From: David Ahern <dsah...@gmail.com> Date: Wed, May 15, 2019 at 10:33 AM To: Wei Wang Cc: Wei Wang, David Miller, Linux Kernel Network Developers, Martin KaFai Lau, Mikael Magnusson, Eric Dumazet
> On 5/15/19 11:28 AM, Wei Wang wrote: > > From: Wei Wang <wei...@google.com> > > Date: Wed, May 15, 2019 at 10:25 AM > > To: David Ahern > > Cc: Wei Wang, David Miller, Linux Kernel Network Developers, Martin > > KaFai Lau, Mikael Magnusson, Eric Dumazet > > > >>> > >>> What about rt6_remove_exception_rt? > >>> > >>> You can add a 'cache' hook to ip/iproute.c to delete the cached routes > >>> and verify that it works. I seem to have misplaced my patch to do it. > >> I don't think rt6_remove_exception_rt() needs any change. > >> It is because it gets the route cache rt6_info as the input parameter, > >> not specific saddr or daddr from a flow or a packet. > >> It is guaranteed that the hash used in the exception table is > >> generated from rt6_info->rt6i_dst and rt6_info->rt6i_src. > >> > >> For the case where user tries to delete a cache route, ip6_route_del() > >> calls rt6_find_cached_rt() to find the cached route first. And > >> rt6_find_cached_rt() is taken care of to find the cached route > >> according to both passed in src addr and f6i->fib6_src. > >> So I think we are good here. > >> > >> From: David Ahern <dsah...@gmail.com> > >> Date: Wed, May 15, 2019 at 9:38 AM > >> To: Wei Wang, David Miller, <netdev@vger.kernel.org> > >> Cc: Martin KaFai Lau, Wei Wang, Mikael Magnusson, Eric Dumazet > >> > >>> On 5/15/19 9:56 AM, David Ahern wrote: > >>>> You can add a 'cache' hook to ip/iproute.c to delete the cached routes > >>>> and verify that it works. I seem to have misplaced my patch to do it. > >>> > >>> found it. > > > > Thanks. I patched it to iproute2 and tried it. > > The route cache is removed by doing: > > ip netns exec a ./ip -6 route del fd01::c from fd00::a cache > > > > 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? 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
