Re: [PATCH v2 net 3/4] neighbour: Don't render blackhole_netdev via RTM_GETNEIGHTBL.

[Ido Schimmel <idosch@nvidia.com>]

On Tue, Sep 08, 2026 at 09:12:47PM +0000, Kuniyuki Iwashima wrote:
> The cited commits started to initialise blackhole_netdev with
> neigh_parms_alloc().
> 
> This is visible in init_net as the ifindex==0 entries via
> RTM_GETNEIGHTBL:
> 
>   # ynl --family rt-neigh --dump getneightbl --output-json \
>     | jq '.[] | select(.parms.ifindex == 0)
>               | {name: .name, ifindex: .parms.ifindex}'
>   {
>     "name": "arp_cache",
>     "ifindex": 0
>   }
>   {
>     "name": "ndisc_cache",
>     "ifindex": 0
>   }
> 
> For RTM_SETNEIGHTBL, ifindex being 0 means wildcard.
> 
> Let's skip blackhole_netdev's parms in neightbl_dump_info().
> 
> Note that lookup_neigh_parms() does not need the same change
> because the default parms is always the first entry and matches
> with ifindex == 0.
> 
> Fixes: e5f80fcf869a ("ipv6: give an IPv6 dev to blackhole_netdev")
> Fixes: 22600596b675 ("ipv4: give an IPv4 dev to blackhole_netdev")
> Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>

Reviewed-by: Ido Schimmel <idosch@nvidia.com>