Subject: Re: [PATCH net-next] bonding: allow bond in mode balance-alb to work properly in bridge -try4.1

From: Eric Dumazet <[email-masked]>
Date: Tue, 26 May 2009 18:59:53 +0200

Jiri Pirko a écrit :
> [PATCH net-next] bonding: allow bond in mode balance-alb to work properly in bridge -try4.1
> 
> Hi all.
> 
> The problem is described in following bugzilla:
> https://bugzilla.redhat.com/show_bug.cgi?id=487763
> 
> Basically here's what's going on. In every mode, bonding interface uses the same
> mac address for all enslaved devices (except fail_over_mac). Only balance-alb
> will simultaneously use multiple MAC addresses across different slaves. When you
> put this kind of bond device into a bridge it will only add one of mac adresses
> into a hash list of mac addresses, say X. This mac address is marked as local.
> But this bonding interface also has mac address Y. Now then packet arrives with
> destination address Y, this address is not marked as local and the packed looks
> like it needs to be forwarded. This packet is then lost which is wrong.
> 
> Notice that interfaces can be added and removed from bond while it is in bridge.
> 
> ***
> When the multiple addresses for bridge port approach failed to solve this issue
> due to STP I started to think other way to solve this. I returned to previous
> solution but tweaked one.
> 
> This patch solves the situation in the bonding without touching bridge code.
> For every incoming frame to bonding the destination address is compared to
> current address of the slave device from which tha packet came. If these two
> match destination address is replaced by mac address of the master. This address
> is known by bridge so it is delivered properly.
> 
> I experimentally tried that this works as good as searching through the slave
> list (v4 of this patch).
> 
> I was forced to create a new header because I need to use
> compare_ether_addr_64bits() (defined in linux/etherdevice.h) in
> linux/netdevice.h. I've hit some cross include issues. I think that it's good
> to have skb_bond_should_drop() in a separate file anyway.
> 
> Jirka
> 
> 
> Signed-off-by: Jiri Pirko <[email-masked]>
> 
> diff --git a/include/linux/bonding.h b/include/linux/bonding.h
> new file mode 100644
> index 0000000..3081ddb
> --- /dev/null
> +++ b/include/linux/bonding.h
> @@ -0,0 +1,78 @@
> +/*
> + * include/linux/bonding.h
> + *
> + * Copyright (C) 2009 Jiri Pirko <[email-masked]>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2
> + * as published by the Free Software Foundation.
> + *
> + * Bonding device helpers.
> + */
> +
> +#ifndef _LINUX_BONDING_H
> +#define _LINUX_BONDING_H
> +
> +#ifdef __KERNEL__
> +
> +#include <linux/skbuff.h>
> +#include <linux/netdevice.h>
> +#include <linux/if.h>
> +#include <linux/etherdevice.h>
> +#include <linux/if_ether.h>
> +
> +static inline void skb_bond_set_mac_by_master(struct sk_buff *skb,
> +					      struct net_device *dev,
> +					      struct net_device *master)
> +{
> +	unsigned char *dest = eth_hdr(skb)->h_dest;
> +
> +	if (compare_ether_addr_64bits(dest, master->dev_addr) &&
> +	    !compare_ether_addr_64bits(dest, dev->dev_addr))
> +		memcpy(dest, master->dev_addr, ETH_ALEN);

But couldnt we test skb->pkt_type == PACKET_HOST instead,
Or eth_type_trans() not yet called at this point ?

I would suggest :

if (skb->pkt_type == PACKET_HOST)
	memcpy(dest, master->dev_addr, ETH_ALEN);

> +}
> +
> +/* On bonding slaves other than the currently active slave, suppress
> + * duplicates except for 802.3ad ETH_P_SLOW, alb non-mcast/bcast, and
> + * ARP on active-backup slaves with arp_validate enabled.
> + */
> +static inline int skb_bond_should_drop(struct sk_buff *skb)
> +{
> +	struct net_device *dev = skb->dev;
> +	struct net_device *master = dev->master;
> +
> +	if (master) {
> +		if (master->priv_flags & IFF_MASTER_ARPMON)
> +			dev->last_rx = jiffies;
> +
> +		if ((master->priv_flags & IFF_MASTER_ALB) && master->br_port) {
> +			/* Do address unmangle. The local destination address
> +			 * will be always the one master has. Provides the right
> +			 * functionality in a bridge.
> +			 */
> +			skb_bond_set_mac_by_master(skb, dev, master);
> +		}
> +
> +		if (dev->priv_flags & IFF_SLAVE_INACTIVE) {
> +			if ((dev->priv_flags & IFF_SLAVE_NEEDARP) &&
> +			    skb->protocol == __cpu_to_be16(ETH_P_ARP))
> +				return 0;
> +
> +			if (master->priv_flags & IFF_MASTER_ALB) {
> +				if (skb->pkt_type != PACKET_BROADCAST &&
> +				    skb->pkt_type != PACKET_MULTICAST)
> +					return 0;
> +			}
> +			if (master->priv_flags & IFF_MASTER_8023AD &&
> +			    skb->protocol == __cpu_to_be16(ETH_P_SLOW))
> +				return 0;
> +
> +			return 1;
> +		}
> +	}
> +	return 0;
> +}
> +
> +#endif /* __KERNEL__ */
> +
> +#endif	/* _LINUX_BONDING_H */
> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
> index ae3c209..06e24ae 100644
> --- a/include/linux/netdevice.h
> +++ b/include/linux/netdevice.h
> @@ -1897,39 +1897,6 @@ static inline void netif_set_gso_max_size(struct net_device *dev,
>  	dev->gso_max_size = size;
>  }
>  
> -/* On bonding slaves other than the currently active slave, suppress
> - * duplicates except for 802.3ad ETH_P_SLOW, alb non-mcast/bcast, and
> - * ARP on active-backup slaves with arp_validate enabled.
> - */
> -static inline int skb_bond_should_drop(struct sk_buff *skb)
> -{
> -	struct net_device *dev = skb->dev;
> -	struct net_device *master = dev->master;
> -
> -	if (master) {
> -		if (master->priv_flags & IFF_MASTER_ARPMON)
> -			dev->last_rx = jiffies;
> -
> -		if (dev->priv_flags & IFF_SLAVE_INACTIVE) {
> -			if ((dev->priv_flags & IFF_SLAVE_NEEDARP) &&
> -			    skb->protocol == __cpu_to_be16(ETH_P_ARP))
> -				return 0;
> -
> -			if (master->priv_flags & IFF_MASTER_ALB) {
> -				if (skb->pkt_type != PACKET_BROADCAST &&
> -				    skb->pkt_type != PACKET_MULTICAST)
> -					return 0;
> -			}
> -			if (master->priv_flags & IFF_MASTER_8023AD &&
> -			    skb->protocol == __cpu_to_be16(ETH_P_SLOW))
> -				return 0;
> -
> -			return 1;
> -		}
> -	}
> -	return 0;
> -}
> -
>  extern struct pernet_operations __net_initdata loopback_net_ops;
>  
>  static inline int dev_ethtool_get_settings(struct net_device *dev,
> diff --git a/net/8021q/vlan_core.c b/net/8021q/vlan_core.c
> index 7f7de1a..c6eae40 100644
> --- a/net/8021q/vlan_core.c
> +++ b/net/8021q/vlan_core.c
> @@ -2,6 +2,7 @@
>  #include <linux/netdevice.h>
>  #include <linux/if_vlan.h>
>  #include <linux/netpoll.h>
> +#include <linux/bonding.h>
>  #include "vlan.h"
>  
>  /* VLAN rx hw acceleration helper.  This acts like netif_{rx,receive_skb}(). */
> diff --git a/net/core/dev.c b/net/core/dev.c
> index 241613f..221b43f 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -127,6 +127,7 @@
>  #include <linux/jhash.h>
>  #include <linux/random.h>
>  #include <trace/napi.h>
> +#include <linux/bonding.h>
>  
>  #include "net-sysfs.h"
>  
> --
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