flow, tcp: Consolidate flow pointer<->index helpers

Both tcp.c and tcp_splice.c define CONN_IDX() variants to find the index
of their connection structures in the connection table, now become the
unified flow table.  We can easily combine these into a common helper.
While we're there, add some trickery for some additional type safety.

They also define their own CONN() versions, which aren't so easily combined
since they need to return different types, but we can have them use a
common helper.

In the process, we standardise on always using an unsigned type to store
the connection / flow index, which makes more sense.  tcp.c's conn_at_idx()
remains for now, but we change its parameter to unsigned to match.  That in
turn means we can remove a check for negative values from it.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

1 files changed, 25 insertions, 0 deletions

diff --git a/flow_table.h b/flow_table.h
index c4c646b..5e897bd 100644
--- a/flow_table.h
+++ b/flow_table.h
@@ -22,4 +22,29 @@ union flow {
 /* Global Flow Table */
 extern union flow flowtab[];
 
+
+/** flow_idx - Index of flow from common structure
+ * @f:	Common flow fields pointer
+ *
+ * Return: index of @f in the flow table
+ */
+static inline unsigned flow_idx(const struct flow_common *f)
+{
+	return (union flow *)f - flowtab;
+}
+
+/** FLOW_IDX - Find the index of a flow
+ * @f_:	Flow pointer, either union flow * or protocol specific
+ *
+ * Return: index of @f in the flow table
+ */
+#define FLOW_IDX(f_)		(flow_idx(&(f_)->f))
+
+/** FLOW - Flow entry at a given index
+ * @idx:	Flow index
+ *
+ * Return: pointer to entry @idx in the flow table
+ */
+#define FLOW(idx)		(&flowtab[(idx)])
+
 #endif /* FLOW_TABLE_H */