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From: Jamal Hadi Salim <jhs@mojatatu.com>
To: "David Ahern" <dsahern@gmail.com>,
	"Asbjørn Sloth Tønnesen" <asbjorn@asbjorn.st>,
	netdev@vger.kernel.org, "Cong Wang" <xiyou.wangcong@gmail.com>
Cc: Stephen Hemminger <stephen@networkplumber.org>,
	Jiri Pirko <jiri@nvidia.com>
Subject: Re: [PATCH iproute2 v3 2/2] tc: pedit: add decrement operation
Date: Thu, 24 Jun 2021 16:24:17 -0400	[thread overview]
Message-ID: <74b620dd-3552-b20d-ba5c-b681e7eabca7@mojatatu.com> (raw)
In-Reply-To: <7b5d610b-0fd6-d466-cd6d-bb2725397cdd@gmail.com>

Hi Asbjørn,


On 2021-06-22 11:39 a.m., David Ahern wrote:
> [ looks fine to me; adding tc folks to make sure they see it ]
> 
> On 6/18/21 10:06 AM, Asbjørn Sloth Tønnesen wrote:
>> Implement a decrement operation for ttl and hoplimit.
>>
>> Since this is just syntactic sugar, it goes that:
>>
>>    tc filter add ... action pedit ex munge ip ttl dec ...
>>    tc filter add ... action pedit ex munge ip6 hoplimit dec ...
>>
>> is just a more readable version of this:
>>
>>    tc filter add ... action pedit ex munge ip ttl add 0xff ...
>>    tc filter add ... action pedit ex munge ip6 hoplimit add 0xff ...
>>

So you "add" essentially one's complement of the value you are trying to
decrement with?

>> This feature was suggested by some pseudo tc examples in Mellanox's
>> documentation[1], but wasn't present in neither their mlnx-iproute2
>> nor iproute2.
>>
>> Tested with skip_sw on Mellanox ConnectX-6 Dx.
>>
>> [1] https://docs.mellanox.com/pages/viewpage.action?pageId=47033989


I didnt see an example which showed using "dec" but what you described
above makes sense. And the changes below look sane. So:

Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>

cheers,
jamal

  reply	other threads:[~2021-06-24 20:24 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-18 16:06 [PATCH iproute2 1/2] tc: pedit: parse_cmd: add flags argument Asbjørn Sloth Tønnesen
2021-06-18 16:06 ` [PATCH iproute2 v3 2/2] tc: pedit: add decrement operation Asbjørn Sloth Tønnesen
2021-06-22 15:39   ` David Ahern
2021-06-24 20:24     ` Jamal Hadi Salim [this message]
2021-06-25 19:21       ` Asbjørn Sloth Tønnesen
2021-06-26  4:45   ` David Ahern

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