NACK: [SRU][F:linux-bluefield][PATCH] UBUNTU: SAUCE: net/sched: Increase support of reclassification to 10

[Roi Dayan]

On 2021-05-07 4:53 PM, Daniel Jurgens wrote:
>> From: Tim Gardner <tim.gardner at canonical.com>
>> Sent: Friday, May 7, 2021 7:58 AM
>>
>> I hate to be nit picky, but the subject line reclassify loop limit doesn't match
>> the value in the patch.
> 
> My mistake there. We initially set the value to 10, but then updated it, and I missed updating the title when I squashed the fixup.
> 
>>
>> What kind of performance impact will this incur ? Are unclassifiable packets
>> common ?
> 
> Roi, can you answer this?
> 

Hi,

For the general case there is no performance impact.
This limit protects against accidental loop in tc rules with goto chains
actions. so the only performance impact will only be for the case you
actually have rules with many chains and gotos to jump between the
chains and only for packets that will actually match the tc rules and
do the actions.
i.e.

chain 0: match A goto chain 1
chain 1: match B goto chain 2
chain 2: match C goto chain 3
etc

This is not common but some customers doing connection tracking
rules and changing ct zones could use more than the default.

Thanks,
Roi

>>
>> On 5/5/21 10:43 AM, Daniel Jurgens wrote:
>>> From: Roi Dayan <roid at nvidia.com>
>>>
>>> BugLink: https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fbugs.launchpad.net%2Fbugs%2F1927257&data=04%7C01%7Croid%40nvidia.com%7Cfb101bde402a456f8f6b08d9115f800d%7C43083d15727340c1b7db39efd9ccc17a%7C0%7C0%7C637559924127140735%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=SPKlsmNeNxi%2BA79xVy41Tl8rdk0dDJjIR6O6BdJORBQ%3D&reserved=0
>>>
>>> To support packet reclassification of more than 4 chains increase
>>> max_reclassify_loop from 4 to 15.
>>>
>>> Change-Id: Ie18c37fb0255a737dc8f1b2fcf10a1163266dde6
>>> Signed-off-by: Roi Dayan <roid at nvidia.com>
>>> Reviewed-by: Oz Shlomo <ozsh at nvidia.com>
>>> Signed-off-by: Daniel Jurgens <danielj at nvidia.com>
>>> ---
>>>    net/sched/cls_api.c | 2 +-
>>>    1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c index
>>> b6e0e15..9c9afc0 100644
>>> --- a/net/sched/cls_api.c
>>> +++ b/net/sched/cls_api.c
>>> @@ -1582,7 +1582,7 @@ static inline int __tcf_classify(struct sk_buff *skb,
>>>    				 u32 *last_executed_chain)
>>>    {
>>>    #ifdef CONFIG_NET_CLS_ACT
>>> -	const int max_reclassify_loop = 4;
>>> +	const int max_reclassify_loop = 15;
>>>    	const struct tcf_proto *first_tp;
>>>    	int limit = 0;
>>>
>>>
>>
>> --
>> -----------
>> Tim Gardner
>> Canonical, Inc