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

On Mon, 28 Sep 2026 19:47:43 -0400 Willem de Bruijn wrote:

quoted

+	/*
+	 * 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.

quoted

+	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.

quoted

+	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.