Re: [PATCH net-next v4] ppp: enable TX scatter-gather

Paolo Abeni
2026-02-03T16:33:33Z

On 2/3/26 4:08 PM, Qingfang Deng wrote:
> On Tue, Feb 3, 2026 at 6:55 PM Paolo Abeni <pabeni@redhat.com> wrote:
>> I'm sorry for missing this point before, but AFAICS channels with
>> chan->direct_xmit == 0 do not support GSO packets at all, and here such
>> packets will be transmitted after linearization (but still as GSO).
>>
>> I think that while transmitting over !chan->direct_xmit you additionally
>> need to check for GSO packet. If ppp features are recomputed depending
>> on the channels configuration, you could chose to drop such packets.
>> Otherwise you will need to segment them before transmission, and that
>> looks error prone in case of multilink.
>
> I don't think that's true. Using the current features set (NETIF_F_SG
> | NETIF_F_FRAGLIST), the network core will only enable the generic
> software GSO (NETIF_F_GSO), and a GSO skb will be segmented in
> validate_xmit_skb before being passed to the PPP driver.

Right you are! I thought TSO was enabled here at some point but it's not
the case. No need to resubmit, let me resurrect this patch in PW.

Thanks,

Paolo