tipc: Message rejection rework preparatory changes

This patch defines a few new message header manipulation routines,
and generalizes the usefulness of another, in preparation for upcoming
rework of TIPC's message rejection code.

Signed-off-by: Allan Stephens <allan.stephens@windriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/tipc/bcast.c

@@ -571,7 +571,7 @@ static int tipc_bcbearer_send(struct sk_buff *buf,
 		assert(tipc_cltr_bcast_nodes.count != 0);
 		bcbuf_set_acks(buf, tipc_cltr_bcast_nodes.count);
 		msg = buf_msg(buf);
-		msg_set_non_seq(msg);
+		msg_set_non_seq(msg, 1);
 		msg_set_mc_netid(msg, tipc_net_id);
 	}
 

net/tipc/discover.c

@@ -121,7 +121,7 @@ static struct sk_buff *tipc_disc_init_msg(u32 type,
 	if (buf) {
 		msg = buf_msg(buf);
 		msg_init(msg, LINK_CONFIG, type, DSC_H_SIZE, dest_domain);
-		msg_set_non_seq(msg);
+		msg_set_non_seq(msg, 1);
 		msg_set_req_links(msg, req_links);
 		msg_set_dest_domain(msg, dest_domain);
 		msg_set_bc_netid(msg, tipc_net_id);

net/tipc/msg.h

@@ -75,6 +75,14 @@ static inline void msg_set_bits(struct tipc_msg *m, u32 w,
 	m->hdr[w] |= htonl(val);
 }
 
+static inline void msg_swap_words(struct tipc_msg *msg, u32 a, u32 b)
+{
+	u32 temp = msg->hdr[a];
+
+	msg->hdr[a] = msg->hdr[b];
+	msg->hdr[b] = temp;
+}
+
 /*
  * Word 0
  */
@@ -119,9 +127,9 @@ static inline int msg_non_seq(struct tipc_msg *m)
 	return msg_bits(m, 0, 20, 1);
 }
 
-static inline void msg_set_non_seq(struct tipc_msg *m)
+static inline void msg_set_non_seq(struct tipc_msg *m, u32 n)
 {
-	msg_set_bits(m, 0, 20, 1, 1);
+	msg_set_bits(m, 0, 20, 1, n);
 }
 
 static inline int msg_dest_droppable(struct tipc_msg *m)
@@ -224,6 +232,25 @@ static inline void msg_set_seqno(struct tipc_msg *m, u32 n)
 	msg_set_bits(m, 2, 0, 0xffff, n);
 }
 
+/*
+ * TIPC may utilize the "link ack #" and "link seq #" fields of a short
+ * message header to hold the destination node for the message, since the
+ * normal "dest node" field isn't present.  This cache is only referenced
+ * when required, so populating the cache of a longer message header is
+ * harmless (as long as the header has the two link sequence fields present).
+ *
+ * Note: Host byte order is OK here, since the info never goes off-card.
+ */
+
+static inline u32 msg_destnode_cache(struct tipc_msg *m)
+{
+	return m->hdr[2];
+}
+
+static inline void msg_set_destnode_cache(struct tipc_msg *m, u32 dnode)
+{
+	m->hdr[2] = dnode;
+}
 
 /*
  * Words 3-10