netdev - Re: [PATCH net-next v2 2/2] ip_gre: propogate target device GSO capability to the tunnel device

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Message-ID: <1361724339.20403.2.camel@lb-tlvb-dmitry.il.broadcom.com>
Date:	Sun, 24 Feb 2013 18:45:39 +0200
From:	"Dmitry Kravkov" <dmitry@...adcom.com>
To:	pravin <pravin.shelar@...il.com>
cc:	davem@...emloft.net, netdev@...r.kernel.org
Subject: Re: [PATCH net-next v2 2/2] ip_gre: propogate target device GSO
 capability to the tunnel device

On Thu, 2013-02-21 at 15:53 -0800, pravin wrote:
> On Thu, Feb 21, 2013 at 2:30 PM, Dmitry Kravkov <dmitry@...adcom.com> wrote:
> > On Tue, 2013-02-19 at 10:39 -0800, pravin wrote:
> >> On Mon, Feb 18, 2013 at 11:50 AM, Dmitry Kravkov <dmitry@...adcom.com> wrote:
> >> >
> >> > Signed-off-by: Dmitry Kravkov <dmitry@...adcom.com>
> >> > ---
> >> > Changes from v1: fixed email address
> >> >
> >> >
> >> >  net/ipv4/ip_gre.c |   10 ++++++++--
> >> >  1 files changed, 8 insertions(+), 2 deletions(-)
> >> >
> >> > diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
> >> > index cdc31ac..31bc941 100644
> >> > --- a/net/ipv4/ip_gre.c
> >> > +++ b/net/ipv4/ip_gre.c
> >> > @@ -1103,8 +1103,14 @@ static int ipgre_tunnel_bind_dev(struct net_device *dev)
> >> >         tunnel->hlen = addend;
> >> >         /* TCP offload with GRE SEQ is not supported. */
> >> >         if (!(tunnel->parms.o_flags & GRE_SEQ)) {
> >> > -               dev->features           |= NETIF_F_GSO_SOFTWARE;
> >> > -               dev->hw_features        |= NETIF_F_GSO_SOFTWARE;
> >> > +               /* device supports enc gso offload*/
> >> > +               if (tdev->hw_enc_features & NETIF_F_GRE_GSO) {
> >> > +                       dev->features           |= NETIF_F_TSO;
> >> > +                       dev->hw_features        |= NETIF_F_TSO;
> >> > +               } else {
> >> > +                       dev->features           |= NETIF_F_GSO_SOFTWARE;
> >> > +                       dev->hw_features        |= NETIF_F_GSO_SOFTWARE;
> >> > +               }
> >> >         }
> >>
> >> I am not sure about this change, Are you trying to limit GRE TSO to
> >> just IPV4  in case of GRE offload in hardware?
> >
> >
> > This mostly reverts previous patch, but also disables GSO when CSUM is
> > set.
> >
> > ---
> >  net/ipv4/ip_gre.c |   14 ++++----------
> >  1 files changed, 4 insertions(+), 10 deletions(-)
> >
> > diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
> > index 0de54cd..aae2d4b 100644
> > --- a/net/ipv4/ip_gre.c
> > +++ b/net/ipv4/ip_gre.c
> > @@ -1107,16 +1107,10 @@ static int ipgre_tunnel_bind_dev(struct
> > net_device *dev)
> >                 mtu = 68;
> >
> >         tunnel->hlen = addend;
> > -       /* TCP offload with GRE SEQ is not supported. */
> > -       if (!(tunnel->parms.o_flags & GRE_SEQ)) {
> > -               /* device supports enc gso offload*/
> > -               if (tdev->hw_enc_features & NETIF_F_GRE_GSO) {
> > -                       dev->features           |= NETIF_F_TSO;
> > -                       dev->hw_features        |= NETIF_F_TSO;
> > -               } else {
> > -                       dev->features           |= NETIF_F_GSO_SOFTWARE;
> > -                       dev->hw_features        |= NETIF_F_GSO_SOFTWARE;
> > -               }
> > +       /* TCP offload with GRE SEQ or CSUM is not supported. */
> > +       if (!(tunnel->parms.o_flags & (GRE_SEQ|GRE_CSUM))) {
> > +               dev->features           |= NETIF_F_GSO_SOFTWARE;
> > +               dev->hw_features        |= NETIF_F_GSO_SOFTWARE;
> >         }
> >
> >         return mtu;
> 
> This narrows down definition of NETIF_F_GRE_GSO. Is it required for
> hardware offload?

This is required to prevent dev_hard_xmit() to perform soft GSO.
W/o it device receives divided packets.




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