Re: [PATCH net-next v3 4/5] net: core: resegment oversized TCP GSO skbs

[Wang Zhan <wang.zhan@smartx.com>]

On Mon, 28 Sep 2026 19:47:43 -0400 Willem de Bruijn wrote:
> > +	/*
> > +	 * The TCP frag-list path segments through skb_segment_list(), which
> > +	 * does not carry max_segs, so bounded calls skip those skbs.
> > +	 */
>
> This comment answers only one of six conditions. And one that is
> pretty straightforward. I'd drop.
>
> In general, drop all too-obvious comments. AI has a habit of adding
> a lot more, and more low information, comments than is customary in
> kernel code (where we also have commit messages). Generally, repeating
> what the code does is of little value.

Dropped in v4.  I will check all the comments in the series.

> > +	if (!skb_is_gso(skb) || !skb_is_gso_tcp(skb) ||
> > +	    skb->encapsulation || skb_has_frag_list(skb) ||
> > +	    !skb_mac_header_was_set(skb) ||
> > +	    !skb_transport_header_was_set(skb))
>
> Conversely, they last two conditions are less obvious. Are they not
> always true for a TSO packet?

The transport header can be missing.  qdisc_pkt_len_segs_init() does the
same check on this path (net/core/dev.c:4245, a0dce8752193e).

The mac header is always set.  It can be dropped in v4.

> > +	gso_max_size = netif_get_gso_max_size(dev, vlan_get_protocol(skb));
>
> Third time this is now called in validate_xmit_skb. Not sure if that can
> easily be avoided.

Maybe we can pass the oversize and gso_max_size flags out of
__netif_skb_features, but it would be a bit ugly.  I think the current
cost is acceptable.