[ovs-dev] [PATCH v2 19/24] datapath: backport: udp_offload: Set encapsulation before inner completes.

[pravin shelar]

On Tue, Jul 5, 2016 at 12:07 PM, Jesse Gross <jesse at kernel.org> wrote:
> I guess it's not applicable in the sense that the fix is not really in
> OVS. Kernels with that bug will continue to have it even after this
> backport.
>
> I think it would be pretty challenging to fully backport this through
> the OVS tree - it would likely require pulling in the whole UDP
> offloads module. That would pretty messy and would silently prevent
> other non-OVS users from taking advantage of offloads. To the extent
> that this affects OVS users, I think probably needs to be picked up by
> distribution kernels.
>

Loadable module can not change kernel udp_gro_complete(), so I can not
backport it into OVS.
Anyways setting inner mac header is still improvement, if
distributions back port whole commit.

> On Mon, Jul 4, 2016 at 4:02 AM, Jarno Rajahalme <jarno at ovn.org> wrote:
>> I'm not really familiar with these backports, but is it so that the main change the upstream patch introduced to udp_gro_complete() is not applicable to the backports?
>>
>>   Jarno
>>
>>> On Jun 30, 2016, at 1:06 AM, Pravin B Shelar <pshelar at ovn.org> wrote:
>>>
>>> Upstream commit:
>>>    commit 229740c63169462a838a8b8e16391ed000934631
>>>    Author: Jarno Rajahalme <jarno at ovn.org>
>>>
>>>    udp_offload: Set encapsulation before inner completes.
>>>
>>>    UDP tunnel segmentation code relies on the inner offsets being set for
>>>    an UDP tunnel GSO packet, but the inner *_complete() functions will
>>>    set the inner offsets only if 'encapsulation' is set before calling
>>>    them.  Currently, udp_gro_complete() sets 'encapsulation' only after
>>>    the inner *_complete() functions are done.  This causes the inner
>>>    offsets having invalid values after udp_gro_complete() returns, which
>>>    in turn will make it impossible to properly segment the packet in case
>>>    it needs to be forwarded, which would be visible to the user either as
>>>    invalid packets being sent or as packet loss.
>>>
>>>    This patch fixes this by setting skb's 'encapsulation' in
>>>    udp_gro_complete() before calling into the inner complete functions,
>>>    and by making each possible UDP tunnel gro_complete() callback set the
>>>    inner_mac_header to the beginning of the tunnel payload.
>>>
>>>    Signed-off-by: Jarno Rajahalme <jarno at ovn.org>
>>>    Reviewed-by: Alexander Duyck <aduyck at mirantis.com>
>>>    Signed-off-by: David S. Miller <davem at davemloft.net>
>>>
>>> Signed-off-by: Pravin B Shelar <pshelar at ovn.org>
>>> ---
>>> datapath/linux/compat/geneve.c | 2 ++
>>> 1 file changed, 2 insertions(+)
>>>
>>> diff --git a/datapath/linux/compat/geneve.c b/datapath/linux/compat/geneve.c
>>> index e049221..cc8740b 100644
>>> --- a/datapath/linux/compat/geneve.c
>>> +++ b/datapath/linux/compat/geneve.c
>>> @@ -566,6 +566,8 @@ static int geneve_gro_complete(struct sk_buff *skb, int nhoff,
>>>               err = ptype->callbacks.gro_complete(skb, nhoff + gh_len);
>>>
>>>       rcu_read_unlock();
>>> +
>>> +     skb_set_inner_mac_header(skb, nhoff + gh_len);
>>>       return err;
>>> }
>>> #endif
>>> --
>>> 1.9.1
>>>
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