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From: David Ahern <dsahern@gmail.com>
To: Stefano Brivio <sbrivio@redhat.com>,
	Jan Szewczyk <jan.szewczyk@ericsson.com>
Cc: "davem@davemloft.net" <davem@davemloft.net>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	Wei Wang <weiwan@google.com>, Martin KaFai Lau <kafai@fb.com>,
	Eric Dumazet <edumazet@google.com>
Subject: Re: Question about linux kernel commit: "net/ipv6: move metrics from dst to rt6_info"
Date: Wed, 10 Jul 2019 13:13:03 -0600	[thread overview]
Message-ID: <5981b8d0-cfdf-d230-fa22-cfcfaa5ee4b9@gmail.com> (raw)
In-Reply-To: <20190710210954.530d72a5@elisabeth>

On 7/10/19 1:09 PM, Stefano Brivio wrote:
> Jan,
> 
> On Wed, 10 Jul 2019 12:59:41 +0000
> Jan Szewczyk <jan.szewczyk@ericsson.com> wrote:
> 
>> Hi!
>> I digged up a little further and maybe it's not a problem with MTU
>> itself. I checked every entry I get from RTM_GETROUTE netlink message
>> and after triggering "too big packet" by pinging ipv6address I get
>> exactly the same messages on 4.12 and 4.18, except that the one with
>> that pinged ipv6address is missing on 4.18 at all. What is weird -
>> it's visible when running "ip route get to ipv6address". Do you know
>> why there is a mismatch there?
> 
> If I understand you correctly, an implementation equivalent to 'ip -6
> route list show' (using the NLM_F_DUMP flag) won't show the so-called
> route exception, while 'ip -6 route get' shows it.
> 
> If that's the case: that was broken by commit 2b760fcf5cfb ("ipv6: hook
> up exception table to store dst cache") that landed in 4.15, and fixed
> by net-next commit 1e47b4837f3b ("ipv6: Dump route exceptions if
> requested"). For more details, see the log of this commit itself.
> 

ah, good point. My mind locked on RTM_GETROUTE as a specific route
request not a dump.

  reply	other threads:[~2019-07-10 19:13 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <AM6PR07MB56397A8BC53D9A525BC9C489F2F00@AM6PR07MB5639.eurprd07.prod.outlook.com>
2019-07-10 12:27 ` Question about linux kernel commit: "net/ipv6: move metrics from dst to rt6_info" David Ahern
2019-07-10 12:59   ` Jan Szewczyk
2019-07-10 19:09     ` Stefano Brivio
2019-07-10 19:13       ` David Ahern [this message]
2019-07-11  7:41         ` Jan Szewczyk

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