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>

2 files changed, 4 insertions, 4 deletions

diff --git a/include/linux/genl_magic_func.h b/include/linux/genl_magic_func.h
index 83f81ac53282..6cb82301d8e9 100644
--- a/include/linux/genl_magic_func.h
+++ b/include/linux/genl_magic_func.h
@@ -233,7 +233,6 @@ const char *CONCAT_(GENL_MAGIC_FAMILY, _genl_cmd_to_str)(__u8 cmd)
 {								\
 	handler							\
 	.cmd = op_name,						\
-	.policy	= CONCAT_(GENL_MAGIC_FAMILY, _tla_nl_policy),	\
 },
 
 #define ZZZ_genl_ops		CONCAT_(GENL_MAGIC_FAMILY, _genl_ops)
@@ -290,7 +289,8 @@ static struct genl_family ZZZ_genl_family __ro_after_init = {
 #ifdef GENL_MAGIC_FAMILY_HDRSZ
 	.hdrsize = NLA_ALIGN(GENL_MAGIC_FAMILY_HDRSZ),
 #endif
-	.maxattr = ARRAY_SIZE(drbd_tla_nl_policy)-1,
+	.maxattr = ARRAY_SIZE(CONCAT_(GENL_MAGIC_FAMILY, _tla_nl_policy))-1,
+	.policy	= CONCAT_(GENL_MAGIC_FAMILY, _tla_nl_policy),
 	.ops = ZZZ_genl_ops,
 	.n_ops = ARRAY_SIZE(ZZZ_genl_ops),
 	.mcgrps = ZZZ_genl_mcgrps,
diff --git a/include/net/genetlink.h b/include/net/genetlink.h
index aa2e5888f18d..6850c7b1a3a6 100644
--- a/include/net/genetlink.h
+++ b/include/net/genetlink.h
@@ -26,6 +26,7 @@ struct genl_info;
  * @name: name of family
  * @version: protocol version
  * @maxattr: maximum number of attributes supported
+ * @policy: netlink policy
  * @netnsok: set to true if the family can handle network
  *	namespaces and should be presented in all of them
  * @parallel_ops: operations can be called in parallel and aren't
@@ -56,6 +57,7 @@ struct genl_family {
 	unsigned int		maxattr;
 	bool			netnsok;
 	bool			parallel_ops;
+	const struct nla_policy *policy;
 	int			(*pre_doit)(const struct genl_ops *ops,
 					    struct sk_buff *skb,
 					    struct genl_info *info);
@@ -124,14 +126,12 @@ static inline int genl_err_attr(struct genl_info *info, int err,
  * @cmd: command identifier
  * @internal_flags: flags used by the family
  * @flags: flags
- * @policy: attribute validation policy
  * @doit: standard command callback
  * @start: start callback for dumps
  * @dumpit: callback for dumpers
  * @done: completion callback for dumps
  */
 struct genl_ops {
-	const struct nla_policy	*policy;
 	int		       (*doit)(struct sk_buff *skb,
 				       struct genl_info *info);
 	int		       (*start)(struct netlink_callback *cb);