dbc_user_nonce
if (copy_from_user(dbc_dev->payload, argp, sizeof(struct dbc_user_nonce)))
if (copy_to_user(argp, dbc_dev->payload, sizeof(struct dbc_user_nonce)))
*dbc_dev->payload_size = dbc_dev->header_size + sizeof(struct dbc_user_nonce);
#define DBCIOCNONCE _IOWR(DBC_IOC_TYPE, 0x1, struct dbc_user_nonce)
struct dbc_user_nonce tmp = {