Re: [PATCH net-next 4/9] netconsole: move netpoll_local_ip_unset() as netcons_local_ip_unset()

[Gustavo Luiz Duarte]

On Fri, Jul 24, 2026 at 4:05 PM Breno Leitao <leitao@xxxxxxxxxx> wrote:
>
> Move netpoll_local_ip_unset() from netpoll to netconsole and rename it
> to netcons_local_ip_unset();
>
> The body is otherwise unchanged, only the comment's setup-function
> reference is updated.
>
> Signed-off-by: Breno Leitao <leitao@xxxxxxxxxx>
> ---
>  drivers/net/netconsole.c | 19 ++++++++++++++++++-
>  include/linux/netpoll.h  |  1 -
>  net/core/netpoll.c       | 18 ------------------
>  3 files changed, 18 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c
> index 3a7a2cafc6276..70f9c5bfb3720 100644
> --- a/drivers/net/netconsole.c
> +++ b/drivers/net/netconsole.c
> @@ -351,6 +351,23 @@ static void netconsole_skb_pool_flush(struct netconsole_target *nt)
>         skb_queue_purge_reason(&nt->skb_pool, SKB_CONSUMED);
>  }
>
> +/*
> + * Test whether the caller left np->local_ip unset, so that
> + * netcons_netpoll_setup() should auto-populate it from the egress device.
> + *
> + * np->local_ip is a union of __be32 (IPv4) and struct in6_addr (IPv6),
> + * so an IPv6 address whose first 4 bytes are zero (e.g. ::1, ::2,
> + * IPv4-mapped ::ffff:a.b.c.d) must not be tested via the IPv4 arm —
> + * doing so would misclassify a caller-supplied address as unset and
> + * silently overwrite it with whatever address the device exposes.
> + */
> +static bool netcons_local_ip_unset(const struct netpoll *np)
> +{
> +       if (np->ipv6)
> +               return ipv6_addr_any(&np->local_ip.in6);
> +       return !np->local_ip.ip;
> +}


This whole checking if it is all zeroes in netcons_local_ip_unset()
looks very cumbersome.
Perhaps instead of storing 'bool ipv6' we could have something like
'u8 family', which would contain AF_INET for ipv4, AF_INET6 for ipv6,
or AF_UNSPEC if unset.

But that would be another patch separate from this refactoring, so for
this patch:

Reviewed-by: Gustavo Luiz Duarte <gustavold@xxxxxxxxx>