Looks like we can shrink this struct with 8 bytes by reordering:

struct HtpState_ {
        htp_connp_t *              connp;                /*     0     8 */
        Flow *                     f;                    /*     8     8 */
        uint16_t                   flags;                /*    16     2 */

        /* XXX 6 bytes hole, try to pack */

        uint64_t                   transaction_cnt;      /*    24     8 */
        uint64_t                   transaction_done;     /*    32     8 */
        uint16_t                   store_tx_id;          /*    40     2 */

        /* XXX 6 bytes hole, try to pack */

        FileContainer *            files_ts;             /*    48     8 */
        FileContainer *            files_tc;             /*    56     8 */
        /* --- cacheline 1 boundary (64 bytes) --- */
        struct HTPCfgRec_ *        cfg;                  /*    64     8 */

        /* size: 72, cachelines: 2, members: 9 */
        /* sum members: 60, holes: 2, sum holes: 12 */
        /* last cacheline: 8 bytes */
};