genetlink: mark families as __ro_after_init

Now genl_register_family() is the only thing (other than the
users themselves, perhaps, but I didn't find any doing that)
writing to the family struct.

In all families that I found, genl_register_family() is only
called from __init functions (some indirectly, in which case
I've add __init annotations to clarifly things), so all can
actually be marked __ro_after_init.

This protects the data structure from accidental corruption.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c
index ad6a111a..fa87601 100644
--- a/net/openvswitch/datapath.c
+++ b/net/openvswitch/datapath.c
@@ -670,7 +670,7 @@ static const struct genl_ops dp_packet_genl_ops[] = {
 	}
 };
 
-static struct genl_family dp_packet_genl_family = {
+static struct genl_family dp_packet_genl_family __ro_after_init = {
 	.hdrsize = sizeof(struct ovs_header),
 	.name = OVS_PACKET_FAMILY,
 	.version = OVS_PACKET_VERSION,
@@ -1435,7 +1435,7 @@ static const struct genl_ops dp_flow_genl_ops[] = {
 	},
 };
 
-static struct genl_family dp_flow_genl_family = {
+static struct genl_family dp_flow_genl_family __ro_after_init = {
 	.hdrsize = sizeof(struct ovs_header),
 	.name = OVS_FLOW_FAMILY,
 	.version = OVS_FLOW_VERSION,
@@ -1821,7 +1821,7 @@ static const struct genl_ops dp_datapath_genl_ops[] = {
 	},
 };
 
-static struct genl_family dp_datapath_genl_family = {
+static struct genl_family dp_datapath_genl_family __ro_after_init = {
 	.hdrsize = sizeof(struct ovs_header),
 	.name = OVS_DATAPATH_FAMILY,
 	.version = OVS_DATAPATH_VERSION,
@@ -2243,7 +2243,7 @@ static const struct genl_ops dp_vport_genl_ops[] = {
 	},
 };
 
-struct genl_family dp_vport_genl_family = {
+struct genl_family dp_vport_genl_family __ro_after_init = {
 	.hdrsize = sizeof(struct ovs_header),
 	.name = OVS_VPORT_FAMILY,
 	.version = OVS_VPORT_VERSION,
@@ -2272,7 +2272,7 @@ static void dp_unregister_genl(int n_families)
 		genl_unregister_family(dp_genl_families[i]);
 }
 
-static int dp_register_genl(void)
+static int __init dp_register_genl(void)
 {
 	int err;
 	int i;