netdev - Re: [PATCH net-next v4 2/3] flow_offload: Support get default block from tc immediately

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Date:   Tue, 30 Jul 2019 08:10:03 +0800
From:   wenxu <wenxu@...oud.cn>
To:     Jakub Kicinski <jakub.kicinski@...ronome.com>
Cc:     pablo@...filter.org, fw@...len.de, netfilter-devel@...r.kernel.org,
        netdev@...r.kernel.org
Subject: Re: [PATCH net-next v4 2/3] flow_offload: Support get default block
 from tc immediately


在 2019/7/30 0:55, Jakub Kicinski 写道:
> On Mon, 29 Jul 2019 15:18:03 +0800, wenxu wrote:
>> On 7/29/2019 12:42 PM, Jakub Kicinski wrote:
>>> On Mon, 29 Jul 2019 10:43:56 +0800, wenxu wrote:  
>>>> On 7/29/2019 4:16 AM, Jakub Kicinski wrote:  
>>>>> I don't know the nft code, but it seems unlikely it wouldn't have the
>>>>> same problem/need..    
>>>> nft don't have the same problem.  The offload rule can only attached
>>>> to offload base chain.
>>>>
>>>> Th  offload base chain is created after the device driver loaded (the
>>>> device exist).  
>>> For indirect blocks the block is on the tunnel device and the offload
>>> target is another device. E.g. you offload rules from a VXLAN device
>>> onto the ASIC. The ASICs driver does not have to be loaded when VXLAN
>>> device is created.
>>>
>>> So I feel like either the chain somehow directly references the offload
>>> target (in which case the indirect infrastructure with hash lookup etc
>>> is not needed for nft), or indirect infra is needed, and we need to take
>>> care of replays.  
>> I think the nft is different with tc. 
>>
>> In tc case we can create vxlan device add a ingress qdisc with a block success
>>
>> Then the ASIC driver loaded,  then register the vxlan indr-dev and get the block
>> adn replay it to hardware
>>
>> But in the nft case,  The base chain flags with offload. Create an offload netdev
>> base chain on vxlan device will fail if there is no indr-device to offload.
> Can you show us the offload chain spec? Does it specify offload to the
> vxlan device or the ASIC device?

nft add chain netdev firewall aclout { type filter hook ingress offload device vxlan0 priority - 300 \; }

>
> Indir-devs can come and go, how do you handle a situation where offload
> chain was installed with indir listener present, but then the ASIC
> driver got removed?

yes, I think nft is also need to get the default block in the indr-regster-cb

for the go aways and reload again case

>