bonding: remap muticast addresses without using dev_close() and dev_open()

This patch fixes commit e36b9d16c6a6d0f59803b3ef04ff3c22c3844c10. The approach
there is to call dev_close()/dev_open() whenever the device type is changed in
order to remap the device IP multicast addresses to HW multicast addresses.
This approach suffers from 2 drawbacks:

*. It assumes tha the device is UP when calling dev_close(), or otherwise
   dev_close() has no affect. It is worth to mention that initscripts (Redhat)
   and sysconfig (Suse) doesn't act the same in this matter. 
*. dev_close() has other side affects, like deleting entries from the routing
   table, which might be unnecessary.

The fix here is to directly remap the IP multicast addresses to HW multicast
addresses for a bonding device that changes its type, and nothing else.
   
Reported-by:   Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Signed-off-by: Moni Shoua <monis@voltaire.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 22 insertions, 0 deletions

diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
index 01b4284ed69..d41e5de79a8 100644
--- a/net/ipv4/igmp.c
+++ b/net/ipv4/igmp.c
@@ -1298,6 +1298,28 @@ void ip_mc_dec_group(struct in_device *in_dev, __be32 addr)
 	}
 }
 
+/* Device changing type */
+
+void ip_mc_unmap(struct in_device *in_dev)
+{
+	struct ip_mc_list *i;
+
+	ASSERT_RTNL();
+
+	for (i = in_dev->mc_list; i; i = i->next)
+		igmp_group_dropped(i);
+}
+
+void ip_mc_remap(struct in_device *in_dev)
+{
+	struct ip_mc_list *i;
+
+	ASSERT_RTNL();
+
+	for (i = in_dev->mc_list; i; i = i->next)
+		igmp_group_added(i);
+}
+
 /* Device going down */
 
 void ip_mc_down(struct in_device *in_dev)