tipc: change signature of tunnelling reception function

After the earlier commits in this series related to the function
tipc_link_tunnel_rcv(), we can now go further and simplify its
signature.

The function now consumes all DUPLICATE packets, and only returns such
ORIGINAL packets that are ready for immediate delivery, i.e., no
more link level protocol processing needs to be done by the caller.
As a consequence, the the caller, tipc_rcv(), does not access the link
pointer after call return, and it becomes unnecessary to pass a link
pointer reference in the call. Instead, we now only pass it the tunnel
link's owner node, which is sufficient to find the destination link for
the tunnelled packet.

Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
Reviewed-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/tipc/link.c

@@ -78,7 +78,7 @@ static const char *link_unk_evt = "Unknown link event ";
 static void link_handle_out_of_seq_msg(struct tipc_link *l_ptr,
 				       struct sk_buff *buf);
 static void link_recv_proto_msg(struct tipc_link *l_ptr, struct sk_buff *buf);
-static int  tipc_link_tunnel_rcv(struct tipc_link **l_ptr,
+static int  tipc_link_tunnel_rcv(struct tipc_node *n_ptr,
 				 struct sk_buff **buf);
 static void link_set_supervision_props(struct tipc_link *l_ptr, u32 tolerance);
 static int  link_send_sections_long(struct tipc_port *sender,
@@ -1597,7 +1597,7 @@ deliver:
 			tipc_node_unlock(n_ptr);
 			continue;
 		case CHANGEOVER_PROTOCOL:
-			if (!tipc_link_tunnel_rcv(&l_ptr, &buf))
+			if (!tipc_link_tunnel_rcv(n_ptr, &buf))
 				break;
 			msg = buf_msg(buf);
 			seq_no = msg_seqno(msg);
@@ -2174,7 +2174,7 @@ exit:
  *  returned to the active link for delivery upwards.
  *  Owner node is locked.
  */
-static int tipc_link_tunnel_rcv(struct tipc_link **l_ptr,
+static int tipc_link_tunnel_rcv(struct tipc_node *n_ptr,
 				struct sk_buff **buf)
 {
 	struct sk_buff *tunnel_buf = *buf;
@@ -2186,15 +2186,9 @@ static int tipc_link_tunnel_rcv(struct tipc_link **l_ptr,
 	if (bearer_id >= MAX_BEARERS)
 		goto exit;
 
-	dest_link = (*l_ptr)->owner->links[bearer_id];
+	dest_link = n_ptr->links[bearer_id];
 	if (!dest_link)
 		goto exit;
-	if (dest_link == *l_ptr) {
-		pr_err("Unexpected changeover message on link <%s>\n",
-		       (*l_ptr)->name);
-		goto exit;
-	}
-	*l_ptr = dest_link;
 
 	if (msg_typ == DUPLICATE_MSG) {
 		tipc_link_dup_rcv(dest_link, tunnel_buf);