netdev - Re: WAS ( Re: [PATCH net-next 1/1] net

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Message-ID: <5790DF60.5010900@iogearbox.net>
Date:	Thu, 21 Jul 2016 16:42:40 +0200
From:	Daniel Borkmann <daniel@...earbox.net>
To:	Jamal Hadi Salim <jhs@...atatu.com>,
	Cong Wang <xiyou.wangcong@...il.com>
CC:	Alexei Starovoitov <alexei.starovoitov@...il.com>,
	David Miller <davem@...emloft.net>,
	Linux Kernel Network Developers <netdev@...r.kernel.org>,
	Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
Subject: Re: WAS ( Re: [PATCH net-next 1/1] net_sched: Introduce skbmod action

On 07/21/2016 09:27 AM, Jamal Hadi Salim wrote:
[...]
> Forgot about csum which would work with pedit - didnt quiet parse what
> you are saying above though:
> does changing MAC address require changing to CHECKSUM_NONE? If yes,
> then seems like i need to send a patch for act_ife as well to make in
> the spirit of mirred?

Hmm, seems fine actually up to ETH_HLEN. In cases like vlan or mpls
modifications there's certainly a correction, but when going into rx
path this is pulled out already of the calculation afaik (see f.e.
dev_forward_skb()). So when mirred pushes this back in via skb_push_rcsum()
and dev_forward_skb() back out, it should be okay if I see this correctly.
But don't you still something like need skb_try_make_writable()?