[ovs-dev] [PATCH v7] datapath: Add Stateless TCP Tunneling protocol.

Pravin Shelar pshelar at nicira.com
Wed Apr 22 17:03:04 UTC 2015


On Mon, Apr 20, 2015 at 9:54 PM, Jesse Gross <jesse at nicira.com> wrote:
> On Mon, Apr 20, 2015 at 7:33 PM, Pravin Shelar <pshelar at nicira.com> wrote:
>> On Mon, Apr 20, 2015 at 5:56 PM, Jesse Gross <jesse at nicira.com> wrote:
>>> On Mon, Apr 20, 2015 at 3:54 PM, Pravin Shelar <pshelar at nicira.com> wrote:
>>>> On Mon, Apr 20, 2015 at 3:36 PM, Jesse Gross <jesse at nicira.com> wrote:
>>>>> On Mon, Apr 20, 2015 at 1:29 PM, Pravin B Shelar <pshelar at nicira.com> wrote:
>>>>>> diff --git a/datapath/linux/compat/stt.c b/datapath/linux/compat/stt.c
>>>>>> new file mode 100644
>>>>>> index 0000000..209bf1a
>>>>>> --- /dev/null
>>>>>> +++ b/datapath/linux/compat/stt.c
>>>>>> +static void update_headers(struct sk_buff *skb, bool head,
>>>>>> +                              unsigned int l4_offset, unsigned int hdr_len,
>>>>>> +                              bool ipv4, u32 tcp_seq)
>>>>> [...]
>>>>>> +       skb->truesize = SKB_TRUESIZE(skb_end_offset(skb)) + skb->data_len;
>>>>>> +}
>>>>>
>>>>> I wonder if there are any possible edge cases with resetting truesize
>>>>> where the packet is still in someone's transmit queue (such as if we
>>>>> are looping back packet). Do we need to orphan it first?
>>>>>
>>>> ok, I will orphan it in update_headers.
>>>
>>> Just to clarify - I was mostly just thinking aloud on orphaning it.
>>> I'm not totally sure if that is the right thing to do or if this is
>>> the right place to do it. I'm not sure what the conceptual
>>> justification would be for it and it could potentially result in the
>>> sender's buffers not being properly limited. Perhaps not resetting the
>>> truesize is the right thing too...
>>>
>> I have seen warning msg if we do no keep truesize update along with
>> changes to skb.
>
> Hmm, interesting, what is the warning? I don't think that I have seen
> that before.

Actually skb_try_coalesce() is updating it correctly. so there no need
to change truesize anymore. I will update patch accordingly.



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