On Tue, 3 Nov 2020 11:41:33 +0100 Oliver Herms wrote:
> Due to the legacy usage of hard_header_len for SIT tunnels while
> already using infrastructure from net/ipv4/ip_tunnel.c the
> calculation of the path MTU in tnl_update_pmtu is incorrect.
> This leads to unnecessary creation of MTU exceptions for any
> flow going over a SIT tunnel.
>
> As SIT tunnels do not have a header themsevles other than their
> transport (L3, L2) headers we're leaving hard_header_len set to zero
> as tnl_update_pmtu is already taking care of the transport headers
> sizes.
>
> This will also help avoiding unnecessary IPv6 GC runs and spinlock
> contention seen when using SIT tunnels and for more than
> net.ipv6.route.gc_thresh flows.
>
> Fixes: c54419321455 ("GRE: Refactor GRE tunneling code.")
> Signed-off-by: Oliver Herms <oliver.peter.he...@gmail.com>
Applied, thanks! Let's carry on the discussion about ipv6 tunnels,
though, it does look questionable.
