Re: [PATCH net-next] gso: enable udp gso for virtual devices

[Willem de Bruijn <willemdebruijn.kernel@gmail.com>]

On Fri, Aug 9, 2019 at 2:58 PM Josh Hunt <johunt@akamai.com> wrote:
>
> On 6/26/19 4:41 PM, Willem de Bruijn wrote:
> > On Wed, Jun 26, 2019 at 3:17 PM Jason Baron <jbaron@akamai.com> wrote:
> >>
> >>
> >>
> >> On 6/14/19 4:53 PM, Jason Baron wrote:
> >>>
> >>>
> >>> On 6/13/19 5:20 PM, Willem de Bruijn wrote:
> >>>>>>> @@ -237,6 +237,7 @@ static inline int find_next_netdev_feature(u64 feature, unsigned long start)
> >>>>>>>                                   NETIF_F_GSO_GRE_CSUM |                 \
> >>>>>>>                                   NETIF_F_GSO_IPXIP4 |                   \
> >>>>>>>                                   NETIF_F_GSO_IPXIP6 |                   \
> >>>>>>> +                                NETIF_F_GSO_UDP_L4 |                   \
> >>>>>>>                                   NETIF_F_GSO_UDP_TUNNEL |               \
> >>>>>>>                                   NETIF_F_GSO_UDP_TUNNEL_CSUM)
> >>>>>>
> >>>>>> Are you adding this to NETIF_F_GSO_ENCAP_ALL? Wouldn't it make more
> >>>>>> sense to add it to NETIF_F_GSO_SOFTWARE?
> >>>>>>
> >>>>>
> >>>>> Yes, I'm adding to NETIF_F_GSO_ENCAP_ALL (not very clear from the
> >>>>> context). I will fix the commit log.
> >>>>>
> >>>>> In: 83aa025 udp: add gso support to virtual devices, the support was
> >>>>> also added to NETIF_F_GSO_ENCAP_ALL (although subsequently reverted due
> >>>>> to UDP GRO not being in place), so I wonder what the reason was for that?
> >>>>
> >>>> That was probably just a bad choice on my part.
> >>>>
> >>>> It worked in practice, but if NETIF_F_GSO_SOFTWARE works the same
> >>>> without unexpected side effects, then I agree that it is the better choice.
> >>>>
> >>>> That choice does appear to change behavior when sending over tunnel
> >>>> devices. Might it send tunneled GSO packets over loopback?
> >>>>
> >>>>
> >>>
> >>> I set up a test case using fou tunneling through a bridge device using
> >>> the udpgso_bench_tx test where packets are not received correctly if
> >>> NETIF_F_GSO_UDP_L4 is added to NETIF_F_GSO_SOFTWARE. If I have it added
> >>> to NETIF_F_GSO_ENCAP_ALL, it does work correctly. So there are more
> >>> fixes required to include it in NETIF_F_GSO_SOFTWARE.
> >>>
> >>> The use-case I have only requires it to be in NETIF_F_GSO_ENCAP_ALL, but
> >>> if it needs to go in NETIF_F_GSO_SOFTWARE, I can look at what's required
> >>> more next week.
> >>>
> >>
> >> Hi,
> >>
> >> I haven't had a chance to investigate what goes wrong with including
> >> NETIF_F_GSO_UDP_L4 in NETIF_F_GSO_SOFTWARE - but I was just wondering if
> >> people are ok with NETIF_F_GSO_UDP_L4 being added to
> >> NETIF_F_GSO_ENCAP_ALL and not NETIF_F_GSO_SOFTWARE (ie the original
> >> patch as posted)?
> >>
> >> As I mentioned that is sufficient for my use-case, and its how Willem
> >> originally proposed this.
> >
> > Indeed, based on the previous discussion this sounds fine to me.
> >
>
> Willem
>
> Are you OK to ACK this? If not, is there something else you'd rather see
> here?

Sure. Unless Alex still has objections, feel free to resubmit with my Acked-by.