From: Xiao Liang <redacted>
Date: Thu, 13 Feb 2025 17:55:32 +0800

On Thu, Feb 13, 2025 at 4:37 PM Xiao Liang [off-list ref] wrote:

quoted

On Thu, Feb 13, 2025 at 3:05 PM Kuniyuki Iwashima [off-list ref] wrote:

quoted

[...]

quoted

quoted

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)

Will remove this line.

However, fb tunnel of ip6_tunnel, ip6_vti and sit can have
tunnel->net == NULL here. Take ip6_tunnel for example:

ip6_tnl_init_net()
    -> ip6_fb_tnl_dev_init()
    -> register_netdev()
        -> register_netdevice()
            -> ip6_tnl_dev_init()

This code path (including ip6_fb_tnl_dev_init()) doesn't set
tunnel->net. But for ip6_gre, ip6gre_fb_tunnel_init() does.

Ah, okay.  Then, let's set net in a single place, which would
be better than spreading net assignment and adding null check
in ->ndo_init(), and maybe apply the same to IPv4 tunnels ?