genetlink: allow making ops const

Allow making the ops array const by not modifying the ops
flags on registration but rather only when ops are sent
out in the family information.

No users are updated yet except for the pre_doit/post_doit
calls in wireless (the only ones that exist now.)

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

1 files changed, 21 insertions, 15 deletions

diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c
index d8273b057763..a7c62d3d05a1 100644
--- a/net/netlink/genetlink.c
+++ b/net/netlink/genetlink.c
@@ -106,7 +106,7 @@ static struct genl_family *genl_family_find_byname(char *name)
         return NULL;
 }
 
-static struct genl_ops *genl_get_cmd(u8 cmd, struct genl_family *family)
+static const struct genl_ops *genl_get_cmd(u8 cmd, struct genl_family *family)
 {
         int i;
 
@@ -283,7 +283,8 @@ static void genl_unregister_mc_groups(struct genl_family *family)
                 __genl_unregister_mc_group(family, grp);
 }
 
-static int genl_validate_add_ops(struct genl_family *family, struct genl_ops *ops,
+static int genl_validate_add_ops(struct genl_family *family,
+                                 const struct genl_ops *ops,
                                  unsigned int n_ops)
 {
         int i, j;
@@ -294,12 +295,6 @@ static int genl_validate_add_ops(struct genl_family *family, struct genl_ops *op
                 for (j = i + 1; j < n_ops; j++)
                         if (ops[i].cmd == ops[j].cmd)
                                 return -EINVAL;
-                if (ops[i].dumpit)
-                        ops[i].flags |= GENL_CMD_CAP_DUMP;
-                if (ops[i].doit)
-                        ops[i].flags |= GENL_CMD_CAP_DO;
-                if (ops[i].policy)
-                        ops[i].flags |= GENL_CMD_CAP_HASPOL;
         }
 
         /* family is not registered yet, so no locking needed */
@@ -399,7 +394,7 @@ EXPORT_SYMBOL(__genl_register_family);
  * Return 0 on success or a negative error code.
  */
 int __genl_register_family_with_ops(struct genl_family *family,
-        struct genl_ops *ops, size_t n_ops)
+        const struct genl_ops *ops, size_t n_ops)
 {
         int err;
 
@@ -479,7 +474,8 @@ EXPORT_SYMBOL(genlmsg_put);
 
 static int genl_lock_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
 {
-        struct genl_ops *ops = cb->data;
+        /* our ops are always const - netlink API doesn't propagate that */
+        const struct genl_ops *ops = cb->data;
         int rc;
 
         genl_lock();
@@ -490,7 +486,8 @@ static int genl_lock_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
 
 static int genl_lock_done(struct netlink_callback *cb)
 {
-        struct genl_ops *ops = cb->data;
+        /* our ops are always const - netlink API doesn't propagate that */
+        const struct genl_ops *ops = cb->data;
         int rc = 0;
 
         if (ops->done) {
@@ -505,7 +502,7 @@ static int genl_family_rcv_msg(struct genl_family *family,
                                struct sk_buff *skb,
                                struct nlmsghdr *nlh)
 {
-        struct genl_ops *ops;
+        const struct genl_ops *ops;
         struct net *net = sock_net(skb->sk);
         struct genl_info info;
         struct genlmsghdr *hdr = nlmsg_data(nlh);
@@ -537,7 +534,8 @@ static int genl_family_rcv_msg(struct genl_family *family,
                 if (!family->parallel_ops) {
                         struct netlink_dump_control c = {
                                 .module = family->module,
-                                .data = ops,
+                                /* we have const, but the netlink API doesn't */
+                                .data = (void *)ops,
                                 .dump = genl_lock_dumpit,
                                 .done = genl_lock_done,
                         };
@@ -669,14 +667,22 @@ static int ctrl_fill_info(struct genl_family *family, u32 portid, u32 seq,
 
                 for (i = 0; i < family->n_ops; i++) {
                         struct nlattr *nest;
-                        struct genl_ops *ops = &family->ops[i];
+                        const struct genl_ops *ops = &family->ops[i];
+                        u32 flags = ops->flags;
+
+                        if (ops->dumpit)
+                                flags |= GENL_CMD_CAP_DUMP;
+                        if (ops->doit)
+                                flags |= GENL_CMD_CAP_DO;
+                        if (ops->policy)
+                                flags |= GENL_CMD_CAP_HASPOL;
 
                         nest = nla_nest_start(skb, i + 1);
                         if (nest == NULL)
                                 goto nla_put_failure;
 
                         if (nla_put_u32(skb, CTRL_ATTR_OP_ID, ops->cmd) ||
-                            nla_put_u32(skb, CTRL_ATTR_OP_FLAGS, ops->flags))
+                            nla_put_u32(skb, CTRL_ATTR_OP_FLAGS, flags))
                                 goto nla_put_failure;
 
                         nla_nest_end(skb, nest);