datapath: genetlink: optionally validate strictly/dumps

datapath: genetlink: optionally validate strictly/dumps

This patch backports the following upstream commit within the
openvswitch kernel module with some checks so that it also works
in the older kernel.

Upstream commit:
commit ef6243acb4782df587a4d7d6c310fa5b5d82684b
Author: Johannes Berg <johannes.berg@intel.com>
Date:   Fri Apr 26 14:07:31 2019 +0200

    genetlink: optionally validate strictly/dumps

    Add options to strictly validate messages and dump messages,
    sometimes perhaps validating dump messages non-strictly may
    be required, so add an option for that as well.

    Since none of this can really be applied to existing commands,
    set the options everwhere using the following spatch:

        @@
        identifier ops;
        expression X;
        @@
        struct genl_ops ops[] = {
        ...,
         {
                .cmd = X,
        +       .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
                ...
         },
        ...
        };

    For new commands one should just not copy the .validate 'opt-out'
    flags and thus get strict validation.

    Signed-off-by: Johannes Berg <johannes.berg@intel.com>
    Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Yi-Hung Wei <yihung.wei@gmail.com>
Reviewed-by: Yifeng Sun <pkusunyifeng@gmail.com>
Signed-off-by: Ben Pfaff <blp@ovn.org>