_type(msg) : TIPC_DIRECT_MSG;
-	switch (dest_type) {
+	/* Capture TIPC_SERVICE_ADDR/RANGE destination address, if any */
+	switch (msg_type(hdr)) {
 	case TIPC_NAMED_MSG:
-		has_name = 1;
-		anc_data[0] = msg_nametype(msg);
-		anc_data[1] = msg_namelower(msg);
-		anc_data[2] = msg_namelower(msg);
+		has_addr = true;
+		data[0] = msg_nametype(hdr);
+		data[1] = msg_namelower(hdr);
+		data[2] = data[1];
 		break;
 	case TIPC_MCAST_MSG:
-		has_name = 1;
-		anc_data[0] = msg_nametype(msg);
-		anc_data[1] = msg_namelower(msg);
-		anc_data[2] = msg_nameupper(msg);
+		has_addr = true;
+		data[0] = msg_nametype(hdr);
+		data[1] = msg_namelower(hdr);
+		data[2] = msg_nameupper(hdr);
 		break;
 	case TIPC_CONN_MSG:
-		has_name = !!tsk->conn_addrtype;
-		anc_data[0] = msg_nametype(&tsk->phdr);
-		anc_data[1] = msg_nameinst(&tsk->phdr);
-		anc_data[2] = anc_data[1];
+		has_addr = !!tsk->conn_addrtype;
+		data[0] = msg_nametype(&tsk->phdr);
+		data[1] = msg_nameinst(&tsk->phdr);
+		data[2] = data[1];
 		break;
 	default:
-		has_name = 0;
-	}
-	if (has_name) {
-		res = put_cmsg(m, SOL_TIPC, TIPC_DESTNAME, 12, anc_data);
-		if (res)
-			return res;
+		has_addr = false;
 	}
-
-	return 0;
+	if (!has_addr)
+		return 0;
+	return put_cmsg(m, SOL_TIPC, TIPC_DESTNAME, 12, data);
 }
 
 static struct sk_buff *tipc_sk_build_ack(struct tipc_sock *tsk)