| Message ID | 1345691986.5904.40.camel@edumazet-glaptop |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
于 2012年08月23日 11:19, Eric Dumazet 写道: > From: Eric Dumazet <edumazet@google.com> > > I noticed extra one second delay in device dismantle, tracked down to > a call to dst_dev_event() while some call_rcu() are still in RCU queues. > > These call_rcu() were posted by rt_free(struct rtable *rt) calls. > > We then wait a little (but one second) in netdev_wait_allrefs() before > kicking again NETDEV_UNREGISTER. > > As the call_rcu() are now completed, dst_dev_event() can do the needed > device swap on busy dst. > > To solve this problem, add a new NETDEV_UNREGISTER_FINAL, called > after a rcu_barrier(), but outside of RTNL lock. > > Use NETDEV_UNREGISTER_FINAL with care ! > > Change dst_dev_event() handler to react to NETDEV_UNREGISTER_FINAL > > Also remove NETDEV_UNREGISTER_BATCH, as its not used anymore after > IP cache removal. > > With help from Gao feng > > Signed-off-by: Eric Dumazet <edumazet@google.com> > Cc: Tom Herbert <therbert@google.com> > Cc: Mahesh Bandewar <maheshb@google.com> > Cc: "Eric W. Biederman" <ebiederm@xmission.com> > Cc: Gao feng <gaofeng@cn.fujitsu.com> looks good to me, the lockdep warning message disappeared. -- 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
From: Gao feng <gaofeng@cn.fujitsu.com> Date: Thu, 23 Aug 2012 12:33:03 +0800 > 于 2012年08月23日 11:19, Eric Dumazet 写道: >> From: Eric Dumazet <edumazet@google.com> >> >> I noticed extra one second delay in device dismantle, tracked down to >> a call to dst_dev_event() while some call_rcu() are still in RCU queues. >> >> These call_rcu() were posted by rt_free(struct rtable *rt) calls. >> >> We then wait a little (but one second) in netdev_wait_allrefs() before >> kicking again NETDEV_UNREGISTER. >> >> As the call_rcu() are now completed, dst_dev_event() can do the needed >> device swap on busy dst. >> >> To solve this problem, add a new NETDEV_UNREGISTER_FINAL, called >> after a rcu_barrier(), but outside of RTNL lock. >> >> Use NETDEV_UNREGISTER_FINAL with care ! >> >> Change dst_dev_event() handler to react to NETDEV_UNREGISTER_FINAL >> >> Also remove NETDEV_UNREGISTER_BATCH, as its not used anymore after >> IP cache removal. >> >> With help from Gao feng >> >> Signed-off-by: Eric Dumazet <edumazet@google.com> >> Cc: Tom Herbert <therbert@google.com> >> Cc: Mahesh Bandewar <maheshb@google.com> >> Cc: "Eric W. Biederman" <ebiederm@xmission.com> >> Cc: Gao feng <gaofeng@cn.fujitsu.com> > > looks good to me, the lockdep warning message disappeared. Applied, thanks everyone. -- 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
Eric Dumazet <eric.dumazet@gmail.com> writes: > From: Eric Dumazet <edumazet@google.com> > > I noticed extra one second delay in device dismantle, tracked down to > a call to dst_dev_event() while some call_rcu() are still in RCU queues. > > These call_rcu() were posted by rt_free(struct rtable *rt) calls. > > We then wait a little (but one second) in netdev_wait_allrefs() before > kicking again NETDEV_UNREGISTER. > > As the call_rcu() are now completed, dst_dev_event() can do the needed > device swap on busy dst. > > To solve this problem, add a new NETDEV_UNREGISTER_FINAL, called > after a rcu_barrier(), but outside of RTNL lock. > > Use NETDEV_UNREGISTER_FINAL with care ! > > Change dst_dev_event() handler to react to NETDEV_UNREGISTER_FINAL > > Also remove NETDEV_UNREGISTER_BATCH, as its not used anymore after > IP cache removal. > > With help from Gao feng > > Signed-off-by: Eric Dumazet <edumazet@google.com> > Cc: Tom Herbert <therbert@google.com> > Cc: Mahesh Bandewar <maheshb@google.com> > Cc: "Eric W. Biederman" <ebiederm@xmission.com> > Cc: Gao feng <gaofeng@cn.fujitsu.com> > --- > v3: Gao Feng reported a lockdep issue. > I had to change some notifiers to check NETDEV_UNREGISTER_FINAL > > v2: NETDEV_UNREGISTER_FINAL called outside of rtnl lock > as its more risky, base this patch on net-next > > include/linux/netdevice.h | 2 +- > net/core/dev.c | 22 ++++++++-------------- > net/core/dst.c | 2 +- > net/core/fib_rules.c | 3 ++- > net/core/rtnetlink.c | 2 +- > net/ipv4/devinet.c | 6 +++++- > net/ipv4/fib_frontend.c | 8 ++++---- > net/ipv6/addrconf.c | 6 +++++- > 8 files changed, 27 insertions(+), 24 deletions(-) > > diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h > index 4936f09..9ad7fa8 100644 > --- a/include/linux/netdevice.h > +++ b/include/linux/netdevice.h > @@ -1553,7 +1553,7 @@ struct packet_type { > #define NETDEV_PRE_TYPE_CHANGE 0x000E > #define NETDEV_POST_TYPE_CHANGE 0x000F > #define NETDEV_POST_INIT 0x0010 > -#define NETDEV_UNREGISTER_BATCH 0x0011 > +#define NETDEV_UNREGISTER_FINAL 0x0011 > #define NETDEV_RELEASE 0x0012 > #define NETDEV_NOTIFY_PEERS 0x0013 > #define NETDEV_JOIN 0x0014 > diff --git a/net/core/dev.c b/net/core/dev.c > index 088923f..0640d2a 100644 > --- a/net/core/dev.c > +++ b/net/core/dev.c > @@ -1406,7 +1406,6 @@ rollback: > nb->notifier_call(nb, NETDEV_DOWN, dev); > } > nb->notifier_call(nb, NETDEV_UNREGISTER, dev); > - nb->notifier_call(nb, NETDEV_UNREGISTER_BATCH, dev); > } > } > > @@ -1448,7 +1447,6 @@ int unregister_netdevice_notifier(struct notifier_block *nb) > nb->notifier_call(nb, NETDEV_DOWN, dev); > } > nb->notifier_call(nb, NETDEV_UNREGISTER, dev); > - nb->notifier_call(nb, NETDEV_UNREGISTER_BATCH, dev); > } > } > unlock: > @@ -1468,7 +1466,8 @@ EXPORT_SYMBOL(unregister_netdevice_notifier); > > int call_netdevice_notifiers(unsigned long val, struct net_device *dev) > { > - ASSERT_RTNL(); > + if (val != NETDEV_UNREGISTER_FINAL) > + ASSERT_RTNL(); raw_notifier_call_chain isn't safe without holding some sort of lock. So removing the ASSERT_RTNL assert here is papering over a bug elsewhere in this patch. Without holding a lock for traversing the notifier chain there will be races with network module load and unload that could corrupt this list while we are traversing it. load/unlod. You already have one of your NETDEV_UNREGISTER_FINAL calls under the rtnl_lock so it doesn't look like a burden to put the other call under the rtnl_lock as well. > return raw_notifier_call_chain(&netdev_chain, val, dev); > } > EXPORT_SYMBOL(call_netdevice_notifiers); > @@ -5331,10 +5330,6 @@ static void rollback_registered_many(struct list_head *head) > netdev_unregister_kobject(dev); > } > > - /* Process any work delayed until the end of the batch */ > - dev = list_first_entry(head, struct net_device, unreg_list); > - call_netdevice_notifiers(NETDEV_UNREGISTER_BATCH, dev); > - > synchronize_net(); > > list_for_each_entry(dev, head, unreg_list) > @@ -5787,9 +5782,8 @@ static void netdev_wait_allrefs(struct net_device *dev) > > /* Rebroadcast unregister notification */ > call_netdevice_notifiers(NETDEV_UNREGISTER, dev); > - /* don't resend NETDEV_UNREGISTER_BATCH, _BATCH users > - * should have already handle it the first time */ > - > + rcu_barrier(); You have just added an rcu_barrier() under the rtnl_lock. Can you make this. __rtnl_unlock(); rcu_barrier(); rtnl_lock(); Which will be much better for rtnl_lock hold times. > + call_netdevice_notifiers(NETDEV_UNREGISTER_FINAL, dev); > if (test_bit(__LINK_STATE_LINKWATCH_PENDING, > &dev->state)) { > /* We must not have linkwatch events > @@ -5851,9 +5845,8 @@ void netdev_run_todo(void) > > __rtnl_unlock(); > > - /* Wait for rcu callbacks to finish before attempting to drain > - * the device list. This usually avoids a 250ms wait. > - */ > + > + /* Wait for rcu callbacks to finish before next phase */ > if (!list_empty(&list)) > rcu_barrier(); > > @@ -5862,6 +5855,8 @@ void netdev_run_todo(void) > = list_first_entry(&list, struct net_device, todo_list); > list_del(&dev->todo_list); > + call_netdevice_notifiers(NETDEV_UNREGISTER_FINAL, dev); > + Why are you skipping grapping the rtl_lock here? rtnl_lock(); __rtnl_unlock() doesn't look scary. > if (unlikely(dev->reg_state != NETREG_UNREGISTERING)) { > pr_err("network todo '%s' but state %d\n", > dev->name, dev->reg_state); > @@ -6256,7 +6251,6 @@ int dev_change_net_namespace(struct net_device *dev, struct net *net, const char > the device is just moving and can keep their slaves up. > */ > call_netdevice_notifiers(NETDEV_UNREGISTER, dev); > - call_netdevice_notifiers(NETDEV_UNREGISTER_BATCH, dev); > rtmsg_ifinfo(RTM_DELLINK, dev, ~0U); > > /* > diff --git a/net/core/dst.c b/net/core/dst.c > index 56d6361..f6593d2 100644 > --- a/net/core/dst.c > +++ b/net/core/dst.c > @@ -374,7 +374,7 @@ static int dst_dev_event(struct notifier_block *this, unsigned long event, > struct dst_entry *dst, *last = NULL; > > switch (event) { > - case NETDEV_UNREGISTER: > + case NETDEV_UNREGISTER_FINAL: > case NETDEV_DOWN: > mutex_lock(&dst_gc_mutex); > for (dst = dst_busy_list; dst; dst = dst->next) { > diff --git a/net/core/fib_rules.c b/net/core/fib_rules.c > index ab7db83..5850937 100644 > --- a/net/core/fib_rules.c > +++ b/net/core/fib_rules.c > @@ -711,15 +711,16 @@ static int fib_rules_event(struct notifier_block *this, unsigned long event, > struct net *net = dev_net(dev); > struct fib_rules_ops *ops; > > - ASSERT_RTNL(); > > switch (event) { > case NETDEV_REGISTER: > + ASSERT_RTNL(); > list_for_each_entry(ops, &net->rules_ops, list) > attach_rules(&ops->rules_list, dev); > break; > > case NETDEV_UNREGISTER: > + ASSERT_RTNL(); > list_for_each_entry(ops, &net->rules_ops, list) > detach_rules(&ops->rules_list, dev); > break; > diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c > index 34d975b..c64efcf 100644 > --- a/net/core/rtnetlink.c > +++ b/net/core/rtnetlink.c > @@ -2358,7 +2358,7 @@ static int rtnetlink_event(struct notifier_block *this, unsigned long event, voi > case NETDEV_PRE_TYPE_CHANGE: > case NETDEV_GOING_DOWN: > case NETDEV_UNREGISTER: > - case NETDEV_UNREGISTER_BATCH: > + case NETDEV_UNREGISTER_FINAL: > case NETDEV_RELEASE: > case NETDEV_JOIN: > break; > diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c > index adf273f..6a5e6e4 100644 > --- a/net/ipv4/devinet.c > +++ b/net/ipv4/devinet.c > @@ -1147,8 +1147,12 @@ static int inetdev_event(struct notifier_block *this, unsigned long event, > void *ptr) > { > struct net_device *dev = ptr; > - struct in_device *in_dev = __in_dev_get_rtnl(dev); > + struct in_device *in_dev; > > + if (event == NETDEV_UNREGISTER_FINAL) > + goto out; > + > + in_dev = __in_dev_get_rtnl(dev); > ASSERT_RTNL(); > > if (!in_dev) { > diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c > index 7f073a3..fd7d9ae 100644 > --- a/net/ipv4/fib_frontend.c > +++ b/net/ipv4/fib_frontend.c > @@ -1041,7 +1041,7 @@ static int fib_inetaddr_event(struct notifier_block *this, unsigned long event, > static int fib_netdev_event(struct notifier_block *this, unsigned long event, void *ptr) > { > struct net_device *dev = ptr; > - struct in_device *in_dev = __in_dev_get_rtnl(dev); > + struct in_device *in_dev; > struct net *net = dev_net(dev); > > if (event == NETDEV_UNREGISTER) { > @@ -1050,9 +1050,11 @@ static int fib_netdev_event(struct notifier_block *this, unsigned long event, vo > return NOTIFY_DONE; > } > > - if (!in_dev) > + if (event == NETDEV_UNREGISTER_FINAL) > return NOTIFY_DONE; > > + in_dev = __in_dev_get_rtnl(dev); > + > switch (event) { > case NETDEV_UP: > for_ifa(in_dev) { > @@ -1071,8 +1073,6 @@ static int fib_netdev_event(struct notifier_block *this, unsigned long event, vo > case NETDEV_CHANGE: > rt_cache_flush(dev_net(dev), 0); > break; > - case NETDEV_UNREGISTER_BATCH: > - break; > } > return NOTIFY_DONE; > } > diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c > index 6bc85f7..e581009 100644 > --- a/net/ipv6/addrconf.c > +++ b/net/ipv6/addrconf.c > @@ -2566,10 +2566,14 @@ static int addrconf_notify(struct notifier_block *this, unsigned long event, > void *data) > { > struct net_device *dev = (struct net_device *) data; > - struct inet6_dev *idev = __in6_dev_get(dev); > + struct inet6_dev *idev; > int run_pending = 0; > int err; > > + if (event == NETDEV_UNREGISTER_FINAL) > + return NOTIFY_DONE; > + > + idev = __in6_dev_get(dev); > switch (event) { > case NETDEV_REGISTER: > if (!idev && dev->mtu >= IPV6_MIN_MTU) { -- 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
On Wed, 2012-08-22 at 23:34 -0700, Eric W. Biederman wrote: > raw_notifier_call_chain isn't safe without holding some sort of lock. > So removing the ASSERT_RTNL assert here is papering over a bug elsewhere > in this patch. > > Without holding a lock for traversing the notifier chain there will > be races with network module load and unload that could corrupt > this list while we are traversing it. > load/unlod. > > You already have one of your NETDEV_UNREGISTER_FINAL calls under the > rtnl_lock so it doesn't look like a burden to put the other call under > the rtnl_lock as well. Hmm right, I have been fooled by the rcu_dereference_raw() calls in notifier_call_chain() I'll send an update, thanks ! -- 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
On Thu, 2012-08-23 at 05:19 +0200, Eric Dumazet wrote: > From: Eric Dumazet <edumazet@google.com> > > I noticed extra one second delay in device dismantle, tracked down to > a call to dst_dev_event() while some call_rcu() are still in RCU queues. > > These call_rcu() were posted by rt_free(struct rtable *rt) calls. > > We then wait a little (but one second) in netdev_wait_allrefs() before > kicking again NETDEV_UNREGISTER. > > As the call_rcu() are now completed, dst_dev_event() can do the needed > device swap on busy dst. > > To solve this problem, add a new NETDEV_UNREGISTER_FINAL, called > after a rcu_barrier(), but outside of RTNL lock. [...] So what happens when this races with register_netdevice_notifier()? Ben.
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 4936f09..9ad7fa8 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -1553,7 +1553,7 @@ struct packet_type { #define NETDEV_PRE_TYPE_CHANGE 0x000E #define NETDEV_POST_TYPE_CHANGE 0x000F #define NETDEV_POST_INIT 0x0010 -#define NETDEV_UNREGISTER_BATCH 0x0011 +#define NETDEV_UNREGISTER_FINAL 0x0011 #define NETDEV_RELEASE 0x0012 #define NETDEV_NOTIFY_PEERS 0x0013 #define NETDEV_JOIN 0x0014 diff --git a/net/core/dev.c b/net/core/dev.c index 088923f..0640d2a 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -1406,7 +1406,6 @@ rollback: nb->notifier_call(nb, NETDEV_DOWN, dev); } nb->notifier_call(nb, NETDEV_UNREGISTER, dev); - nb->notifier_call(nb, NETDEV_UNREGISTER_BATCH, dev); } } @@ -1448,7 +1447,6 @@ int unregister_netdevice_notifier(struct notifier_block *nb) nb->notifier_call(nb, NETDEV_DOWN, dev); } nb->notifier_call(nb, NETDEV_UNREGISTER, dev); - nb->notifier_call(nb, NETDEV_UNREGISTER_BATCH, dev); } } unlock: @@ -1468,7 +1466,8 @@ EXPORT_SYMBOL(unregister_netdevice_notifier); int call_netdevice_notifiers(unsigned long val, struct net_device *dev) { - ASSERT_RTNL(); + if (val != NETDEV_UNREGISTER_FINAL) + ASSERT_RTNL(); return raw_notifier_call_chain(&netdev_chain, val, dev); } EXPORT_SYMBOL(call_netdevice_notifiers); @@ -5331,10 +5330,6 @@ static void rollback_registered_many(struct list_head *head) netdev_unregister_kobject(dev); } - /* Process any work delayed until the end of the batch */ - dev = list_first_entry(head, struct net_device, unreg_list); - call_netdevice_notifiers(NETDEV_UNREGISTER_BATCH, dev); - synchronize_net(); list_for_each_entry(dev, head, unreg_list) @@ -5787,9 +5782,8 @@ static void netdev_wait_allrefs(struct net_device *dev) /* Rebroadcast unregister notification */ call_netdevice_notifiers(NETDEV_UNREGISTER, dev); - /* don't resend NETDEV_UNREGISTER_BATCH, _BATCH users - * should have already handle it the first time */ - + rcu_barrier(); + call_netdevice_notifiers(NETDEV_UNREGISTER_FINAL, dev); if (test_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state)) { /* We must not have linkwatch events @@ -5851,9 +5845,8 @@ void netdev_run_todo(void) __rtnl_unlock(); - /* Wait for rcu callbacks to finish before attempting to drain - * the device list. This usually avoids a 250ms wait. - */ + + /* Wait for rcu callbacks to finish before next phase */ if (!list_empty(&list)) rcu_barrier(); @@ -5862,6 +5855,8 @@ void netdev_run_todo(void) = list_first_entry(&list, struct net_device, todo_list); list_del(&dev->todo_list); + call_netdevice_notifiers(NETDEV_UNREGISTER_FINAL, dev); + if (unlikely(dev->reg_state != NETREG_UNREGISTERING)) { pr_err("network todo '%s' but state %d\n", dev->name, dev->reg_state); @@ -6256,7 +6251,6 @@ int dev_change_net_namespace(struct net_device *dev, struct net *net, const char the device is just moving and can keep their slaves up. */ call_netdevice_notifiers(NETDEV_UNREGISTER, dev); - call_netdevice_notifiers(NETDEV_UNREGISTER_BATCH, dev); rtmsg_ifinfo(RTM_DELLINK, dev, ~0U); /* diff --git a/net/core/dst.c b/net/core/dst.c index 56d6361..f6593d2 100644 --- a/net/core/dst.c +++ b/net/core/dst.c @@ -374,7 +374,7 @@ static int dst_dev_event(struct notifier_block *this, unsigned long event, struct dst_entry *dst, *last = NULL; switch (event) { - case NETDEV_UNREGISTER: + case NETDEV_UNREGISTER_FINAL: case NETDEV_DOWN: mutex_lock(&dst_gc_mutex); for (dst = dst_busy_list; dst; dst = dst->next) { diff --git a/net/core/fib_rules.c b/net/core/fib_rules.c index ab7db83..5850937 100644 --- a/net/core/fib_rules.c +++ b/net/core/fib_rules.c @@ -711,15 +711,16 @@ static int fib_rules_event(struct notifier_block *this, unsigned long event, struct net *net = dev_net(dev); struct fib_rules_ops *ops; - ASSERT_RTNL(); switch (event) { case NETDEV_REGISTER: + ASSERT_RTNL(); list_for_each_entry(ops, &net->rules_ops, list) attach_rules(&ops->rules_list, dev); break; case NETDEV_UNREGISTER: + ASSERT_RTNL(); list_for_each_entry(ops, &net->rules_ops, list) detach_rules(&ops->rules_list, dev); break; diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c index 34d975b..c64efcf 100644 --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -2358,7 +2358,7 @@ static int rtnetlink_event(struct notifier_block *this, unsigned long event, voi case NETDEV_PRE_TYPE_CHANGE: case NETDEV_GOING_DOWN: case NETDEV_UNREGISTER: - case NETDEV_UNREGISTER_BATCH: + case NETDEV_UNREGISTER_FINAL: case NETDEV_RELEASE: case NETDEV_JOIN: break; diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c index adf273f..6a5e6e4 100644 --- a/net/ipv4/devinet.c +++ b/net/ipv4/devinet.c @@ -1147,8 +1147,12 @@ static int inetdev_event(struct notifier_block *this, unsigned long event, void *ptr) { struct net_device *dev = ptr; - struct in_device *in_dev = __in_dev_get_rtnl(dev); + struct in_device *in_dev; + if (event == NETDEV_UNREGISTER_FINAL) + goto out; + + in_dev = __in_dev_get_rtnl(dev); ASSERT_RTNL(); if (!in_dev) { diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c index 7f073a3..fd7d9ae 100644 --- a/net/ipv4/fib_frontend.c +++ b/net/ipv4/fib_frontend.c @@ -1041,7 +1041,7 @@ static int fib_inetaddr_event(struct notifier_block *this, unsigned long event, static int fib_netdev_event(struct notifier_block *this, unsigned long event, void *ptr) { struct net_device *dev = ptr; - struct in_device *in_dev = __in_dev_get_rtnl(dev); + struct in_device *in_dev; struct net *net = dev_net(dev); if (event == NETDEV_UNREGISTER) { @@ -1050,9 +1050,11 @@ static int fib_netdev_event(struct notifier_block *this, unsigned long event, vo return NOTIFY_DONE; } - if (!in_dev) + if (event == NETDEV_UNREGISTER_FINAL) return NOTIFY_DONE; + in_dev = __in_dev_get_rtnl(dev); + switch (event) { case NETDEV_UP: for_ifa(in_dev) { @@ -1071,8 +1073,6 @@ static int fib_netdev_event(struct notifier_block *this, unsigned long event, vo case NETDEV_CHANGE: rt_cache_flush(dev_net(dev), 0); break; - case NETDEV_UNREGISTER_BATCH: - break; } return NOTIFY_DONE; } diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c index 6bc85f7..e581009 100644 --- a/net/ipv6/addrconf.c +++ b/net/ipv6/addrconf.c @@ -2566,10 +2566,14 @@ static int addrconf_notify(struct notifier_block *this, unsigned long event, void *data) { struct net_device *dev = (struct net_device *) data; - struct inet6_dev *idev = __in6_dev_get(dev); + struct inet6_dev *idev; int run_pending = 0; int err; + if (event == NETDEV_UNREGISTER_FINAL) + return NOTIFY_DONE; + + idev = __in6_dev_get(dev); switch (event) { case NETDEV_REGISTER: if (!idev && dev->mtu >= IPV6_MIN_MTU) {