On Thu, May 16, 2019 at 01:30:54PM -0700, Wei Wang wrote:
> From: Wei Wang <wei...@google.com>
>
> When inserting route cache into the exception table, the key is
> generated with both src_addr and dest_addr with src addr routing.
> However, current logic always assumes the src_addr used to generate the
> key is a /128 host address. This is not true in the following scenarios:
> 1. When the route is a gateway route or does not have next hop.
> (rt6_is_gw_or_nonexthop() == false)
> 2. When calling ip6_rt_cache_alloc(), saddr is passed in as NULL.
> This means, when looking for a route cache in the exception table, we
> have to do the lookup twice: first time with the passed in /128 host
> address, second time with the src_addr stored in fib6_info.
>
> This solves the pmtu discovery issue reported by Mikael Magnusson where
> a route cache with a lower mtu info is created for a gateway route with
> src addr. However, the lookup code is not able to find this route cache.
>
> Fixes: 2b760fcf5cfb ("ipv6: hook up exception table to store dst cache")
> Reported-by: Mikael Magnusson <mikael.ker...@lists.m7n.se>
> Bisected-by: David Ahern <dsah...@gmail.com>
> Signed-off-by: Wei Wang <wei...@google.com>
> Cc: Martin Lau <ka...@fb.com>
> Cc: Eric Dumazet <eduma...@google.com>
> ---
> Changes from v2:
> - modified the check in rt6_find_cached_rt() to prevent infinite loop
> - add const to src_key to prevent kernel compile warning
>
> Changes from v1:
> - restructure the code to only include the new logic in
> rt6_find_cached_rt()
Acked-by: Martin KaFai Lau <ka...@fb.com>
Thanks for the fix and changes!
