Re: [PATCH RFC 11/12] net: Remove all references to SKB_GSO_UDP.

From: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Date: Thu, 6 Jul 2017 13:57:20 -0400

On Thu, Jul 6, 2017 at 10:43 AM, David Miller [off-list ref] wrote:

quoted

From: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Date: Wed, 5 Jul 2017 12:27:11 -0400

quoted

quoted

quoted

--- a/net/ipv4/udp_offload.c
+++ b/net/ipv4/udp_offload.c

@@ -21,7 +21,7 @@ static struct sk_buff *__skb_udp_tunnel_segment(struct sk_buff *skb,
        __be16 new_protocol, bool is_ipv6)

In this file, can now remove all of udp4_ufo_fragment, and
udp6_ufo_fragment in net/ipv6.

I had missed that this is used for tunneling with skb_udp_tunnel_segment.
But the core codepath should no longer be hit once SKB_GSO_UDP
is removed.

Are you sure?  I'm pretty sure all of the code remaining after my
patch series is needed in order to handle doing TCP GRO through
UDP tunneling encapsulation.

Although the word "fragment" is in the function name, it's not doing
IP fragmentation.  Instead, it is "fragmenting" the batched UDP
encapsulated frame into a series of individual UDP encapsulated ones.

Isn't that case handled in the branch

        if (skb->encapsulation &&
            (skb_shinfo(skb)->gso_type &
             (SKB_GSO_UDP_TUNNEL|SKB_GSO_UDP_TUNNEL_CSUM))) {
                segs = skb_udp_tunnel_segment(skb, features, false);
                goto out;
        }

It appears to be in a quick test I ran with FOU.

You are correct, I respun the series with that code removed.

Thanks!