netdev - Re: [PATCH net-next] ipv4: use next hop exceptions also for input routes

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Message-ID: <alpine.LFD.2.00.1306271146550.2436@ja.ssi.bg>
Date:	Thu, 27 Jun 2013 11:52:14 +0300 (EEST)
From:	Julian Anastasov <ja@....bg>
To:	Timo Teräs <timo.teras@....fi>
cc:	netdev@...r.kernel.org
Subject: Re: [PATCH net-next] ipv4: use next hop exceptions also for input
 routes


	Hello,

On Thu, 27 Jun 2013, Timo Teräs wrote:

> Commit d2d68ba9 (ipv4: Cache input routes in fib_info nexthops)
> assmued that "locally destined, and routed packets, never trigger
> PMTU events or redirects that will be processed by us".
> 
> However, it seems that tunnel devices do trigger PMTU events in certain
> cases. At least ip_gre, ip6_gre, sit, and ipip do use the inner flow's
> skb_dst(skb)->ops->update_pmtu to propage mtu information from the
> outer flows. These can cause the inner flow mtu to be decreased. If
> next hop exceptions are not consulted for pmtu, IP fragmentation will
> not be done properly for these routes.
> 
> It also seems that we really need to have the PMTU information always
> for netfilter TCPMSS clamp-to-pmtu feature to work properly.
> 
> So for the time being, cache separate copies of input routes for
> each next hop exception.
> 
> Signed-off-by: Timo Teräs <timo.teras@....fi>

	Looks good to me

Reviewed-by: Julian Anastasov <ja@....bg>

> ---
> Seems that the previous send was marked as RFC, and got no review
> comments. No alternate patches seem to have been committed either.
> 
> I'm resending now without RFC tag, and rebased against current
> net-next. I've been using this locally for several weeks and have
> not found any problems, and this does fix the two regression bugs
> mentioned above.

Regards

--
Julian Anastasov <ja@....bg>