error: initialization of ‘long int (*)(struct file *, unsigned int, long unsigned int)’ from incompatible pointer type ‘int (*)(struct file *, unsigned int, long unsigned int)’ [-Werror=incompatible-pointer-types]
.unlocked_ioctl = sys_led_ioctl,
^~~~~~~~~~~~~
返回值類型錯誤，將返回值類型改為long int即可