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Date: Fri, 10 Sep 2010 16:58:31 -0400
From: Brian Haley <brian.haley@...com>
To: David Miller <davem@...emloft.net>,
YOSHIFUJI Hideaki <yoshfuji@...ux-ipv6.org>
CC: "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: [PATCH] IPv6: Change addrconf code to deal with link changes better
I recently started noticing that sometimes I wasn't seeing all the "normal"
IPv6 packets (DAD, MLD, Router Solicit) when I was bringing-up interfaces.
I found that sometimes the link on some NICs was going up-down-up like
this:
ADDRCONF(NETDEV_UP): eth3: link is not ready
e1000e: eth3 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: None
ADDRCONF(NETDEV_CHANGE): eth3: link becomes ready
(DAD queued here)
e1000e: eth3 NIC Link is Down
e1000e: eth3 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: None
This is all tcpdump showed on a remote system:
IP6 fe80::21f:29ff:fe59:fac9 > ff02::2: ICMP6, router solicitation, length 16
IP6 fe80::21f:29ff:fe59:fac9 > ff02::2: ICMP6, router solicitation, length 16
The addrconf code isn't written to handle this case, and won't restart DAD.
With the patch below I get this (DAD_KICK was for debugging):
ADDRCONF(NETDEV_UP): eth6: link is not ready
e1000e: eth6 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: None
ADDRCONF(NETDEV_CHANGE): eth6: link becomes ready
DAD_KICK(fe80::21f:29ff:fe59:faca): eth6
e1000e: eth6 NIC Link is Down
ADDRCONF(NETDEV_CHANGE): eth6: link is not ready
e1000e: eth6 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: None
ADDRCONF(NETDEV_CHANGE): eth6: link becomes ready
DAD_KICK(fe80::21f:29ff:fe59:faca): eth6
And corresponding tcpdump:
IP6 :: > ff02::1:ff59:faca: ICMP6, neighbor solicitation, who has fe80::21f:29ff:fe59:faca, length 24
IP6 :: > ff02::16: HBH ICMP6, multicast listener report v2, 1 group record(s), length 28
IP6 fe80::21f:29ff:fe59:faca > ff02::2: ICMP6, router solicitation, length 16
I also noticed that sometimes during these blips that addrconf_dad_kick()
could be called twice, transmitting two DAD packets and resetting the
timer another second into the future, so I introduced a "Need DAD" state
to signify that DAD has not been started yet. With both of these applied
the behavior is much better.
--
Change the IPv6 addrconf code to handle the case where the NIC link
state goes UP-DOWN-UP by removing all the autoconfigured addresses
when it goes down, so that when it comes back up they will get added
again and DAD will be triggered. Also added a "Need DAD" state so that
we don't accidentally start it twice for the same address, sending a
duplicate packet and delaying when the address is available for use.
Signed-off-by: Brian Haley <brian.haley@...com>
diff --git a/include/net/if_inet6.h b/include/net/if_inet6.h
index f95ff8d..57432f1 100644
--- a/include/net/if_inet6.h
+++ b/include/net/if_inet6.h
@@ -33,6 +33,7 @@
#ifdef __KERNEL__
enum {
+ INET6_IFADDR_STATE_NEEDDAD,
INET6_IFADDR_STATE_DAD,
INET6_IFADDR_STATE_POSTDAD,
INET6_IFADDR_STATE_UP,
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 5bc893e..fabafc7 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -2517,13 +2517,27 @@ static int addrconf_notify(struct notifier_block *this, unsigned long event,
if (!idev && dev->mtu >= IPV6_MIN_MTU)
idev = ipv6_add_dev(dev);
- if (idev) {
- idev->if_flags |= IF_READY;
+ /*
+ * Only start DAD if the device is ready, IF_READY
+ * will have been set by ipv6_add_dev() if so.
+ */
+ if (idev && idev->if_flags & IF_READY)
run_pending = 1;
- }
} else {
if (!addrconf_qdisc_ok(dev)) {
- /* device is still not ready. */
+ /*
+ * Device is still not ready. If we've already
+ * configured addresses, remove them now as
+ * we'll need to start DAD all over again.
+ */
+ printk(KERN_INFO
+ "ADDRCONF(NETDEV_CHANGE): %s: "
+ "link is not ready\n",
+ dev->name);
+
+ if (idev && idev->if_flags & IF_READY)
+ addrconf_ifdown(dev, 0);
+
break;
}
@@ -2736,7 +2750,7 @@ static int addrconf_ifdown(struct net_device *dev, int how)
/* Flag it for later restoration when link comes up */
ifa->flags |= IFA_F_TENTATIVE;
- ifa->state = INET6_IFADDR_STATE_DAD;
+ ifa->state = INET6_IFADDR_STATE_NEEDDAD;
write_unlock_bh(&idev->lock);
@@ -2847,6 +2861,7 @@ static void addrconf_dad_kick(struct inet6_ifaddr *ifp)
rand_num = net_random() % (idev->cnf.rtr_solicit_delay ? : 1);
ifp->probes = idev->cnf.dad_transmits;
+ ifp->state = INET6_IFADDR_STATE_DAD;
addrconf_mod_timer(ifp, AC_DAD, rand_num);
}
@@ -2992,7 +3007,7 @@ static void addrconf_dad_run(struct inet6_dev *idev)
list_for_each_entry(ifp, &idev->addr_list, if_list) {
spin_lock(&ifp->lock);
if (ifp->flags & IFA_F_TENTATIVE &&
- ifp->state == INET6_IFADDR_STATE_DAD)
+ ifp->state == INET6_IFADDR_STATE_NEEDDAD)
addrconf_dad_kick(ifp);
spin_unlock(&ifp->lock);
}
--
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