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

On Wed, 2012-10-17 at 15:11 -0400, Vlad Yasevich wrote:

On 10/17/2012 12:13 PM, Eric Dumazet wrote:

quoted

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

quoted

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.

The thing about this approach is that if there are any other protocols 
that could have to provide their own segmentation functionality, such 
functionality would always have to be part of the kernel.  I wasn't sure 
how much I liked that.

Well, an hypervisor probably has to handle IPv6, at least to a certain
extent.

Make this part a module of its own, or statically linked into vmlinux,
instead of adding some stubs in IPv6 'module'

quoted

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 ?

Which hash are you talking about?  I didn't add any hashes.

I suspect you didnt really understood what I said then.

packet_type structures are hashed into ptype_base[]

struct list_head *head = &ptype_base[ntohs(type) & PTYPE_HASH_MASK];

Now let say we split the structure into 2 parts.

ptype_base[] would be used for pre GRO/GSO stuff (packet handlers)

So we would need to add a second hash for the GRO/GSO stuff.