Re: [PATCH net-next v2 2/2] bnxt_en: Pad short SW USO segments to BNXT_MIN_PKT_SIZE

[Joe Damato]

On Fri, Oct 09, 2026 at 02:54:24PM -0700, Joe Damato wrote:
> Each SW USO segment is hdr_len + seg_payload bytes. With IPv4, hdr_len
> is 42 bytes, so a segment carrying less than 10 bytes of UDP payload is
> sent shorter than BNXT_MIN_PKT_SIZE. This happens with a short last
> segment (e.g. gso_size 1400 and 1405 bytes of payload) or with a
> gso_size below 10 bytes.

[...]

> diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt_gso.c b/drivers/net/ethernet/broadcom/bnxt/bnxt_gso.c
> index ef04c9d08066..80d5c4f963a9 100644
> --- a/drivers/net/ethernet/broadcom/bnxt/bnxt_gso.c
> +++ b/drivers/net/ethernet/broadcom/bnxt/bnxt_gso.c
> @@ -82,11 +82,19 @@ int bnxt_sw_udp_gso_xmit(struct bnxt *bp, struct bnxt_tx_ring_info *txr,
>  	if (unlikely(num_segs <= 1))
>  		goto drop;
>  
> +	/* bnxt_features_check() makes the stack segment these, but paths
> +	 * that skip validate_xmit_skb() (e.g. generic XDP_TX of a GRO'd
> +	 * skb) can still get here. Padding every segment would need more
> +	 * BDs than bds_needed reserves below, so drop instead.
> +	 */
> +	if (unlikely(bnxt_sw_gso_pad_len(hdr_len, mss)))
> +		goto drop;
> +

I could be wrong, but I think if [1] is applied this drop can go away (?)

[1]: https://lore.kernel.org/netdev/20260928223648.2739371-6-kuba@xxxxxxxxxx/