Subject: Re: [PATCH] bonding: allow bond in mode balance-alb to work properly in bridge -try3

From: Jay Vosburgh <[email-masked]>
Date: Wed, 25 Mar 2009 09:31:53 -0700

Jiri Pirko <[email-masked]> wrote:

>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. 

	I think you mean "only balance-alb will simultaneously use
multiple MAC addresses across different slaves."  Yes?

	I ask because the active-backup mode with fail_over_mac=active
will change the bond's MAC to always be the MAC of whatever the
currently active slave is, but I don't think that will trigger the
problem you're talking about (because it'll only use one MAC at a time).

>[...] 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 <[email-masked]>
>
>diff --git a/drivers/net/bonding/bond_alb.c b/drivers/net/bonding/bond_alb.c
>index 27fb7f5..83998f4 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 (!compare_ether_addr_64bits(dest, bond_dev->dev_addr))
>+		return;
>+	read_lock(&bond->lock);
>+	bond_for_each_slave(bond, slave, i) {
>+		if (!compare_ether_addr_64bits(slave->dev->dev_addr, dest)) {
>+			memcpy(dest, bond_dev->dev_addr, ETH_ALEN);
>+			break;
>+		}
>+	}
>+	read_unlock(&bond->lock);
>+}
>+
> void bond_alb_clear_vlan(struct bonding *bond, unsigned short vlan_id)
> {
> 	if (bond->alb_info.current_alb_vlan &&
>diff --git a/drivers/net/bonding/bond_alb.h b/drivers/net/bonding/bond_alb.h
>index 50968f8..77f36fb 100644
>--- a/drivers/net/bonding/bond_alb.h
>+++ b/drivers/net/bonding/bond_alb.h
>@@ -127,6 +127,7 @@ void bond_alb_handle_active_change(struct bonding *bond, struct slave *new_slave
> int bond_alb_xmit(struct sk_buff *skb, struct net_device *bond_dev);
> void bond_alb_monitor(struct work_struct *);
> int bond_alb_set_mac_address(struct net_device *bond_dev, void *addr);
>+void bond_alb_change_dest(struct sk_buff *skb);
> void bond_alb_clear_vlan(struct bonding *bond, unsigned short vlan_id);
> #endif /* __BOND_ALB_H__ */
>
>diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
>index 3d76686..b62fdc4 100644
>--- a/drivers/net/bonding/bond_main.c
>+++ b/drivers/net/bonding/bond_main.c
>@@ -4294,6 +4294,19 @@ unwind:
> 	return res;
> }
>
>+/*
>+ * Called via bond_change_dest_hook.
>+ * note: already called with rcu_read_lock (preempt_disabled)
>+ */
>+void bond_change_dest(struct sk_buff *skb)
>+{
>+	struct net_device *bond_dev = skb->dev;
>+	struct bonding *bond = netdev_priv(bond_dev);
>+
>+	if (bond->params.mode == BOND_MODE_ALB)
>+		bond_alb_change_dest(skb);
>+}
>+
> static int bond_xmit_roundrobin(struct sk_buff *skb, struct net_device *bond_dev)
> {
> 	struct bonding *bond = netdev_priv(bond_dev);
>@@ -5243,6 +5256,8 @@ static int __init bonding_init(void)
> 	register_inetaddr_notifier(&bond_inetaddr_notifier);
> 	bond_register_ipv6_notifier();
>
>+	bond_change_dest_hook = bond_change_dest;
>+
> 	goto out;
> err:
> 	list_for_each_entry(bond, &bond_dev_list, bond_list) {
>@@ -5266,6 +5281,8 @@ static void __exit bonding_exit(void)
> 	unregister_inetaddr_notifier(&bond_inetaddr_notifier);
> 	bond_unregister_ipv6_notifier();
>
>+	bond_change_dest_hook = NULL;
>+
> 	bond_destroy_sysfs();
>
> 	rtnl_lock();
>diff --git a/drivers/net/bonding/bonding.h b/drivers/net/bonding/bonding.h
>index ca849d2..df92b70 100644
>--- a/drivers/net/bonding/bonding.h
>+++ b/drivers/net/bonding/bonding.h
>@@ -375,5 +375,7 @@ static inline void bond_unregister_ipv6_notifier(void)
> }
> #endif
>
>+extern void (*bond_change_dest_hook)(struct sk_buff *skb);
>+
> #endif /* _LINUX_BONDING_H */
>
>diff --git a/net/core/dev.c b/net/core/dev.c
>index e3fe5c7..abe68d9 100644
>--- a/net/core/dev.c
>+++ b/net/core/dev.c
>@@ -2061,6 +2061,13 @@ static inline int deliver_skb(struct sk_buff *skb,
> 	return pt_prev->func(skb, skb->dev, pt_prev, orig_dev);
> }
>
>+#if defined(CONFIG_BONDING) || defined(CONFIG_BONDING_MODULE)
>+void (*bond_change_dest_hook)(struct sk_buff *skb) __read_mostly;
>+EXPORT_SYMBOL(bond_change_dest_hook);
>+#else
>+#define bond_change_dest_hook(skb) do {} while (0)
>+#endif
>+
> #if defined(CONFIG_BRIDGE) || defined (CONFIG_BRIDGE_MODULE)
> /* These hooks defined here for ATM */
> struct net_bridge;
>@@ -2251,10 +2258,12 @@ int netif_receive_skb(struct sk_buff *skb)
> 	null_or_orig = NULL;
> 	orig_dev = skb->dev;
> 	if (orig_dev->master) {
>-		if (skb_bond_should_drop(skb))
>+		if (skb_bond_should_drop(skb)) {
> 			null_or_orig = orig_dev; /* deliver only exact match */
>-		else
>+		} else {
> 			skb->dev = orig_dev->master;
>+			bond_change_dest_hook(skb);

	Since you put the hook outside of the skb_bond_should_drop
function, does the VLAN accelerated receive path do the right thing if,
e.g., there's a VLAN on top of bonding and that VLAN is part of the
bridge?

	-J

---
	-Jay Vosburgh, IBM Linux Technology Center, [email-masked]