From: Alexander Duyck <alexander.duyck@gmail.com>
To: Hannes Frederic Sowa <hannes@stressinduktion.org>,
netdev@vger.kernel.org
Subject: Re: [PATCH net-next] ipv6: recreate ipv6 link-local addresses when increasing MTU over IPV6_MIN_MTU
Date: Mon, 26 Oct 2015 10:07:32 -0700 [thread overview]
Message-ID: <562E5DD4.40908@gmail.com> (raw)
In-Reply-To: <1445875501.168420.420547673.4BB6C209@webmail.messagingengine.com>
On 10/26/2015 09:05 AM, Hannes Frederic Sowa wrote:
> Hi Alex,
>
> On Mon, Oct 26, 2015, at 16:52, Alexander Duyck wrote:
>> On 10/26/2015 07:36 AM, Hannes Frederic Sowa wrote:
>>> Take into consideration that the interface might be disabled for IPv6,
>>> thus switch event type.
>>>
>>> Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
>>> ---
>>> net/ipv6/addrconf.c | 7 +++++--
>>> 1 file changed, 5 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
>>> index d0c685c..c2dcebe 100644
>>> --- a/net/ipv6/addrconf.c
>>> +++ b/net/ipv6/addrconf.c
>>> @@ -3149,6 +3149,7 @@ static int addrconf_notify(struct notifier_block *this, unsigned long event,
>>>
>>> case NETDEV_UP:
>>> case NETDEV_CHANGE:
>>> +netdev_change:
>>> if (dev->flags & IFF_SLAVE)
>>> break;
>>>
>>> @@ -3244,8 +3245,10 @@ static int addrconf_notify(struct notifier_block *this, unsigned long event,
>>>
>>> if (!idev && dev->mtu >= IPV6_MIN_MTU) {
>>> idev = ipv6_add_dev(dev);
>>> - if (!IS_ERR(idev))
>>> - break;
>>> + if (!IS_ERR(idev)) {
>>> + event = NETDEV_UP;
>>> + goto netdev_change;
>>> + }
>>> }
>>>
>>> /*
>> Seems like this code isn't quite correct. You are calling ipv6_add_dev
>> for slave devices, and if I understand things correctly I don't believe
>> that was happening before and may be an unintended side effect.
> Hmm, could you quickly help me where I get into this situation? I made
> sure I enter the NETDEV_UP part before the IFF_SLAVE test and
> disable_ipv6 te
I think I was getting a bit a head of myself. I was looking over the
NETDEV_UP code and thinking that we could just fall into that path since
it is already calling ipv6_add_dev. However now I am wondering if maybe
we need to look at adding an idev allocation somewhere before the
disable_ipv6 check. I assume that is why you were allocating the idev
before you were getting into NETDEV_UP?
>> You might want to instead just make it so that you only do the jump, and
>> perhaps change the code in the NETDEV_UP/NETDEV_CHANGE section so that
>> you test for NETDEV_CHANGE instead of NETDEV_UP. That should be enough
>> to get the effect you are looking for and I believe there would be no
>> change to behaviour other than adding IPv6 link-local addresses when the
>> MTU is increased.
>>
>> Give me a bit and I can submit an alternative that may actually work out
>> a bit better I think.
> If you go the NETDEV_CHANGE route instead of NETDEV_UP, you end up with
> the IF_READY flag already set from ipv6_add_dev and thus won't do any
> initialization of the device.
What I meant was that you don't need to change the event. If you change
the check inside the NETDEV_UP/CHANGE code path so that it tests for
event != NETDEV_CHANGE instead of event == NETDEV_UP you don't need to
change the event type.
> Sure, I wait.
Might be a bit longer. I just realized that I think there is another
bug here where you are going through the NETDEV_UP path even though the
interface isn't up. I'll run through some testing this morning to work
out the kinks.
- Alex
next prev parent reply other threads:[~2015-10-26 17:07 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-26 14:36 [PATCH net-next] ipv6: recreate ipv6 link-local addresses when increasing MTU over IPV6_MIN_MTU Hannes Frederic Sowa
2015-10-26 15:52 ` Alexander Duyck
2015-10-26 16:05 ` Hannes Frederic Sowa
2015-10-26 17:07 ` Alexander Duyck [this message]
2015-10-26 17:21 ` Hannes Frederic Sowa
2015-10-26 19:05 ` Hannes Frederic Sowa
2015-10-26 16:33 ` Hannes Frederic Sowa
2015-10-26 19:16 ` Jay Vosburgh
2015-10-26 20:45 ` Hannes Frederic Sowa
2015-10-26 20:52 ` Alexander Duyck
2015-10-26 18:06 ` [net-next PATCH v2] " Alexander Duyck
2015-10-30 9:11 ` David Miller
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