| Message ID | 20090108171415.1d282743@extreme |
|---|---|
| State | RFC, archived |
| Delegated to: | David Miller |
| Headers | show |
On Friday 09 January 2009 03:14:15 ext Stephen Hemminger, you wrote: > When an interface goes down, IPV6 deletes all addresses unlike IPV4. This > is a problem since it can break routing protocols and other applications. > It looks like this was done to handle DAD, but is a big stick solution when > other code is possible. > > The following patch changes the behaviour to delete link local addresses > but keep all configured addresses and restart DAD when interface comes back > up. Let alone the backward compatibility problem for a minute. I have two _other_ problems with this: 1/ If DAD should fail when the interface is brought back up, wouldn't all the EAU-64 autoconfigured address become invalid, rather than just the link-local one? 2/ In some case the link-local address is assigned by userland, no different from the other ones. At least miredo is behaving this way.
--- a/net/ipv6/addrconf.c 2009-01-08 16:43:04.921305933 -0800 +++ b/net/ipv6/addrconf.c 2009-01-08 16:47:04.000301344 -0800 @@ -2678,18 +2678,26 @@ static int addrconf_ifdown(struct net_de write_lock_bh(&idev->lock); } #endif - while ((ifa = idev->addr_list) != NULL) { - idev->addr_list = ifa->if_next; - ifa->if_next = NULL; - ifa->dead = 1; - addrconf_del_timer(ifa); - write_unlock_bh(&idev->lock); - - __ipv6_ifa_notify(RTM_DELADDR, ifa); - atomic_notifier_call_chain(&inet6addr_chain, NETDEV_DOWN, ifa); - in6_ifa_put(ifa); - - write_lock_bh(&idev->lock); + /* clear regular address list on removal */ + bifa = &idev->addr_list; + while ((ifa = *bifa) != NULL) { + if (how || (ipv6_addr_type(&ifa->addr) & IPV6_ADDR_LINKLOCAL)) { + *bifa = ifa->if_next; + ifa->if_next = NULL; + ifa->dead = 1; + addrconf_del_timer(ifa); + write_unlock_bh(&idev->lock); + + __ipv6_ifa_notify(RTM_DELADDR, ifa); + atomic_notifier_call_chain(&inet6addr_chain, NETDEV_DOWN, ifa); + in6_ifa_put(ifa); + + write_lock_bh(&idev->lock); + } else { + /* Force duplicate address detection when link resumes */ + ifa->flags |= IFA_F_TENTATIVE; + bifa = &ifa->if_next; + } } write_unlock_bh(&idev->lock);
When an interface goes down, IPV6 deletes all addresses unlike IPV4. This is a problem since it can break routing protocols and other applications. It looks like this was done to handle DAD, but is a big stick solution when other code is possible. The following patch changes the behaviour to delete link local addresses but keep all configured addresses and restart DAD when interface comes back up. See also: https://kerneltrap.org/mailarchive/linux-netdev/2008/3/25/1252064/thread Signed-off-by: Stephen Hemminger <shemminger@vyatta.com> -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html