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From: Cong Wang <xiyou.wangcong@gmail.com>
To: Daniel Borkmann <daniel@iogearbox.net>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>,
	Alexei Starovoitov <alexei.starovoitov@gmail.com>,
	David Miller <davem@davemloft.net>,
	Linux Kernel Network Developers <netdev@vger.kernel.org>,
	Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Subject: Re: [PATCH net-next 1/1] net_sched: Introduce skbmod action
Date: Tue, 19 Jul 2016 11:04:13 -0700	[thread overview]
Message-ID: <CAM_iQpWX5HT_yF3guCbQLMo2GSVGA8BTcJ3_bucHrnBrMQbjqw@mail.gmail.com> (raw)
In-Reply-To: <578E414C.1080501@iogearbox.net>

On Tue, Jul 19, 2016 at 8:03 AM, Daniel Borkmann <daniel@iogearbox.net> wrote:
> On 07/19/2016 03:56 PM, Jamal Hadi Salim wrote:
> [...]
>>>
>>> But apart from this,
>>> neither pedit nor tcf_skbmod_run() here handle checksum complete, so
>>> you'll
>>> potentially get false positives wrt csum corruption and drops as a result
>>> when using either of the two.
>>
>>
>> pedit maybe tricky. Any suggestions?
>> On tcf_skbmod_run, mostly ignorance: while doing only ethernet updates;
>> is it still needed to do the checksum complete?
>
>
> Well, what Cong recently fixed with mirred was related to mac header ...
>
> You probably need skb_postpull_rcsum(), skb_postpush_rcsum() pair.
>
> Also, what about skb_try_make_writable()?

I don't think so. 1) checksum is supposed to be done by csum action
rather than pedit (or skbmod if it matters), 2) csum action currently
already handles that correctly for both egress and ingress: 2a)
CHECKSUM_COMPLETE is meaningless on egress; 2b) it forces
CHECKSUM_COMPLETE to be CHECKSUM_NONE on ingress
and it is correctly respected.

  reply	other threads:[~2016-07-19 18:04 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-07-17  8:41 [PATCH net-next 1/1] net_sched: Introduce skbmod action Jamal Hadi Salim
2016-07-18  4:19 ` Alexei Starovoitov
2016-07-18  6:51   ` Jamal Hadi Salim
2016-07-18  9:44     ` Daniel Borkmann
2016-07-18 10:07       ` Thomas Graf
2016-07-18 10:26         ` Jamal Hadi Salim
2016-07-18 17:38           ` Cong Wang
2016-07-19 10:28             ` Jamal Hadi Salim
2016-07-18 10:08       ` Jamal Hadi Salim
2016-07-19 13:21         ` Daniel Borkmann
2016-07-19 13:56           ` Jamal Hadi Salim
2016-07-19 15:03             ` Daniel Borkmann
2016-07-19 18:04               ` Cong Wang [this message]
2016-07-20  0:23                 ` Daniel Borkmann
2016-07-21  7:27                   ` WAS ( " Jamal Hadi Salim
2016-07-21 14:42                     ` Daniel Borkmann

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