From: Ido Schimmel <ido...@mellanox.com> Date: Sun, 11 Mar 2018 09:44:39 +0200
> Petr says: > > mlxsw_spectrum supports offloading of a tc action mirred egress mirror > to a gretap or ip6gretap netdevice, which necessitates calls to > functions defined in ip_gre, ip6_gre and ip6_tunnel modules. Previously > this was enabled by introducing a hard dependency of MLXSW_SPECTRUM on > NET_IPGRE and IPV6_GRE. However the rest of mlxsw is careful about > picking which modules are absolutely required, and therefore the better > approach is to make mlxsw_spectrum tolerant of absence of one or both of > the GRE flavors. > > One way this might be resolved is by keeping the code in mlxsw_spectrum > intact, and defining defaults for functions that mlxsw_spectrum depends > on. The downsides are that other modules end up littered with these > do-nothing defaults; that the driver ends up carrying quite a bit of > dead code; and that the driver ends up having to explicitly depend on > IPV6_TUNNEL to prevent configurations where mlxsw_spectrum is compiled > in and and ip6_tunnel is a module, something that it currently can treat > as an implementation detail of the IPV6_GRE dependency. > > Alternatively, the driver should just bite the bullet and ifdef-out the > code that handles configurations that are not supported. Since that's > what we are doing for IPv6 dependency, let's do the same for the GRE > flavors. > > Patch #1 introduces a wrapper function for determining the value of > ipv6.sysctl.multipath_hash_policy, which defaults to 0 on non-IPv6 > builds. That function is then used from spectrum_router.c, instead of > the direct variable reference that was introduced there during the short > window when the Spectrum driver had a hard dependency on IPv6. > > Patch #2 moves one function to keep together in one block all the > callbacks for handling (IPv4) gretap mirroring. > > Patch #3 then introduces the ifdefs to hide the irrelevant code. Series applied.
