* [Patch net] ipv6: only call ip6_route_dev_notify() once for NETDEV_UNREGISTER
@ 2017-06-20 18:42 Cong Wang
2017-06-21 3:01 ` jeffy
` (2 more replies)
0 siblings, 3 replies; 5+ messages in thread
From: Cong Wang @ 2017-06-20 18:42 UTC (permalink / raw)
To: netdev; +Cc: jeffy.chen, Cong Wang, David Ahern
In commit 242d3a49a2a1 ("ipv6: reorder ip6_route_dev_notifier after ipv6_dev_notf")
I assumed NETDEV_REGISTER and NETDEV_UNREGISTER are paired,
unfortunately, as reported by jeffy, netdev_wait_allrefs()
could rebroadcast NETDEV_UNREGISTER event until all refs are
gone.
We have to add an additional check to avoid this corner case.
For netdev_wait_allrefs() dev->reg_state is NETREG_UNREGISTERED,
for dev_change_net_namespace(), dev->reg_state is
NETREG_REGISTERED. So check for dev->reg_state != NETREG_UNREGISTERED.
Fixes: 242d3a49a2a1 ("ipv6: reorder ip6_route_dev_notifier after ipv6_dev_notf")
Reported-by: jeffy <jeffy.chen@rock-chips.com>
Cc: David Ahern <dsahern@gmail.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
---
net/ipv6/route.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 7cebd95..322bd62 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -3722,7 +3722,11 @@ static int ip6_route_dev_notify(struct notifier_block *this,
net->ipv6.ip6_blk_hole_entry->dst.dev = dev;
net->ipv6.ip6_blk_hole_entry->rt6i_idev = in6_dev_get(dev);
#endif
- } else if (event == NETDEV_UNREGISTER) {
+ } else if (event == NETDEV_UNREGISTER &&
+ dev->reg_state != NETREG_UNREGISTERED) {
+ /* NETDEV_UNREGISTER could be fired for multiple times by
+ * netdev_wait_allrefs(). Make sure we only call this once.
+ */
in6_dev_put(net->ipv6.ip6_null_entry->rt6i_idev);
#ifdef CONFIG_IPV6_MULTIPLE_TABLES
in6_dev_put(net->ipv6.ip6_prohibit_entry->rt6i_idev);
--
2.5.5
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [Patch net] ipv6: only call ip6_route_dev_notify() once for NETDEV_UNREGISTER
2017-06-20 18:42 [Patch net] ipv6: only call ip6_route_dev_notify() once for NETDEV_UNREGISTER Cong Wang
@ 2017-06-21 3:01 ` jeffy
2017-06-21 3:08 ` jeffy
2017-06-21 3:16 ` David Ahern
2017-06-22 15:07 ` David Miller
2 siblings, 1 reply; 5+ messages in thread
From: jeffy @ 2017-06-21 3:01 UTC (permalink / raw)
To: Cong Wang, netdev; +Cc: David Ahern
Hi Cong Wang,
i don't know much about net core, maybe i'm misreading the code...but
On 06/21/2017 02:42 AM, Cong Wang wrote:
> In commit 242d3a49a2a1 ("ipv6: reorder ip6_route_dev_notifier after ipv6_dev_notf")
> I assumed NETDEV_REGISTER and NETDEV_UNREGISTER are paired,
> unfortunately, as reported by jeffy, netdev_wait_allrefs()
> could rebroadcast NETDEV_UNREGISTER event until all refs are
> gone.
>
> We have to add an additional check to avoid this corner case.
> For netdev_wait_allrefs() dev->reg_state is NETREG_UNREGISTERED,
> for dev_change_net_namespace(), dev->reg_state is
> NETREG_REGISTERED. So check for dev->reg_state != NETREG_UNREGISTERED.
i saw we are calling NETDEV_REGISTER in these cases:
1/ register_netdevice_notifier:
the paired unregister would be:
a) normal unregister: rollback_registered_many
b) the error path:
register_netdevice_notifier->rollback jump label
2/ register_netdevice:
the paired unregister would both be rollback_registered_many for
normal/error cases
3/ dev_change_net_namespace:
the paired unregister is the one right before the register notify
i think we are handling all register notifies, but only unregister
notify from rollback_registered_many now?
>
> Fixes: 242d3a49a2a1 ("ipv6: reorder ip6_route_dev_notifier after ipv6_dev_notf")
> Reported-by: jeffy <jeffy.chen@rock-chips.com>
> Cc: David Ahern <dsahern@gmail.com>
> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
> ---
> net/ipv6/route.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/net/ipv6/route.c b/net/ipv6/route.c
> index 7cebd95..322bd62 100644
> --- a/net/ipv6/route.c
> +++ b/net/ipv6/route.c
> @@ -3722,7 +3722,11 @@ static int ip6_route_dev_notify(struct notifier_block *this,
> net->ipv6.ip6_blk_hole_entry->dst.dev = dev;
> net->ipv6.ip6_blk_hole_entry->rt6i_idev = in6_dev_get(dev);
> #endif
> - } else if (event == NETDEV_UNREGISTER) {
> + } else if (event == NETDEV_UNREGISTER &&
> + dev->reg_state != NETREG_UNREGISTERED) {
> + /* NETDEV_UNREGISTER could be fired for multiple times by
> + * netdev_wait_allrefs(). Make sure we only call this once.
> + */
> in6_dev_put(net->ipv6.ip6_null_entry->rt6i_idev);
> #ifdef CONFIG_IPV6_MULTIPLE_TABLES
> in6_dev_put(net->ipv6.ip6_prohibit_entry->rt6i_idev);
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [Patch net] ipv6: only call ip6_route_dev_notify() once for NETDEV_UNREGISTER
2017-06-21 3:01 ` jeffy
@ 2017-06-21 3:08 ` jeffy
0 siblings, 0 replies; 5+ messages in thread
From: jeffy @ 2017-06-21 3:08 UTC (permalink / raw)
To: Cong Wang, netdev; +Cc: David Ahern
Hi Cong Wang,
oh, oops, i did misread.
also, Tested-by: Jeffy Chen <jeffy.chen@rock-chips.com>
On 06/21/2017 11:01 AM, jeffy wrote:
> Hi Cong Wang,
>
> i don't know much about net core, maybe i'm misreading the code...but
>
> On 06/21/2017 02:42 AM, Cong Wang wrote:
>> In commit 242d3a49a2a1 ("ipv6: reorder ip6_route_dev_notifier after
>> ipv6_dev_notf")
>> I assumed NETDEV_REGISTER and NETDEV_UNREGISTER are paired,
>> unfortunately, as reported by jeffy, netdev_wait_allrefs()
>> could rebroadcast NETDEV_UNREGISTER event until all refs are
>> gone.
>>
>> We have to add an additional check to avoid this corner case.
>> For netdev_wait_allrefs() dev->reg_state is NETREG_UNREGISTERED,
>> for dev_change_net_namespace(), dev->reg_state is
>> NETREG_REGISTERED. So check for dev->reg_state != NETREG_UNREGISTERED.
>
> i saw we are calling NETDEV_REGISTER in these cases:
> 1/ register_netdevice_notifier:
> the paired unregister would be:
> a) normal unregister: rollback_registered_many
> b) the error path:
> register_netdevice_notifier->rollback jump label
>
> 2/ register_netdevice:
> the paired unregister would both be rollback_registered_many for
> normal/error cases
>
> 3/ dev_change_net_namespace:
> the paired unregister is the one right before the register notify
>
> i think we are handling all register notifies, but only unregister
> notify from rollback_registered_many now?
>
you are checking for NETREG_UNREGISTERED, so only filter out the
unregistered after rollback_registered_many, so that indeed covers all
cases :)
>
>>
>> Fixes: 242d3a49a2a1 ("ipv6: reorder ip6_route_dev_notifier after
>> ipv6_dev_notf")
>> Reported-by: jeffy <jeffy.chen@rock-chips.com>
>> Cc: David Ahern <dsahern@gmail.com>
>> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
>> ---
>> net/ipv6/route.c | 6 +++++-
>> 1 file changed, 5 insertions(+), 1 deletion(-)
>>
>> diff --git a/net/ipv6/route.c b/net/ipv6/route.c
>> index 7cebd95..322bd62 100644
>> --- a/net/ipv6/route.c
>> +++ b/net/ipv6/route.c
>> @@ -3722,7 +3722,11 @@ static int ip6_route_dev_notify(struct
>> notifier_block *this,
>> net->ipv6.ip6_blk_hole_entry->dst.dev = dev;
>> net->ipv6.ip6_blk_hole_entry->rt6i_idev = in6_dev_get(dev);
>> #endif
>> - } else if (event == NETDEV_UNREGISTER) {
>> + } else if (event == NETDEV_UNREGISTER &&
>> + dev->reg_state != NETREG_UNREGISTERED) {
>> + /* NETDEV_UNREGISTER could be fired for multiple times by
>> + * netdev_wait_allrefs(). Make sure we only call this once.
>> + */
>> in6_dev_put(net->ipv6.ip6_null_entry->rt6i_idev);
>> #ifdef CONFIG_IPV6_MULTIPLE_TABLES
>> in6_dev_put(net->ipv6.ip6_prohibit_entry->rt6i_idev);
>>
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [Patch net] ipv6: only call ip6_route_dev_notify() once for NETDEV_UNREGISTER
2017-06-20 18:42 [Patch net] ipv6: only call ip6_route_dev_notify() once for NETDEV_UNREGISTER Cong Wang
2017-06-21 3:01 ` jeffy
@ 2017-06-21 3:16 ` David Ahern
2017-06-22 15:07 ` David Miller
2 siblings, 0 replies; 5+ messages in thread
From: David Ahern @ 2017-06-21 3:16 UTC (permalink / raw)
To: Cong Wang, netdev; +Cc: jeffy.chen
On 6/20/17 2:42 PM, Cong Wang wrote:
> In commit 242d3a49a2a1 ("ipv6: reorder ip6_route_dev_notifier after ipv6_dev_notf")
> I assumed NETDEV_REGISTER and NETDEV_UNREGISTER are paired,
> unfortunately, as reported by jeffy, netdev_wait_allrefs()
> could rebroadcast NETDEV_UNREGISTER event until all refs are
> gone.
>
> We have to add an additional check to avoid this corner case.
> For netdev_wait_allrefs() dev->reg_state is NETREG_UNREGISTERED,
> for dev_change_net_namespace(), dev->reg_state is
> NETREG_REGISTERED. So check for dev->reg_state != NETREG_UNREGISTERED.
>
> Fixes: 242d3a49a2a1 ("ipv6: reorder ip6_route_dev_notifier after ipv6_dev_notf")
> Reported-by: jeffy <jeffy.chen@rock-chips.com>
> Cc: David Ahern <dsahern@gmail.com>
> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
> ---
> net/ipv6/route.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
Acked-by: David Ahern <dsahern@gmail.com>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [Patch net] ipv6: only call ip6_route_dev_notify() once for NETDEV_UNREGISTER
2017-06-20 18:42 [Patch net] ipv6: only call ip6_route_dev_notify() once for NETDEV_UNREGISTER Cong Wang
2017-06-21 3:01 ` jeffy
2017-06-21 3:16 ` David Ahern
@ 2017-06-22 15:07 ` David Miller
2 siblings, 0 replies; 5+ messages in thread
From: David Miller @ 2017-06-22 15:07 UTC (permalink / raw)
Cc: netdev, jeffy.chen, dsahern
From: Cong Wang <xiyou.wangcong@gmail.com>
Date: Tue, 20 Jun 2017 11:42:27 -0700
> In commit 242d3a49a2a1 ("ipv6: reorder ip6_route_dev_notifier after ipv6_dev_notf")
> I assumed NETDEV_REGISTER and NETDEV_UNREGISTER are paired,
> unfortunately, as reported by jeffy, netdev_wait_allrefs()
> could rebroadcast NETDEV_UNREGISTER event until all refs are
> gone.
>
> We have to add an additional check to avoid this corner case.
> For netdev_wait_allrefs() dev->reg_state is NETREG_UNREGISTERED,
> for dev_change_net_namespace(), dev->reg_state is
> NETREG_REGISTERED. So check for dev->reg_state != NETREG_UNREGISTERED.
>
> Fixes: 242d3a49a2a1 ("ipv6: reorder ip6_route_dev_notifier after ipv6_dev_notf")
> Reported-by: jeffy <jeffy.chen@rock-chips.com>
> Cc: David Ahern <dsahern@gmail.com>
> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Applied.
^ permalink raw reply [flat|nested] 5+ messages in thread
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2017-06-20 18:42 [Patch net] ipv6: only call ip6_route_dev_notify() once for NETDEV_UNREGISTER Cong Wang
2017-06-21 3:01 ` jeffy
2017-06-21 3:08 ` jeffy
2017-06-21 3:16 ` David Ahern
2017-06-22 15:07 ` David Miller
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