-void odp_flow_key_from_flow(struct odp_flow_key *, const struct flow *);
-void odp_flow_key_to_flow(const struct odp_flow_key *, struct flow *);
+/* By my calculations currently the longest valid nlattr-formatted flow key is
+ * 80 bytes long, so this leaves some safety margin.
+ *
+ * We allocate temporary on-stack buffers for flow keys as arrays of uint32_t
+ * to ensure proper 32-bit alignment for Netlink attributes. (An array of
+ * "struct nlattr" might not, in theory, be sufficiently aligned because it
+ * only contains 16-bit types.) */
+#define ODPUTIL_FLOW_KEY_BYTES 96
+#define ODPUTIL_FLOW_KEY_U32S DIV_ROUND_UP(ODPUTIL_FLOW_KEY_BYTES, 4)