Subject: Re: [PATCH v3 net-next 1/1] net_sched: Introduce skbmod action

From: Daniel Borkmann <[email-masked]>
Date: Mon, 29 Aug 2016 13:00:59 +0200

On 08/29/2016 12:38 PM, Jamal Hadi Salim wrote:
> On 16-08-28 12:07 PM, Eric Dumazet wrote:
>
>> Adding an action with a spinlock held in fast path in 2016 is
>> a way to tell people : It is a toy, do not use it for real.
>>
>> Sorry guys. Friends do not let friends do that anymore.
>
> Generally agree.
> Cong says he is working on generic patches. Let me see if i can
> try something. Trickery with RCU is not one of my virtues -
> so i may get it wrong but hope you can comment.

You could probably just keep these meta data in a separate struct
managed by RCU that tcf_skbmod points to.

One more thing I commented on your last patch already is that you
would also need f.e. skb_ensure_writable() before mangling.