netdev - Re: [PATCH] bonding: allow bond in mode balance-alb to work properly in bridge -try2

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Date:	Wed, 25 Mar 2009 15:39:24 +0100
From:	Jiri Pirko <jpirko@...hat.com>
To:	Eric Dumazet <dada1@...mosbay.com>
Cc:	linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
	jgarzik@...ox.com, davem@...emloft.net,
	shemminger@...ux-foundation.org, bridge@...ts.linux-foundation.org,
	fubar@...ibm.com, bonding-devel@...ts.sourceforge.net,
	kaber@...sh.net, mschmidt@...hat.com
Subject: Re: [PATCH] bonding: allow bond in mode balance-alb to work
	properly in bridge -try2

Wed, Mar 25, 2009 at 02:40:43PM CET, dada1@...mosbay.com wrote:
>Jiri Pirko a écrit :
>> (resend)
>> 
>> 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 for mode balance-alb. 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.
>> 
>> This patch solves the situation in the bonding without touching bridge code,
>> as Patrick suggested. For every incoming frame to bonding it searches the
>> destination address in slaves list and if any of slave addresses matches, it
>> rewrites the address in frame by the adress of bonding master. This ensures that
>> all frames comming thru the bonding in alb mode have the same address.
>> 
>> Jirka
>> 
>> 
>> Signed-off-by: Jiri Pirko <jpirko@...hat.com>
>> 
>> diff --git a/drivers/net/bonding/bond_alb.c b/drivers/net/bonding/bond_alb.c
>> index 27fb7f5..2838be0 100644
>> --- a/drivers/net/bonding/bond_alb.c
>> +++ b/drivers/net/bonding/bond_alb.c
>> @@ -1762,6 +1762,26 @@ int bond_alb_set_mac_address(struct net_device *bond_dev, void *addr)
>>  	return 0;
>>  }
>>  
>> +void bond_alb_change_dest(struct sk_buff *skb)
>> +{
>> +	struct net_device *bond_dev = skb->dev;
>> +	struct bonding *bond = netdev_priv(bond_dev);
>> +	unsigned char *dest = eth_hdr(skb)->h_dest;
>> +	struct slave *slave;
>> +	int i;
>> +
>> +	if (!memcmp(dest, bond_dev->dev_addr, ETH_ALEN))
>> +		return;
>> +	read_lock(&bond->lock);
>
>
>Its a pity bonding doesnt use RCU and needs this read_lock(&bond->lock)

Sure it is...
>
>
>> +	bond_for_each_slave(bond, slave, i) {
>> +		if (!memcmp(slave->dev->dev_addr, dest, ETH_ALEN)) {
>
>compare_ether_addr() (or even better compare_ether_addr_64bits()) instead of memcmp() ?

Okay, I'll use compare_ether_addr_64bits and do the repost later on...
>
>> +			memcpy(dest, bond_dev->dev_addr, ETH_ALEN);
>> +			break;
>> +		}
>> +	}
>> +	read_unlock(&bond->lock);
>> +}
>> +
>
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