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

On Wed, Nov 25, 2020 at 09:34:29PM +0100, Andrew Lunn wrote:

quoted

+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.

quoted

+	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.