[net-next,2/3] gso: limit udp gso to egress-only virtual devices

From: Willem de Bruijn <willemb@google.com>

Until the udp receive stack supports large packets (UDP GRO), GSO
packets must not loop from the egress to the ingress path.

Revert the change that added NETIF_F_GSO_UDP_L4 to various virtual
devices through NETIF_F_GSO_ENCAP_ALL as this included devices that
may loop packets, such as veth and macvlan.

Instead add it to specific devices that forward to another device's
egress path: bonding and team.

Fixes: 83aa025f535f ("udp: add gso support to virtual devices")
CC: Alexander Duyck <alexander.duyck@gmail.com>
Signed-off-by: Willem de Bruijn <willemb@google.com>
---
 drivers/net/bonding/bond_main.c | 5 +++--
 drivers/net/team/team.c         | 5 +++--
 include/linux/netdev_features.h | 1 -
 3 files changed, 6 insertions(+), 5 deletions(-)

On Mon, May 14, 2018 at 7:07 PM, Willem de Bruijn
<willemdebruijn.kernel@gmail.com> wrote:
> From: Willem de Bruijn <willemb@google.com>
>
> Until the udp receive stack supports large packets (UDP GRO), GSO
> packets must not loop from the egress to the ingress path.
>
> Revert the change that added NETIF_F_GSO_UDP_L4 to various virtual
> devices through NETIF_F_GSO_ENCAP_ALL as this included devices that
> may loop packets, such as veth and macvlan.
>
> Instead add it to specific devices that forward to another device's
> egress path: bonding and team.
>
> Fixes: 83aa025f535f ("udp: add gso support to virtual devices")
> CC: Alexander Duyck <alexander.duyck@gmail.com>
> Signed-off-by: Willem de Bruijn <willemb@google.com>
> ---

> diff --git a/drivers/net/team/team.c b/drivers/net/team/team.c
> index 9dbd390ace34..c6a9f0cafea2 100644
> --- a/drivers/net/team/team.c
> +++ b/drivers/net/team/team.c
> @@ -1026,7 +1026,8 @@ static void __team_compute_features(struct team *team)
>         }
>
>         team->dev->vlan_features = vlan_features;
> -       team->dev->hw_enc_features = enc_features | NETIF_F_GSO_ENCAP_ALL;
> +       team->dev->hw_enc_features = enc_features | NETIF_F_GSO_ENCAP_ALL |
> +                                    NETIF_GSO_UDP_L4;

This has a typo. team.ko did not build automatically for me and caught it
with a full compile just too late.

Need to send a v2, sorry.

Hi Willem,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on net-next/master]

url:    https://github.com/0day-ci/linux/commits/Willem-de-Bruijn/udp-gso-fixes/20180515-120246
config: xtensa-allmodconfig (attached as .config)
compiler: xtensa-linux-gcc (GCC) 7.2.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        make.cross ARCH=xtensa 

All errors (new ones prefixed by >>):

   drivers/net//team/team.c: In function '__team_compute_features':
>> drivers/net//team/team.c:1030:10: error: 'NETIF_GSO_UDP_L4' undeclared (first use in this function); did you mean 'NETIF_F_GSO_UDP_L4'?
             NETIF_GSO_UDP_L4;
             ^~~~~~~~~~~~~~~~
             NETIF_F_GSO_UDP_L4
   drivers/net//team/team.c:1030:10: note: each undeclared identifier is reported only once for each function it appears in

vim +1030 drivers/net//team/team.c

   996	
   997	#define TEAM_VLAN_FEATURES (NETIF_F_HW_CSUM | NETIF_F_SG | \
   998				    NETIF_F_FRAGLIST | NETIF_F_ALL_TSO | \
   999				    NETIF_F_HIGHDMA | NETIF_F_LRO)
  1000	
  1001	#define TEAM_ENC_FEATURES	(NETIF_F_HW_CSUM | NETIF_F_SG | \
  1002					 NETIF_F_RXCSUM | NETIF_F_ALL_TSO)
  1003	
  1004	static void __team_compute_features(struct team *team)
  1005	{
  1006		struct team_port *port;
  1007		u32 vlan_features = TEAM_VLAN_FEATURES & NETIF_F_ALL_FOR_ALL;
  1008		netdev_features_t enc_features  = TEAM_ENC_FEATURES;
  1009		unsigned short max_hard_header_len = ETH_HLEN;
  1010		unsigned int dst_release_flag = IFF_XMIT_DST_RELEASE |
  1011						IFF_XMIT_DST_RELEASE_PERM;
  1012	
  1013		list_for_each_entry(port, &team->port_list, list) {
  1014			vlan_features = netdev_increment_features(vlan_features,
  1015						port->dev->vlan_features,
  1016						TEAM_VLAN_FEATURES);
  1017			enc_features =
  1018				netdev_increment_features(enc_features,
  1019							  port->dev->hw_enc_features,
  1020							  TEAM_ENC_FEATURES);
  1021	
  1022	
  1023			dst_release_flag &= port->dev->priv_flags;
  1024			if (port->dev->hard_header_len > max_hard_header_len)
  1025				max_hard_header_len = port->dev->hard_header_len;
  1026		}
  1027	
  1028		team->dev->vlan_features = vlan_features;
  1029		team->dev->hw_enc_features = enc_features | NETIF_F_GSO_ENCAP_ALL |
> 1030					     NETIF_GSO_UDP_L4;
  1031		team->dev->hard_header_len = max_hard_header_len;
  1032	
  1033		team->dev->priv_flags &= ~IFF_XMIT_DST_RELEASE;
  1034		if (dst_release_flag == (IFF_XMIT_DST_RELEASE | IFF_XMIT_DST_RELEASE_PERM))
  1035			team->dev->priv_flags |= IFF_XMIT_DST_RELEASE;
  1036	}
  1037	

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