Re: [PATCH net-next v2 1/7] net: ip: make fib_validate_source() return drop reason

[Paolo Abeni <pabeni@redhat.com>]

On 10/7/24 09:46, Menglong Dong wrote:
> In this commit, we make fib_validate_source/__fib_validate_source return
> -reason instead of errno on error. As the return value of them can be
> -errno, 0, and 1, we can't make it return enum skb_drop_reason directly.
> 
> In the origin logic, if __fib_validate_source() return -EXDEV,
> LINUX_MIB_IPRPFILTER will be counted. And now, we need to adjust it by
> checking "reason == SKB_DROP_REASON_IP_RPFILTER". However, this will take
> effect only after the patch "net: ip: make ip_route_input_noref() return
> drop reasons", as we can't pass the drop reasons from
> fib_validate_source() to ip_rcv_finish_core() in this patch.
> 
> We set the errno to -EINVAL when fib_validate_source() is called and the
> validation fails, as the errno can be checked in the caller and now its
> value is -reason, which can lead misunderstand.
> 
> Following new drop reasons are added in this patch:
> 
>    SKB_DROP_REASON_IP_LOCAL_SOURCE
>    SKB_DROP_REASON_IP_INVALID_SOURCE
> 
> Signed-off-by: Menglong Dong <dongml2@chinatelecom.cn>

Looking at the next patches, I'm under the impression that the overall 
code will be simpler if you let __fib_validate_source() return directly 
a drop reason, and fib_validate_source(), too. Hard to be sure without 
actually do the attempt... did you try such patch by any chance?

Thanks!

Paolo