Re: [PATCH net-next v9 06/11] net: ipv6: Use link netns in newlink() of rtnl_link_ops

[Kuniyuki Iwashima]

From: Xiao Liang <shaw.leon@xxxxxxxxx>
Date: Mon, 10 Feb 2025 21:29:57 +0800
> When link_net is set, use it as link netns instead of dev_net(). This
> prepares for rtnetlink core to create device in target netns directly,
> in which case the two namespaces may be different.
> 
> Set correct netns in priv before registering device, and avoid
> overwriting it in ndo_init() path.
> 
> Signed-off-by: Xiao Liang <shaw.leon@xxxxxxxxx>
> ---
>  net/ipv6/ip6_gre.c    | 20 ++++++++++----------
>  net/ipv6/ip6_tunnel.c | 13 ++++++++-----
>  net/ipv6/ip6_vti.c    | 10 ++++++----
>  net/ipv6/sit.c        | 11 +++++++----
>  4 files changed, 31 insertions(+), 23 deletions(-)
> 
> diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c
> index 863852abe8ea..108600dc716f 100644
> --- a/net/ipv6/ip6_gre.c
> +++ b/net/ipv6/ip6_gre.c
> @@ -1498,7 +1498,8 @@ static int ip6gre_tunnel_init_common(struct net_device *dev)
>  	tunnel = netdev_priv(dev);
>  
>  	tunnel->dev = dev;
> -	tunnel->net = dev_net(dev);
> +	if (!tunnel->net)
> +		tunnel->net = dev_net(dev);

Same question as patch 5 for here and other parts.
Do we need this check and assignment ?

ip6gre_newlink_common
-> nt->net = dev_net(dev)
-> register_netdevice
  -> ndo_init / ip6gre_tunnel_init()
    -> ip6gre_tunnel_init_common
      -> tunnel->net = dev_net(dev)