[PATCH] net: Resend IGMP memberships upon peer notification.

When we notify peers of potential changes,  it's also good to update
IGMP memberships.  For example, during VM migration, updating IGMP
memberships will redirect existing multicast streams to the VM at the
new location.

Signed-off-by: Vladislav Yasevich <redacted>
---
 net/core/dev.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/core/dev.c b/net/core/dev.c
index a229bf0..1ed927d 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c

@@ -1272,6 +1272,7 @@ void netdev_notify_peers(struct net_device *dev)
 {
 	rtnl_lock();
 	call_netdevice_notifiers(NETDEV_NOTIFY_PEERS, dev);
+	call_netdevice_notifiers(NETDEV_RESEND_IGMP, dev);
 	rtnl_unlock();
 }
 EXPORT_SYMBOL(netdev_notify_peers);

-- 
2.7.4

On Tue, Mar 14, 2017 at 08:58:08AM -0400, Vladislav Yasevich wrote:

When we notify peers of potential changes,  it's also good to update
IGMP memberships.  For example, during VM migration, updating IGMP
memberships will redirect existing multicast streams to the VM at the
new location.

Signed-off-by: Vladislav Yasevich <redacted>

what will happen on the source? will the snooping bridge remove
membership on port removal as appropriate?

On Tue, Mar 14, 2017 at 08:58:08AM -0400, Vladislav Yasevich wrote:

When we notify peers of potential changes,  it's also good to update
IGMP memberships.  For example, during VM migration, updating IGMP
memberships will redirect existing multicast streams to the VM at the
new location.

Signed-off-by: Vladislav Yasevich <redacted>

Seems to make sense

Acked-by: Michael S. Tsirkin <mst@redhat.com>

but I also think there's another problem: source does not
leave the groups on migration. So I think we should add code on the
host - it's snooping IGMPs so it should be able to leave groups on the
source when VM is disconnected.

From: Vladislav Yasevich <redacted>
Date: Tue, 14 Mar 2017 08:58:08 -0400

When we notify peers of potential changes,  it's also good to update
IGMP memberships.  For example, during VM migration, updating IGMP
memberships will redirect existing multicast streams to the VM at the
new location.

Signed-off-by: Vladislav Yasevich <redacted>

Applied, thanks Vlad.