From: shengyong <shengyong1@huawei•com>
To: Steffen Klassert <steffen.klassert@secunet•com>
Cc: <davem@davemloft•net>, <netdev@vger•kernel.org>,
<yangyingliang@huawei•com>, <hannes@redhat•com>
Subject: Re: Question: should local address be expired when updating PMTU?
Date: Wed, 4 Feb 2015 09:59:54 +0800 [thread overview]
Message-ID: <54D17D1A.3020706@huawei.com> (raw)
In-Reply-To: <20150203120140.GU13046@secunet.com>
在 2015/2/3 20:01, Steffen Klassert 写道:
> On Tue, Feb 03, 2015 at 06:54:19PM +0800, shengyong wrote:
>>
>>
>> 在 2015/2/3 17:28, Steffen Klassert 写道:
>>> On Mon, Feb 02, 2015 at 04:20:24PM +0800, shengyong wrote:
>>>
>>> We first need to find out why you receive this Packet Too Big message,
>> The packet is sent by a commercial-off-the-shelf testcase, and I can reproduce the
>> situation by using scapy and creating a packet as the following:
>>
>> $ cat packet-too-big.py
>> #!/usr/bin/python
>>
>> from scapy.all import *
>>
>> # fe80::800:27ff:fe00:0 is linklocal addr of PC
>> # fe80::a00:27ff:fe1a:e2a0 is linklocal addr of VM
>> base=IPv6(src='fe80::800:27ff:fe00:0',dst='fe80::a00:27ff:fe1a:e2a0')
>> pkt_too_big=ICMPv6PacketTooBig(mtu=1024)
>> ext_base=IPv6(src='fe80::a00:27ff:fe1a:e2a0',dst='fe80::a00:27ff:fe1a:e2a0',plen=24)
>> ext_nd_na=ICMPv6ND_NA()
>>
>> packet=base/pkt_too_big/ext_base/ext_nd_na
>> send(packet)
>
> So it is not a valid pmtu update, this make life easier.
>
> Can you please test the patch below (compile tested only)?
Sorry, the later. I test it on 3.10-stable. It can fix this problem. So maybe this is a bug?
And the 3 approaches (different flags are used: RTF_LOCAL, IFF_LOOPBACK and RTF_CACHE) in
these mails can fix the expire of local address. I'm confused about these flags:
* RTF_LOCAL: the entries of local address, like address binded to the native NIC
* RTF_CACHE: all cached entries
* IFF_LOOPBACK: this is a device-related flag, which has the same meaning as RTF_LOCAL
Am I right? If so, I think RTF_LOCAL is appropriate, because we just want entries of local
addresses to be not expired and we don't care other entries (I think if they get expired,
a neigh discovery could find them back).
thx,
Sheng
>
> This should fix your problem, and in combination with the two patches I sent
> out last week, it should cure the whole 'expiring of uncached routes' problem.
>
> diff --git a/net/ipv6/route.c b/net/ipv6/route.c
> index 49596535..4ccfb9c 100644
> --- a/net/ipv6/route.c
> +++ b/net/ipv6/route.c
> @@ -1156,7 +1156,8 @@ static void ip6_rt_update_pmtu(struct dst_entry *dst, struct sock *sk,
> struct rt6_info *rt6 = (struct rt6_info *)dst;
>
> dst_confirm(dst);
> - if (mtu < dst_mtu(dst) && rt6->rt6i_dst.plen == 128) {
> + if (mtu < dst_mtu(dst) && rt6->rt6i_dst.plen == 128 &&
> + (rt6->rt6i_flags & RTF_CACHE)) {
> struct net *net = dev_net(dst->dev);
>
> rt6->rt6i_flags |= RTF_MODIFIED;
> --
> 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
>
> .
>
next prev parent reply other threads:[~2015-02-04 2:01 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-02 8:20 Question: should local address be expired when updating PMTU? shengyong
2015-02-02 21:31 ` David Miller
2015-02-03 0:52 ` Alex Gartrell
2015-02-03 1:28 ` shengyong
2015-02-03 2:10 ` Calvin Owens
2015-02-03 3:21 ` shengyong
2015-02-03 9:28 ` Steffen Klassert
2015-02-03 10:54 ` shengyong
2015-02-03 12:01 ` Steffen Klassert
2015-02-04 1:59 ` shengyong [this message]
2015-02-05 7:21 ` Steffen Klassert
2015-02-27 2:37 ` shengyong
2015-02-27 10:32 ` Steffen Klassert
2015-03-30 10:32 ` Steffen Klassert
2015-03-30 10:33 ` [PATCH RFC 1/3] ipv6: Fix after pmtu events dissapearing host routes Steffen Klassert
2015-03-30 11:15 ` Sheng Yong
2015-03-30 18:24 ` Martin Lau
2015-04-01 8:09 ` Steffen Klassert
2015-03-30 10:33 ` [PATCH RFC 2/3] ipv6: Extend the route lookups to low priority metrics Steffen Klassert
2015-03-30 10:34 ` [PATCH RFC 3/3] ipv6: Don't update pmtu on uncached routes Steffen Klassert
2015-03-30 11:13 ` Question: should local address be expired when updating PMTU? Sheng Yong
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=54D17D1A.3020706@huawei.com \
--to=shengyong1@huawei$(echo .)com \
--cc=davem@davemloft$(echo .)net \
--cc=hannes@redhat$(echo .)com \
--cc=netdev@vger$(echo .)kernel.org \
--cc=steffen.klassert@secunet$(echo .)com \
--cc=yangyingliang@huawei$(echo .)com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox