From: Alexey Kodanev <alexey.koda...@oracle.com>
Date: Wed, 20 Dec 2017 19:36:03 +0300
> When ip6gre is created using ioctl, its features, such as
> scatter-gather, GSO and tx-checksumming will be turned off:
>
> # ip -f inet6 tunnel add gre6 mode ip6gre remote fd00::1
> # ethtool -k gre6 (truncated output)
> tx-checksumming: off
> scatter-gather: off
> tcp-segmentation-offload: off
> generic-segmentation-offload: off [requested on]
>
> But when netlink is used, they will be enabled:
> # ip link add gre6 type ip6gre remote fd00::1
> # ethtool -k gre6 (truncated output)
> tx-checksumming: on
> scatter-gather: on
> tcp-segmentation-offload: on
> generic-segmentation-offload: on
>
> This results in a loss of performance when gre6 is created via ioctl.
> The issue was found with LTP/gre tests.
>
> Fix it by moving the setup of device features to a separate function
> and invoke it with ndo_init callback because both netlink and ioctl
> will eventually call it via register_netdevice():
>
> register_netdevice()
> - ndo_init() callback -> ip6gre_tunnel_init() or ip6gre_tap_init()
> - ip6gre_tunnel_init_common()
> - ip6gre_tnl_init_features()
>
> The moved code also contains two minor style fixes:
> * removed needless tab from GRE6_FEATURES on NETIF_F_HIGHDMA line.
> * fixed the issue reported by checkpatch: "Unnecessary parentheses around
> 'nt->encap.type == TUNNEL_ENCAP_NONE'"
>
> Fixes: ac4eb009e477 ("ip6gre: Add support for basic offloads offloads
> excluding GSO")
> Signed-off-by: Alexey Kodanev <alexey.koda...@oracle.com>
Looks good, applied and queued up for -stable.
