Am Montag, 19. Oktober 2015, 20:40:17 schrieb Eric Dumazet:
> From: Eric Dumazet <eduma...@google.com>
> 
> Tom Herbert added SIT support to GRO with commit
> 19424e052fb4 ("sit: Add gro callbacks to sit_offload"),
> later reverted by Herbert Xu.
> 
> The problem came because Tom patch was building GRO
> packets without proper meta data : If packets were locally
> delivered, we would not care.
> 
> But if packets needed to be forwarded, GSO engine was not
> able to segment individual segments.
> 
> With the following patch, we correctly set skb->encapsulation
> and inner network header. We also update gso_type.
> 

I'm running 4.1.11 / 4.1.12 with this patch on top now since over a week. 
ISATAP works fine.
 

> Tested:
> 
> Server :
> netserver
> modprobe dummy
> ifconfig dummy0 8.0.0.1 netmask 255.255.255.0 up
> arp -s 8.0.0.100 4e:32:51:04:47:e5
> iptables -I INPUT -s 10.246.7.151 -j TEE --gateway 8.0.0.100
> ifconfig sixtofour0
> sixtofour0 Link encap:IPv6-in-IPv4
>           inet6 addr: 2002:af6:798::1/128 Scope:Global
>           inet6 addr: 2002:af6:798::/128 Scope:Global
>           UP RUNNING NOARP  MTU:1480  Metric:1
>           RX packets:411169 errors:0 dropped:0 overruns:0 frame:0
>           TX packets:409414 errors:0 dropped:0 overruns:0 carrier:0
>           collisions:0 txqueuelen:0
>           RX bytes:20319631739 (20.3 GB)  TX bytes:29529556 (29.5 MB)
> 
> Client :
> netperf -H 2002:af6:798::1 -l 1000 &
> 
> Checked on server traffic copied on dummy0 and verify segments were
> properly rebuilt, with proper IP headers, TCP checksums...
> 
> tcpdump on eth0 shows proper GRO aggregation takes place.
> 
> Signed-off-by: Eric Dumazet <eduma...@google.com>
> ---
>  net/ipv6/ip6_offload.c |   12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/net/ipv6/ip6_offload.c b/net/ipv6/ip6_offload.c
> index 08b62047c67f..eeca943f12dc 100644
> --- a/net/ipv6/ip6_offload.c
> +++ b/net/ipv6/ip6_offload.c
> @@ -264,6 +264,9 @@ static int ipv6_gro_complete(struct sk_buff *skb, int
> nhoff) struct ipv6hdr *iph = (struct ipv6hdr *)(skb->data + nhoff);
>       int err = -ENOSYS;
> 
> +     if (skb->encapsulation)
> +             skb_set_inner_network_header(skb, nhoff);
> +
>       iph->payload_len = htons(skb->len - nhoff - sizeof(*iph));
> 
>       rcu_read_lock();
> @@ -280,6 +283,13 @@ out_unlock:
>       return err;
>  }
> 
> +static int sit_gro_complete(struct sk_buff *skb, int nhoff)
> +{
> +     skb->encapsulation = 1;
> +     skb_shinfo(skb)->gso_type |= SKB_GSO_SIT;
> +     return ipv6_gro_complete(skb, nhoff);
> +}
> +
>  static struct packet_offload ipv6_packet_offload __read_mostly = {
>       .type = cpu_to_be16(ETH_P_IPV6),
>       .callbacks = {
> @@ -292,6 +302,8 @@ static struct packet_offload ipv6_packet_offload
> __read_mostly = { static const struct net_offload sit_offload = {
>       .callbacks = {
>               .gso_segment    = ipv6_gso_segment,
> +             .gro_receive    = ipv6_gro_receive,
> +             .gro_complete   = sit_gro_complete,
>       },
>  };

Thanks,
-- 
Wolfgang Walter
Studentenwerk München
Anstalt des öffentlichen Rechts
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