[PATCH net v3 0/2] macvlan: disable LRO on lowerdev instead of a macvlan

[PATCH net v3 0/2] macvlan: disable LRO on lowerdev instead of a macvlan

[Michal Kubecek]

A customer of ours encountered a problem with LRO on an ixgbe network
card. Analysis showed that it was a known conflict of forwarding and LRO
but the forwarding was enabled in an LXC container where only a macvlan
was, not the ethernet device itself.

I believe the solution is exactly the same as what we do for "normal"
(802.1q) VLAN devices: if dev_disable_lro() is called for such device,
LRO is disabled on the underlying "real" device instead.

v2: adapt to changes merged from net-next

v3: use BUG() in macvlan_dev_real_dev() if compiled without macvlan

Michal Kubecek (2):
  macvlan: introduce macvlan_dev_real_dev() helper function
  macvlan: disable LRO on lower device instead of macvlan

 include/linux/if_macvlan.h | 17 +++++++++++++++++
 net/core/dev.c             |  5 +++++
 2 files changed, 22 insertions(+)

-- 
1.8.1.4

[PATCH net v3 1/2] macvlan: introduce macvlan_dev_real_dev() helper function

[Michal Kubecek]

Introduce helper function macvlan_dev_real_dev which returns the
underlying device of a macvlan device, similar to vlan_dev_real_dev()
for 802.1q VLAN devices.

v2: IFF_MACVLAN flag and equivalent of is_macvlan_dev() were
introduced in the meantime

v3: do BUG() if compiled without macvlan support

Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
---
 include/linux/if_macvlan.h | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/include/linux/if_macvlan.h b/include/linux/if_macvlan.h
index c270285..84ba5ac 100644
--- a/include/linux/if_macvlan.h
+++ b/include/linux/if_macvlan.h
@@ -119,4 +119,21 @@ extern int macvlan_link_register(struct rtnl_link_ops *ops);
 extern netdev_tx_t macvlan_start_xmit(struct sk_buff *skb,
 				      struct net_device *dev);
 
+#if IS_ENABLED(CONFIG_MACVLAN)
+static inline struct net_device *
+macvlan_dev_real_dev(const struct net_device *dev)
+{
+	struct macvlan_dev *macvlan = netdev_priv(dev);
+
+	return macvlan->lowerdev;
+}
+#else
+static inline struct net_device *
+macvlan_dev_real_dev(const struct net_device *dev)
+{
+	BUG();
+	return NULL;
+}
+#endif
+
 #endif /* _LINUX_IF_MACVLAN_H */
-- 
1.8.1.4

[PATCH net v3 2/2] macvlan: disable LRO on lower device instead of macvlan

[Michal Kubecek]

A macvlan device has always LRO disabled so that calling
dev_disable_lro() on it does nothing. If we need to disable LRO
e.g. because

  - the macvlan device is inserted into a bridge
  - IPv6 forwarding is enabled for it
  - it is in a different namespace than lowerdev and IPv4
    forwarding is enabled in it

we need to disable LRO on its underlying device instead (as we
do for 802.1q VLAN devices).

v2: use newly introduced netif_is_macvlan()

Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
---
 net/core/dev.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/net/core/dev.c b/net/core/dev.c
index 974143d..7e00a73 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -131,6 +131,7 @@
 #include <linux/static_key.h>
 #include <linux/hashtable.h>
 #include <linux/vmalloc.h>
+#include <linux/if_macvlan.h>
 
 #include "net-sysfs.h"
 
@@ -1424,6 +1425,10 @@ void dev_disable_lro(struct net_device *dev)
 	if (is_vlan_dev(dev))
 		dev = vlan_dev_real_dev(dev);
 
+	/* the same for macvlan devices */
+	if (netif_is_macvlan(dev))
+		dev = macvlan_dev_real_dev(dev);
+
 	dev->wanted_features &= ~NETIF_F_LRO;
 	netdev_update_features(dev);
 
-- 
1.8.1.4

Re: [PATCH net v3 0/2] macvlan: disable LRO on lowerdev instead of a macvlan

[David Miller]

From: Michal Kubecek <mkubecek@suse.cz>
Date: Fri, 15 Nov 2013 06:18:30 +0100 (CET)

> A customer of ours encountered a problem with LRO on an ixgbe network
> card. Analysis showed that it was a known conflict of forwarding and LRO
> but the forwarding was enabled in an LXC container where only a macvlan
> was, not the ethernet device itself.
> 
> I believe the solution is exactly the same as what we do for "normal"
> (802.1q) VLAN devices: if dev_disable_lro() is called for such device,
> LRO is disabled on the underlying "real" device instead.
> 
> v2: adapt to changes merged from net-next
> 
> v3: use BUG() in macvlan_dev_real_dev() if compiled without macvlan

Series applied, thanks Michal.