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 14:40:43 +0100
From:	Eric Dumazet <dada1@...mosbay.com>
To:	Jiri Pirko <jpirko@...hat.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

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)


> +	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() ?

> +			memcpy(dest, bond_dev->dev_addr, ETH_ALEN);
> +			break;
> +		}
> +	}
> +	read_unlock(&bond->lock);
> +}
> +

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