compat: Move genl_ops policy to genl_family

Upstream commit:
    commit 3b0f31f2b8c9fb348e4530b88f6b64f9621f83d6
    Author: Johannes Berg <johannes.berg@intel.com>
    Date:   Thu Mar 21 22:51:02 2019 +0100

    genetlink: make policy common to family

    Since maxattr is common, the policy can't really differ sanely,
    so make it common as well.

    The only user that did in fact manage to make a non-common policy
    is taskstats, which has to be really careful about it (since it's
    still using a common maxattr!). This is no longer supported, but
    we can fake it using pre_doit.

    This reduces the size of e.g. nl80211.o (which has lots of commands):

       text	   data	    bss	    dec	    hex	filename
     398745	  14323	   2240	 415308	  6564c	net/wireless/nl80211.o (before)
     397913	  14331	   2240	 414484	  65314	net/wireless/nl80211.o (after)
    --------------------------------
       -832      +8       0    -824

    Which is obviously just 8 bytes for each command, and an added 8
    bytes for the new policy pointer. I'm not sure why the ops list is
    counted as .text though.

    Most of the code transformations were done using the following spatch:
        @ops@
        identifier OPS;
        expression POLICY;
        @@
        struct genl_ops OPS[] = {
        ...,
         {
        -	.policy = POLICY,
         },
        ...
        };

        @@
        identifier ops.OPS;
        expression ops.POLICY;
        identifier fam;
        expression M;
        @@
        struct genl_family fam = {
                .ops = OPS,
                .maxattr = M,
        +       .policy = POLICY,
                ...
        };

    This also gets rid of devlink_nl_cmd_region_read_dumpit() accessing
    the cb->data as ops, which we want to change in a later genl patch.

    Signed-off-by: Johannes Berg <johannes.berg@intel.com>
    Signed-off-by: David S. Miller <davem@davemloft.net>

Since commit 3b0f31f2b8c9f ("genetlink: make policy common to family")
the policy field of the genl_ops structure has been moved into the
genl_family structure.  Add necessary compat layer infrastructure
to still support older kernels.

Acked-by: Yi-Hung Wei <yihung.wei@gmail.com>
Signed-off-by: Greg Rose <gvrose8192@gmail.com>
Signed-off-by: Ben Pfaff <blp@ovn.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/acinclude.m4 b/acinclude.m4
index 3a555ad93..729d2c65d 100644
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -1050,6 +1050,9 @@ AC_DEFUN([OVS_CHECK_LINUX_COMPAT], [
                   [OVS_DEFINE([HAVE_DST_OPS_CONFIRM_NEIGH])])
   OVS_GREP_IFELSE([$KSRC/include/net/inet_frag.h], [fqdir],
                   [OVS_DEFINE([HAVE_INET_FRAG_FQDIR])])
+  OVS_FIND_FIELD_IFELSE([$KSRC/include/net/genetlink.h], [genl_ops],
+                        [policy],
+                        [OVS_DEFINE([HAVE_GENL_OPS_POLICY])])
 
   if cmp -s datapath/linux/kcompat.h.new \
             datapath/linux/kcompat.h >/dev/null 2>&1; then