On Tue, Aug 30, 2022 at 10:29:56AM +0300, Ilpo Järvinen wrote:
> -static int serial_rs485_from_user(struct serial_rs485 *rs485,
> +static int serial_rs485_from_user(struct kserial_rs485 *rs485,
> const struct serial_rs485 __user *rs485_user)
> {
> - if (copy_from_user(rs485, rs485_user, sizeof(*rs485)))
> + struct serial_rs485 rs485_uapi;
> +
> + if (copy_from_user(&rs485_uapi, rs485_user, sizeof(*rs485)))
> return -EFAULT;
>
> + *rs485 = *((struct kserial_rs485 *)&rs485_uapi);
Ah, you are mapping this on top of the existing structure, so there was
no padding in the original one, why say that?
> +/*
> + * Compile-time asserts for struct kserial_rs485 and struct serial_rs485 equality
> + * (except padding).
This does not take into account any padding, in fact it's the opposite
as all of this:
> + */
> +static_assert(offsetof(struct kserial_rs485, flags) ==
> + offsetof(struct serial_rs485, flags));
> +static_assert(offsetof(struct kserial_rs485, delay_rts_before_send) ==
> + offsetof(struct serial_rs485, delay_rts_before_send));
> +static_assert(offsetof(struct kserial_rs485, delay_rts_after_send) ==
> + offsetof(struct serial_rs485, delay_rts_after_send));
> +static_assert(offsetof(struct kserial_rs485, addr_recv) ==
> + offsetof(struct serial_rs485, addr_recv));
> +static_assert(offsetof(struct kserial_rs485, addr_dest) ==
> + offsetof(struct serial_rs485, addr_dest));
> +static_assert(sizeof(struct kserial_rs485) <= sizeof(struct serial_rs485));
Is there to ensure that the offsets are exactly the same, no padding
involved anywhere.
So I don't understand the problem you are trying to solve here,
greg k-h
