On 12/18/2014 12:51 AM, Jason Wang wrote:
>
>
> ----- Original Message -----
>> Now that UFO is split into v4 and v6 parts, we can bring
>> back v4 support without any trouble.
>>
>> Continue to handle legacy applications by selecting the
>> IPv6 fragment id but do not change the gso type. Thist
>> makes sure that two legacy VMs may still communicate.
>>
>> Based on original work from Ben Hutchings.
>>
>> Fixes: 88e0e0e5aa7a ("drivers/net: Disable UFO through virtio")
>> CC: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
>> Signed-off-by: Vladislav Yasevich <vyasevic@xxxxxxxxxx>
>> ---
>> drivers/net/tun.c | 26 ++++++++++++++------------
>> 1 file changed, 14 insertions(+), 12 deletions(-)
>>
>> diff --git a/drivers/net/tun.c b/drivers/net/tun.c
>> index 9dd3746..8c32fca 100644
>> --- a/drivers/net/tun.c
>> +++ b/drivers/net/tun.c
>> @@ -175,7 +175,7 @@ struct tun_struct {
>> struct net_device *dev;
>> netdev_features_t set_features;
>> #define TUN_USER_FEATURES (NETIF_F_HW_CSUM|NETIF_F_TSO_ECN|NETIF_F_TSO| \
>> - NETIF_F_TSO6)
>> + NETIF_F_TSO6|NETIF_F_UFO)
>>
>> int vnet_hdr_sz;
>> int sndbuf;
>> @@ -1152,20 +1152,15 @@ static ssize_t tun_get_user(struct tun_struct *tun,
>> struct tun_file *tfile,
>> skb_shinfo(skb)->gso_type = SKB_GSO_TCPV6;
>> break;
>> case VIRTIO_NET_HDR_GSO_UDP:
>> - {
>> - static bool warned;
>> -
>> - if (!warned) {
>> - warned = true;
>> - netdev_warn(tun->dev,
>> - "%s: using disabled UFO feature; please fix this program\n",
>> - current->comm);
>> - }
>> skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
>> - if (skb->protocol == htons(ETH_P_IPV6))
>> + if (vlan_get_protocol(skb) == htons(ETH_P_IPV6)) {
>
> This probably means UDPv6 with vlan does not work well, looks like another
> independent fixe and also for stable.
Ok. I can split this out.
>> + /* This allows legacy application to work.
>> + * Do not change the gso_type as it may
>> + * not be upderstood by legacy applications.
>> + */
>
> Isn't this an issue that we use SKB_GSO_UDP for a UDPv6 packet? Especially
> consider we want to fix UFOv6 in the future? We probably can use
> SKB_GSO_UDP6 here and try to fix it in tun_put_user() if a legacy userspace
> is detected.
There is a slight problem with this. This will force fragmentation of IPv6
traffic between VMs since UFO6 wouldn't be enabled on a destination device.
So, suddenly older VMs will see a performance regression for large UDPv6 traffic.
With this code, a legacy VM will continue to receive large UDPv6 traffic.
New VMs will have an updated virtio-net which will reset the gso type on input.
>> ipv6_proxy_select_ident(skb);
>
> Question still for vlan, is network header correctly set here? Looks like
> ipv6_proxy_select_ident() depends on correct network header to work.
>> +
Yes, you are right... I wonder how that worked. I'll re-test.
Thanks
-vlad
}
>> break;
>> - }
>> default:
>> tun->dev->stats.rx_frame_errors++;
>> kfree_skb(skb);
>> @@ -1273,6 +1268,8 @@ static ssize_t tun_put_user(struct tun_struct *tun,
>> gso.gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
>> else if (sinfo->gso_type & SKB_GSO_TCPV6)
>> gso.gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
>> + else if (sinfo->gso_type & SKB_GSO_UDP)
>> + gso.gso_type = VIRTIO_NET_HDR_GSO_UDP;
>> else {
>> pr_err("unexpected GSO type: "
>> "0x%x, gso_size %d, hdr_len %d\n",
>> @@ -1780,6 +1777,11 @@ static int set_offload(struct tun_struct *tun,
>> unsigned long arg)
>> features |= NETIF_F_TSO6;
>> arg &= ~(TUN_F_TSO4|TUN_F_TSO6);
>> }
>> +
>> + if (arg & TUN_F_UFO) {
>> + features |= NETIF_F_UFO;
>> + arg &= ~TUN_F_UFO;
>> + }
>> }
>>
>> /* This gives the user a way to test for new features in future by
>> --
>> 1.9.3
>>
>> --
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