Subject: Re: [PATCH net] net/sched: act_ct: fix restore the qdisc_skb_cb after defrag

From: Florian Westphal <[email-masked]>
Date: Sat, 18 Jul 2020 14:30:06 +0200

[email-masked] <[email-masked]> wrote:
> From: wenxu <[email-masked]>
> 
> The fragment packets do defrag in tcf_ct_handle_fragments
> will clear the skb->cb which make the qdisc_skb_cb clear
> too. So the qdsic_skb_cb should be store before defrag and
> restore after that.
> It also update the pkt_len after all the
> fragments finish the defrag to one packet and make the
> following actions counter correct.
> 
> Fixes: b57dc7c13ea9 ("net/sched: Introduce action ct")
> Signed-off-by: wenxu <[email-masked]>

Looks ok to me.  One question:

> @@ -1014,6 +1017,7 @@ static int tcf_ct_act(struct sk_buff *skb, const struct tc_action *a,
>  
>  out:
>  	tcf_action_update_bstats(&c->common, skb);
> +	qdisc_skb_cb(skb)->pkt_len = skb->len;
>  	return retval;

This appears to be unconditional, I would have expected that
this only done for reassembled skbs?

Otherwise we will lose the value calculated by core via
qdisc_calculate_pkt_len().