flow: Make unified version of flow table compaction

tcp_table_compact() will move entries in the connection/flow table to keep
it compact when other entries are removed.  The moved entries need not have
the same type as the flow removed, so it needs to be able to handle moving
any type of flow.  Therefore, move it to flow.c rather than being
purportedly TCP specific.

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

1 files changed, 39 insertions, 0 deletions

diff --git a/flow.c b/flow.c
index 5bb7173..534638b 100644
--- a/flow.c
+++ b/flow.c
@@ -27,3 +27,42 @@ static_assert(ARRAY_SIZE(flow_type_str) == FLOW_NUM_TYPES,
 
 /* Global Flow Table */
 union flow flowtab[FLOW_MAX];
+
+/**
+ * flow_table_compact() - Perform compaction on flow table
+ * @c:		Execution context
+ * @hole:	Pointer to recently closed flow
+ */
+void flow_table_compact(struct ctx *c, union flow *hole)
+{
+	union flow *from;
+
+	if (FLOW_IDX(hole) == --c->flow_count) {
+		debug("flow: table compaction: maximum index was %u (%p)",
+		      FLOW_IDX(hole), (void *)hole);
+		memset(hole, 0, sizeof(*hole));
+		return;
+	}
+
+	from = flowtab + c->flow_count;
+	memcpy(hole, from, sizeof(*hole));
+
+	switch (from->f.type) {
+	case FLOW_TCP:
+		tcp_tap_conn_update(c, &from->tcp, &hole->tcp);
+		break;
+	case FLOW_TCP_SPLICE:
+		tcp_splice_conn_update(c, &hole->tcp_splice);
+		break;
+	default:
+		die("Unexpected %s in tcp_table_compact()",
+		    FLOW_TYPE(&from->f));
+	}
+
+	debug("flow: table compaction (%s): old index %u, new index %u, "
+	      "from: %p, to: %p",
+	      FLOW_TYPE(&from->f), FLOW_IDX(from), FLOW_IDX(hole),
+	      (void *)from, (void *)hole);
+
+	memset(from, 0, sizeof(*from));
+}