netdev - Re: [PATCH] ipv6: addrconf: don't remove address state on ifdown if the address is being kept

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Date:	Wed, 27 Oct 2010 23:45:17 -0700
From:	Lorenzo Colitti <lorenzo@...gle.com>
To:	netdev@...r.kernel.org
Cc:	Maciej Żenczykowski <maze@...gle.com>,
	David Miller <davem@...emloft.net>,
	Brian Haley <brian.haley@...com>
Subject: Re: [PATCH] ipv6: addrconf: don't remove address state on ifdown if
 the address is being kept

On Wed, Oct 27, 2010 at 9:16 PM, Lorenzo Colitti <lorenzo@...gle.com> wrote:
> Fix it so that none of this state is updated if the address is being kept on the interface.

Or, since the logic of the patched code is a little hard to follow,
here's an alternative patch against 2.6.36. I think it does exactly
the same as the previous patch, but it moves things around to make the
result more readable.

Tested: Added a statically configured IPv6 address to an interface,
started ping, brought link down, brought link up again. When link came
up ping kept on going and "ip -6 maddr" showed that the host was still
subscribed to there

Signed-off-by: Lorenzo Colitti <lorenzo@...gle.com>

--- 2.6.36-orig/net/ipv6/addrconf.c	2010-10-20 13:30:22.000000000 -0700
+++ linux-2.6.36/net/ipv6/addrconf.c	2010-10-27 23:26:57.000000000 -0700
@@ -2737,10 +2737,6 @@ static int addrconf_ifdown(struct net_de
 			/* Flag it for later restoration when link comes up */
 			ifa->flags |= IFA_F_TENTATIVE;
 			ifa->state = INET6_IFADDR_STATE_DAD;
-
-			write_unlock_bh(&idev->lock);
-
-			in6_ifa_hold(ifa);
 		} else {
 			list_del(&ifa->if_list);

@@ -2755,19 +2751,15 @@ static int addrconf_ifdown(struct net_de
 			ifa->state = INET6_IFADDR_STATE_DEAD;
 			spin_unlock_bh(&ifa->state_lock);

-			if (state == INET6_IFADDR_STATE_DEAD)
-				goto put_ifa;
+			if (state == INET6_IFADDR_STATE_DEAD) {
+				in6_ifa_put(ifa);
+			} else {
+				__ipv6_ifa_notify(RTM_DELADDR, ifa);
+				atomic_notifier_call_chain(&inet6addr_chain,
+							   NETDEV_DOWN, ifa);
+			}
+			write_lock_bh(&idev->lock);
 		}
-
-		__ipv6_ifa_notify(RTM_DELADDR, ifa);
-		if (ifa->state == INET6_IFADDR_STATE_DEAD)
-			atomic_notifier_call_chain(&inet6addr_chain,
-						   NETDEV_DOWN, ifa);
-
-put_ifa:
-		in6_ifa_put(ifa);
-
-		write_lock_bh(&idev->lock);
 	}

 	list_splice(&keep_list, &idev->addr_list);
--
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