Subject: Re: [PATCH net V3] bonding: send igmp report for its master

From: Jay Vosburgh <[email-masked]>
Date: Thu, 15 Mar 2012 20:43:19 -0700

Weiping Pan <[email-masked]> wrote:

>Liang Zheng([email-masked]) found that in the following topo,
>bonding does not send igmp report when we trigger a fail-over of bonding.
>
>eth0--
>      |-- bond0 -- br0
>eth1--
>
>modprobe bonding mode=1 miimon=100 resend_igmp=10
>ifconfig bond0 up
>ifenslave bond0 eth0 eth1
>
>brctl addbr br0
>ifconfig br0 192.168.100.2/24 up
>brctl addif br0 bond0
>
>Add 192.168.100.2(br0) into a multicast group, like 224.10.10.10,
>then trigger a fali-over in bonding.
>You can see that parameter "resend_igmp" does not work.
>
>The reason is that when we add br0 into a multicast group,
>it does not propagate multicast knowledge down to its ports.
>
>If we choose to propagate multicast knowledge down to all ports for bridge,
>then we have to track every change that is done to bridge, and keep a backup
>for all ports. It is hard to track, I think.
>
>Instead I choose to modify bonding to send igmp report for its master.
>
>Changelog:
>V2: correct comments
>V3: move this check into bond_resend_igmp_join_requests()
>
>Signed-off-by: Weiping Pan <[email-masked]>
>---
> drivers/net/bonding/bond_main.c |   14 +++++++++++---
> 1 files changed, 11 insertions(+), 3 deletions(-)
>
>diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
>index 435984a..037fdd3 100644
>--- a/drivers/net/bonding/bond_main.c
>+++ b/drivers/net/bonding/bond_main.c
>@@ -766,18 +766,26 @@ static void __bond_resend_igmp_join_requests(struct net_device *dev)
>  */
> static void bond_resend_igmp_join_requests(struct bonding *bond)
> {
>-	struct net_device *vlan_dev;
>+	struct net_device *bond_dev, *vlan_dev, *master_dev;
> 	struct vlan_entry *vlan;
>
> 	read_lock(&bond->lock);
>
>+	bond_dev = bond->dev;
>+
> 	/* rejoin all groups on bond device */
>-	__bond_resend_igmp_join_requests(bond->dev);
>+	__bond_resend_igmp_join_requests(bond_dev);
>+
>+	/* rejoin all groups on its master */
>+	master_dev = bond_dev->master;
>+	if (unlikely(master_dev)) {
>+		__bond_resend_igmp_join_requests(master_dev);
>+	}

	Will this do the right thing if the master is not a bridge?
Granted, right now the only other possible master is a team (since
bonding will not enslave itself), but is this generically safe and
desirable for any possible master_dev?

	-J

> 	/* rejoin all groups on vlan devices */
> 	list_for_each_entry(vlan, &bond->vlan_list, vlan_list) {
> 		rcu_read_lock();
>-		vlan_dev = __vlan_find_dev_deep(bond->dev,
>+		vlan_dev = __vlan_find_dev_deep(bond_dev,
> 						vlan->vlan_id);
> 		rcu_read_unlock();
> 		if (vlan_dev)
>-- 
>1.7.4.4

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