netdev - Re: [RFC net-next 2/9] net: bridge: Disambiguate offload_fwd

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Date:   Sun, 2 May 2021 18:00:33 +0300
From:   Ido Schimmel <idosch@...sch.org>
To:     Tobias Waldekranz <tobias@...dekranz.com>
Cc:     davem@...emloft.net, kuba@...nel.org, andrew@...n.ch,
        vivien.didelot@...il.com, f.fainelli@...il.com, olteanv@...il.com,
        roopa@...dia.com, nikolay@...dia.com, jiri@...nulli.us,
        stephen@...workplumber.org, netdev@...r.kernel.org,
        bridge@...ts.linux-foundation.org
Subject: Re: [RFC net-next 2/9] net: bridge: Disambiguate offload_fwd_mark

On Mon, Apr 26, 2021 at 07:04:04PM +0200, Tobias Waldekranz wrote:
> - skb->cb->offload_fwd_mark becomes skb->cb->src_hwdom. There is a
>   slight change here: Whereas previously this was only set for
>   offloaded packets, we now always track the incoming hwdom. As all
>   uses where already gated behind checks of skb->offload_fwd_mark,
>   this will not introduce any functional change, but it paves the way
>   for future changes where the ingressing hwdom must be known both for
>   offloaded and non-offloaded frames.

[...]

> @@ -43,15 +43,15 @@ int nbp_switchdev_mark_set(struct net_bridge_port *p)
>  void nbp_switchdev_frame_mark(const struct net_bridge_port *p,
>  			      struct sk_buff *skb)
>  {
> -	if (skb->offload_fwd_mark && !WARN_ON_ONCE(!p->offload_fwd_mark))
> -		BR_INPUT_SKB_CB(skb)->offload_fwd_mark = p->offload_fwd_mark;
> +	if (p->hwdom)
> +		BR_INPUT_SKB_CB(skb)->src_hwdom = p->hwdom;
>  }

I assume you are referring to this change? "src_hwdom" sounds weird if
it's expected to be valid for non-offloaded frames.

Can you elaborate about "future changes where the ingressing hwdom must
be known both for offloaded and non-offloaded frames"?

Probably best to split this change to a different patch given the rest
of the changes are mechanical.

>  
>  bool nbp_switchdev_allowed_egress(const struct net_bridge_port *p,
>  				  const struct sk_buff *skb)
>  {
>  	return !skb->offload_fwd_mark ||
> -	       BR_INPUT_SKB_CB(skb)->offload_fwd_mark != p->offload_fwd_mark;
> +	       BR_INPUT_SKB_CB(skb)->src_hwdom != p->hwdom;
>  }
>  
>  /* Flags that can be offloaded to hardware */
> -- 
> 2.25.1
>