netdev - Re: [PATCH net] ipv6: fix src addr routing with the exception table

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Date:   Wed, 15 May 2019 11:49:26 -0600
From:   David Ahern <dsahern@...il.com>
To:     Wei Wang <weiwan@...gle.com>
Cc:     Wei Wang <tracywwnj@...il.com>, David Miller <davem@...emloft.net>,
        Linux Kernel Network Developers <netdev@...r.kernel.org>,
        Martin KaFai Lau <kafai@...com>,
        Mikael Magnusson <mikael.kernel@...ts.m7n.se>,
        Eric Dumazet <edumazet@...gle.com>
Subject: Re: [PATCH net] ipv6: fix src addr routing with the exception table

On 5/15/19 11:45 AM, Wei Wang wrote:
>>
>> you have to pass in a device. The first line in ip6_del_cached_rt:
>>
>> if (cfg->fc_ifindex && rt->dst.dev->ifindex != cfg->fc_ifindex)
>>                 goto out;
>>
>> 'ip route get' is one way to check if it has been deleted. We really
>> need to add support for dumping exception routes.
> 
> Without passing in dev, fc_ifindex = 0. So it won't goto out. Isn't it?

ugh, yes, blew right past that.

> The way I checked if the route cache is being removed is by doing:
> ip netns exec a cat /proc/net/rt6_stats
> The 5th counter is the number of cached routes right now in the system.
> 
> The output I get after I run the reproducer:
> # ip netns exec a cat /proc/net/rt6_stats
> 000b 0006 000e 0006 0001 0005 0000
> # ip netns exec a ./ip -6 route del fd01::c from fd00::/64 cache
> # ip netns exec a cat /proc/net/rt6_stats
> 000b 0006 0012 0006 0000 0004 0000
> 
> The same behavior if I pass in dev:
> # ip netns exec a cat /proc/net/rt6_stats
> 000b 0006 000c 0006 0001 0004 0000
> # ip netns exec a ./ip -6 route del fd01::c from fd00::/64 dev vethab cache
> # ip netns exec a cat /proc/net/rt6_stats
> 000b 0006 0013 0006 0000 0003 0000
> 

ok.

Reviewed-by: David Ahern <dsahern@...il.com>