Re: [PATCHv3] ipv6: Enable enough of the code to handle GSO when disabled.

[Eric Dumazet <eric.dumazet@gmail.com>]

On Wed, 2012-10-17 at 11:46 -0400, Vlad Yasevich wrote:

> This patch attempts to solve this by enabling just enough code so GSO
> is correctly processed.  However, I should point out that if IPv6 is
> simply blacklisted or not built for the kernel, this problem will
> still persist.

So I guess this should be done in a different way ?

We currently use a single structure (struct packet_type) to hold 
pointers to different methods. (The .func() field, and the gso/gro
stuff)

We probably need to split it in two parts, and make one part linked into
kernel, even if CONFIG_IPV6=n, so that GRO/GSO is fully IPv4/IPv6
functional.

By the way, do we really need a hash table for this ?
It seems we only have IPv4 (ETH_P_IP) and IPv6 (ETH_P_IPV6) to take care
of ?

This would remove some tests we currently have in GRO stack, and some
RCU stuff as well.
(GRO is slower if we have many af_packet sockets)

list_for_each_entry_rcu(ptype, head, list) {
    if (ptype->type != type || ptype->dev || !ptype->gro_receive)
        continue;
...

Adding a hook/test in ipv6_rcv() is ugly.