netdev - Re: [PATCH] virtio: Work around frames incorrectly marked as gso

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Date:   Tue, 11 Feb 2020 10:51:54 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     Anton Ivanov <anton.ivanov@...bridgegreys.com>,
        netdev@...r.kernel.org
Cc:     linux-um@...ts.infradead.org, mst@...hat.com,
        virtualization@...ts.linux-foundation.org
Subject: Re: [PATCH] virtio: Work around frames incorrectly marked as gso


On 2020/2/11 上午12:55, Anton Ivanov wrote:
>
>
> On 09/12/2019 10:48, anton.ivanov@...bridgegreys.com wrote:
>> From: Anton Ivanov <anton.ivanov@...bridgegreys.com>
>>
>> Some of the frames marked as GSO which arrive at
>> virtio_net_hdr_from_skb() have no GSO_TYPE, no
>> fragments (data_len = 0) and length significantly shorter
>> than the MTU (752 in my experiments).
>>
>> This is observed on raw sockets reading off vEth interfaces
>> in all 4.x and 5.x kernels I tested.
>>
>> These frames are reported as invalid while they are in fact
>> gso-less frames.
>>
>> This patch marks the vnet header as no-GSO for them instead
>> of reporting it as invalid.
>>
>> Signed-off-by: Anton Ivanov <anton.ivanov@...bridgegreys.com>
>> ---
>>   include/linux/virtio_net.h | 8 ++++++--
>>   1 file changed, 6 insertions(+), 2 deletions(-)
>>
>> diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h
>> index 0d1fe9297ac6..d90d5cff1b9a 100644
>> --- a/include/linux/virtio_net.h
>> +++ b/include/linux/virtio_net.h
>> @@ -112,8 +112,12 @@ static inline int virtio_net_hdr_from_skb(const 
>> struct sk_buff *skb,
>>               hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
>>           else if (sinfo->gso_type & SKB_GSO_TCPV6)
>>               hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
>> -        else
>> -            return -EINVAL;
>> +        else {
>> +            if (skb->data_len == 0)
>> +                hdr->gso_type = VIRTIO_NET_HDR_GSO_NONE;
>> +            else
>> +                return -EINVAL;
>> +        }
>>           if (sinfo->gso_type & SKB_GSO_TCP_ECN)
>>               hdr->gso_type |= VIRTIO_NET_HDR_GSO_ECN;
>>       } else
>>
>
> ping.
>

Do you mean gso_size is set but gso_type is not? Looks like a bug elsewhere.

Thanks