Re: [PATCH v3 net 1/5] ipv6: Refactor common ip6gre_tunnel_init codes

David Miller
2015-09-11T22:31:02Z

From: Martin KaFai Lau <kafai@fb.com>
Date: Fri, 11 Sep 2015 11:06:17 -0700

> @@ -1460,19 +1474,16 @@ static void ip6gre_netlink_parms(struct nlattr *data[],
> static int ip6gre_tap_init(struct net_device *dev)
> {
> struct ip6_tnl *tunnel;
> + int ret;
>
> - tunnel = netdev_priv(dev);
> + ret = ip6gre_tunnel_init_common(dev);
> + if (ret)
> + return ret;
>
> - tunnel->dev = dev;
> - tunnel->net = dev_net(dev);
> - strcpy(tunnel->parms.name, dev->name);
> + tunnel = netdev_priv(dev);
>
> ip6gre_tnl_link_config(tunnel, 1);
>
> - dev->tstats = netdev_alloc_pcpu_stats(struct pcpu_sw_netstats);
> - if (!dev->tstats)
> - return -ENOMEM;
> -
> return 0;
> }

Is this really equivalent?

The existing code for GRE tap device initialization would use whatever
ether_setup() left in the broadcast address, it would leave
dev->dev_addr alone, and unconditionally use eth_header_ops.

You are changing behavior here, and it's been like this has been this
way long enough that I can't see clearly whether this is a valid
change or not. It probably is not.

Either way, even if it is valid, you have to document what is happening
here and why it's ok.