[PATCH 4.14 081/146] ip6_gre: fix device features for ioctl setup

Greg Kroah-Hartman
2018-01-01T14:43:31Z

From: Alexey Kodanev <alexey.kodanev@oracle.com>

[ Upstream commit e5a9336adb317db55eb3fe8200856096f3c71109 ]

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.kodanev@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/ipv6/ip6_gre.c | 57 +++++++++++++++++++++++++++++------------------------
1 file changed, 32 insertions(+), 25 deletions(-)

--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -1020,6 +1020,36 @@ static void ip6gre_tunnel_setup(struct n
eth_random_addr(dev->perm_addr);
}

+#define GRE6_FEATURES (NETIF_F_SG | \
+ NETIF_F_FRAGLIST | \
+ NETIF_F_HIGHDMA | \
+ NETIF_F_HW_CSUM)
+
+static void ip6gre_tnl_init_features(struct net_device *dev)
+{
+ struct ip6_tnl *nt = netdev_priv(dev);
+
+ dev->features |= GRE6_FEATURES;
+ dev->hw_features |= GRE6_FEATURES;
+
+ if (!(nt->parms.o_flags & TUNNEL_SEQ)) {
+ /* TCP offload with GRE SEQ is not supported, nor
+ * can we support 2 levels of outer headers requiring
+ * an update.
+ */
+ if (!(nt->parms.o_flags & TUNNEL_CSUM) ||
+ nt->encap.type == TUNNEL_ENCAP_NONE) {
+ dev->features |= NETIF_F_GSO_SOFTWARE;
+ dev->hw_features |= NETIF_F_GSO_SOFTWARE;
+ }
+
+ /* Can use a lockless transmit, unless we generate
+ * output sequences
+ */
+ dev->features |= NETIF_F_LLTX;
+ }
+}
+
static int ip6gre_tunnel_init_common(struct net_device *dev)
{
struct ip6_tnl *tunnel;
@@ -1054,6 +1084,8 @@ static int ip6gre_tunnel_init_common(str
if (!(tunnel->parms.flags & IP6_TNL_F_IGN_ENCAP_LIMIT))
dev->mtu -= 8;

+ ip6gre_tnl_init_features(dev);
+
return 0;
}

@@ -1302,11 +1334,6 @@ static const struct net_device_ops ip6gr
.ndo_get_iflink = ip6_tnl_get_iflink,
};

-#define GRE6_FEATURES (NETIF_F_SG | \
- NETIF_F_FRAGLIST | \
- NETIF_F_HIGHDMA | \
- NETIF_F_HW_CSUM)
-
static void ip6gre_tap_setup(struct net_device *dev)
{

@@ -1386,26 +1413,6 @@ static int ip6gre_newlink(struct net *sr
nt->net = dev_net(dev);
ip6gre_tnl_link_config(nt, !tb[IFLA_MTU]);

- dev->features |= GRE6_FEATURES;
- dev->hw_features |= GRE6_FEATURES;
-
- if (!(nt->parms.o_flags & TUNNEL_SEQ)) {
- /* TCP offload with GRE SEQ is not supported, nor
- * can we support 2 levels of outer headers requiring
- * an update.
- */
- if (!(nt->parms.o_flags & TUNNEL_CSUM) ||
- (nt->encap.type == TUNNEL_ENCAP_NONE)) {
- dev->features |= NETIF_F_GSO_SOFTWARE;
- dev->hw_features |= NETIF_F_GSO_SOFTWARE;
- }
-
- /* Can use a lockless transmit, unless we generate
- * output sequences
- */
- dev->features |= NETIF_F_LLTX;
- }
-
err = register_netdevice(dev);
if (err)
goto out;