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>

fs/dlm/netlink.c

@@ -72,7 +72,7 @@ static struct genl_ops dlm_nl_ops[] = {
 	},
 };
 
-static struct genl_family family = {
+static struct genl_family family __ro_after_init = {
 	.name		= DLM_GENL_NAME,
 	.version	= DLM_GENL_VERSION,
 	.ops		= dlm_nl_ops,

fs/quota/netlink.c

@@ -12,7 +12,7 @@ static const struct genl_multicast_group quota_mcgrps[] = {
 };
 
 /* Netlink family structure for quota */
-static struct genl_family quota_genl_family = {
+static struct genl_family quota_genl_family __ro_after_init = {
 	.module = THIS_MODULE,
 	.hdrsize = 0,
 	.name = "VFS_DQUOT",