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>

3 files changed, 31 insertions, 4 deletions

diff --git a/net/tipc/bcast.c b/net/tipc/bcast.c
index 0052c0747d05..a5883b1452ff 100644
--- a/net/tipc/bcast.c
+++ b/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);
         }
 
diff --git a/net/tipc/discover.c b/net/tipc/discover.c
index 64c20284e0f7..1657f0e795ff 100644
--- a/net/tipc/discover.c
+++ b/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);
diff --git a/net/tipc/msg.h b/net/tipc/msg.h
index b23619fab968..7ee6ae238147 100644
--- a/net/tipc/msg.h
+++ b/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