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

[PATCH net 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.

Michal Kubecek (2):
  macvlan: introduce IFF_MACVLAN flag and helper functions
  macvlan: disable LRO on lower device instead of macvlan

 drivers/net/macvlan.c      |  2 +-
 include/linux/if_macvlan.h | 26 ++++++++++++++++++++++++++
 include/uapi/linux/if.h    |  1 +
 net/core/dev.c             |  5 +++++
 4 files changed, 33 insertions(+), 1 deletion(-)

-- 
1.8.1.4

[PATCH net 1/2] macvlan: introduce IFF_MACVLAN flag and helper functions

[Michal Kubecek]

Introduce IFF_MACVLAN flag to recognize macvlan devices and two
helper functions, is_macvlan_dev() and macvlan_dev_real_dev().
These work like similar functions for 802.1q VLAN devices.

Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
---
 drivers/net/macvlan.c      |  2 +-
 include/linux/if_macvlan.h | 26 ++++++++++++++++++++++++++
 include/uapi/linux/if.h    |  1 +
 3 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c
index 9bf46bd..3bdac0a 100644
--- a/drivers/net/macvlan.c
+++ b/drivers/net/macvlan.c
@@ -685,7 +685,7 @@ void macvlan_common_setup(struct net_device *dev)
 	ether_setup(dev);
 
 	dev->priv_flags	       &= ~(IFF_XMIT_DST_RELEASE | IFF_TX_SKB_SHARING);
-	dev->priv_flags	       |= IFF_UNICAST_FLT;
+	dev->priv_flags	       |= IFF_UNICAST_FLT | IFF_MACVLAN;
 	dev->netdev_ops		= &macvlan_netdev_ops;
 	dev->destructor		= free_netdev;
 	dev->header_ops		= &macvlan_hard_header_ops;
diff --git a/include/linux/if_macvlan.h b/include/linux/if_macvlan.h
index ddd33fd..8f355f9 100644
--- a/include/linux/if_macvlan.h
+++ b/include/linux/if_macvlan.h
@@ -118,4 +118,30 @@ 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 bool is_macvlan_dev(struct net_device *dev)
+{
+	return dev->priv_flags & IFF_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 bool is_macvlan_dev(struct net_device *dev)
+{
+	return false;
+}
+
+static inline struct net_device *
+macvlan_dev_real_dev(const struct net_device *dev)
+{
+	return NULL;
+}
+#endif
+
 #endif /* _LINUX_IF_MACVLAN_H */
diff --git a/include/uapi/linux/if.h b/include/uapi/linux/if.h
index 1ec407b..d8e48f8 100644
--- a/include/uapi/linux/if.h
+++ b/include/uapi/linux/if.h
@@ -83,6 +83,7 @@
 #define IFF_SUPP_NOFCS	0x80000		/* device supports sending custom FCS */
 #define IFF_LIVE_ADDR_CHANGE 0x100000	/* device supports hardware address
 					 * change when it's running */
+#define IFF_MACVLAN	0x200000	/* macvlan device */
 
 
 #define IF_GET_IFACE	0x0001		/* for querying only */
-- 
1.8.1.4

[PATCH net 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).

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 3430b1e..4af02a9 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"
 
@@ -1425,6 +1426,10 @@ 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 (is_macvlan_dev(dev))
+		dev = macvlan_dev_real_dev(dev);
+
 	dev->wanted_features &= ~NETIF_F_LRO;
 	netdev_update_features(dev);
 
-- 
1.8.1.4

Re: [PATCH net 1/2] macvlan: introduce IFF_MACVLAN flag and helper functions

[John Fastabend]

On 11/8/2013 5:41 AM, Michal Kubecek wrote:
> Introduce IFF_MACVLAN flag to recognize macvlan devices and two
> helper functions, is_macvlan_dev() and macvlan_dev_real_dev().
> These work like similar functions for 802.1q VLAN devices.
>
> Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
> ---
>   drivers/net/macvlan.c      |  2 +-
>   include/linux/if_macvlan.h | 26 ++++++++++++++++++++++++++
>   include/uapi/linux/if.h    |  1 +
>   3 files changed, 28 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c
> index 9bf46bd..3bdac0a 100644
> --- a/drivers/net/macvlan.c
> +++ b/drivers/net/macvlan.c
> @@ -685,7 +685,7 @@ void macvlan_common_setup(struct net_device *dev)
>   	ether_setup(dev);
>
>   	dev->priv_flags	       &= ~(IFF_XMIT_DST_RELEASE | IFF_TX_SKB_SHARING);
> -	dev->priv_flags	       |= IFF_UNICAST_FLT;
> +	dev->priv_flags	       |= IFF_UNICAST_FLT | IFF_MACVLAN;
>   	dev->netdev_ops		= &macvlan_netdev_ops;
>   	dev->destructor		= free_netdev;
>   	dev->header_ops		= &macvlan_hard_header_ops;
> diff --git a/include/linux/if_macvlan.h b/include/linux/if_macvlan.h
> index ddd33fd..8f355f9 100644
> --- a/include/linux/if_macvlan.h
> +++ b/include/linux/if_macvlan.h
> @@ -118,4 +118,30 @@ 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 bool is_macvlan_dev(struct net_device *dev)
> +{
> +	return dev->priv_flags & IFF_MACVLAN;
> +}
> +

I just added this to netdevice.h here,

+static inline bool netif_is_macvlan(struct net_device *dev)
+{
+	return dev->priv_flags & IFF_MACVLAN;
+}
+

although I didn't wrap it in the IS_ENABLED if/else, but a
bitmask in slow path probably doesn't matter. As a precedent
none of the other netif_is_* bitmasks are wrapped like this.

The patch is

commit 2a47fa45d4dfbc54659d28de311a1f764b296a3c
Author: John Fastabend <john.r.fastabend@intel.com>
Date:   Wed Nov 6 09:54:52 2013 -0800

     ixgbe: enable l2 forwarding acceleration for macvlans


I think you need to respin the patch with just the
macvlan_dev_real_dev() part.

Thanks,
John

Re: [PATCH net 1/2] macvlan: introduce IFF_MACVLAN flag and helper functions

[Michal Kubecek]

On Fri, Nov 08, 2013 at 07:06:15AM -0800, John Fastabend wrote:
> 
> I just added this to netdevice.h here,
> 
> +static inline bool netif_is_macvlan(struct net_device *dev)
> +{
> +	return dev->priv_flags & IFF_MACVLAN;
> +}
> +
> 
> although I didn't wrap it in the IS_ENABLED if/else, but a
> bitmask in slow path probably doesn't matter. As a precedent
> none of the other netif_is_* bitmasks are wrapped like this.
> 
> The patch is
> 
> commit 2a47fa45d4dfbc54659d28de311a1f764b296a3c
> Author: John Fastabend <john.r.fastabend@intel.com>
> Date:   Wed Nov 6 09:54:52 2013 -0800
> 
>     ixgbe: enable l2 forwarding acceleration for macvlans
> 
> 
> I think you need to respin the patch with just the
> macvlan_dev_real_dev() part.

My patch also conflicts with

  a6cc0cfa  net: Add layer 2 hardware acceleration operations for macvlan devices

which introduced the IFF_MACVLAN flags (but sets it in
macvlan_common_newlink()). Both of yours are in net-next while mine are
against net (as 2/2 is a bugfix) which is why I didn't notice them.
I'm not sure what to do in such case.

                                                         Michal Kubecek