Re: [PATCH net-next v2 1/3] dsa: add support for Arrow XRS700x tag trailer

[Vladimir Oltean <olteanv@gmail.com>]

On Wed, Nov 25, 2020 at 09:34:29PM +0100, Andrew Lunn wrote:
> > +static struct sk_buff *xrs700x_rcv(struct sk_buff *skb, struct net_device *dev,
> > +				   struct packet_type *pt)
> > +{
> > +	int source_port;
> > +	u8 *trailer;
> > +
> > +	if (skb_linearize(skb))
> > +		return NULL;
>
> Something for Vladimir:
>
> Could this linearise be moved into the core, depending on the
> tail_tag?

Honestly I believe that the skb_linearize is not needed at all. It is
copy-pasted from tag_trailer.c, a driver that has not exercised at
runtime by anybody for a long time now. The pskb_trim_rcsum function
used for removing the tail tag should do the right thing even with
fragmented packets.

> > +	if (pskb_trim_rcsum(skb, skb->len - 1))
> > +		return NULL;
>
> And the overhead is also in dsa_devlink_ops, so maybe this can be
> moved as well?

Sorry, I don't understand this comment.