MFD_NAME_PREFIX_LEN
#define MFD_NAME_MAX_LEN (NAME_MAX - MFD_NAME_PREFIX_LEN)
memcpy(name, MFD_NAME_PREFIX, MFD_NAME_PREFIX_LEN);
len = strncpy_from_user(&name[MFD_NAME_PREFIX_LEN], uname, MFD_NAME_MAX_LEN + 1);