netdev - Re: [PATCH net 2/2] net/sched: act_ct: Set offload timeout when setting the offload bit

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Date:   Mon, 3 Aug 2020 10:21:21 +0300
From:   Roi Dayan <roid@...lanox.com>
To:     Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
Cc:     netdev@...r.kernel.org, pablo@...filter.org,
        Paul Blakey <paulb@...lanox.com>, Oz Shlomo <ozsh@...lanox.com>
Subject: Re: [PATCH net 2/2] net/sched: act_ct: Set offload timeout when
 setting the offload bit



On 2020-07-29 8:10 PM, Marcelo Ricardo Leitner wrote:
> On Wed, Jul 29, 2020 at 03:55:53PM +0300, Roi Dayan wrote:
>>
>>
>> On 2020-07-28 5:42 PM, Marcelo Ricardo Leitner wrote:
>>> On Tue, Jul 28, 2020 at 02:57:59PM +0300, Roi Dayan wrote:
>>>> On heavily loaded systems the GC can take time to go over all existing
>>>> conns and reset their timeout. At that time other calls like from
>>>> nf_conntrack_in() can call of nf_ct_is_expired() and see the conn as
>>>> expired. To fix this when we set the offload bit we should also reset
>>>> the timeout instead of counting on GC to finish first iteration over
>>>> all conns before the initial timeout.
>>>>
>>>> Fixes: 64ff70b80fd4 ("net/sched: act_ct: Offload established connections to flow table")
>>>> Signed-off-by: Roi Dayan <roid@...lanox.com>
>>>> Reviewed-by: Oz Shlomo <ozsh@...lanox.com>
>>>> ---
>>>>  net/sched/act_ct.c | 2 ++
>>>>  1 file changed, 2 insertions(+)
>>>>
>>>> diff --git a/net/sched/act_ct.c b/net/sched/act_ct.c
>>>> index e9f3576cbf71..650c2d78a346 100644
>>>> --- a/net/sched/act_ct.c
>>>> +++ b/net/sched/act_ct.c
>>>> @@ -366,6 +366,8 @@ static void tcf_ct_flow_table_add(struct tcf_ct_flow_table *ct_ft,
>>>
>>> Extra context line:
>>> 	err = flow_offload_add(&ct_ft->nf_ft, entry);
>>>>  	if (err)
>>>>  		goto err_add;
>>>>  
>>>> +	nf_ct_offload_timeout(ct);
>>>> +
>>>
>>> What about adding this to flow_offload_add() instead?
>>> It is already adjusting the flow_offload timeout there and then it
>>> also effective for nft.
>>>
>>
>> As you said, in flow_offload_add() we adjust the flow timeout.
>> Here we adjust the conn timeout.
>> So it's outside flow_offload_add() which only touch the flow struct.
>> I guess it's like conn offload bit is set outside here and for nft.
> 
> Right, but
> 
>> What do you think?
> 
> I don't see why it can't update both. flow_offload_fixup_ct_timeout(),
> called by flow_offload_del(), is updating ct->timeout already. It
> looks consistent to me to update it in _add as well then. 
> 

I don't mind. just add is not consistent with del.
del also clears the ips_offload_bit but add doesn't add it.
i'll send v2 with your suggestion.

>>
>>>>  	return;
>>>>  
>>>>  err_add:
>>>> -- 
>>>> 2.8.4
>>>>