dbc_user_setuid
if (copy_from_user(dbc_dev->payload, argp, sizeof(struct dbc_user_setuid)))
*dbc_dev->payload_size = dbc_dev->header_size + sizeof(struct dbc_user_setuid);
if (copy_to_user(argp, dbc_dev->payload, sizeof(struct dbc_user_setuid)))
#define DBCIOCUID _IOW(DBC_IOC_TYPE, 0x2, struct dbc_user_setuid)
struct dbc_user_setuid tmp;