[PATCH net-next] net: rules: Move l3mdev attribute validation to a helper

[David Ahern]

Move the check on FRA_L3MDEV attribute to helper to improve the
readability of fib_nl2rule. Update the extack messages to be
clear when the configuration option is disabled versus an invalid
value has been passed.

Signed-off-by: David Ahern <dsah...@gmail.com>
---
 net/core/fib_rules.c | 34 ++++++++++++++++++++++++----------
 1 file changed, 24 insertions(+), 10 deletions(-)

diff --git a/net/core/fib_rules.c b/net/core/fib_rules.c
index 2271c80fd967..126ffc5bc630 100644
--- a/net/core/fib_rules.c
+++ b/net/core/fib_rules.c
@@ -454,6 +454,27 @@ static struct fib_rule *rule_find(struct fib_rules_ops 
*ops,
        return NULL;
 }
 
+#ifdef CONFIG_NET_L3_MASTER_DEV
+static int fib_nl2rule_l3mdev(struct nlattr *nla, struct fib_rule *nlrule,
+                             struct netlink_ext_ack *extack)
+{
+       nlrule->l3mdev = nla_get_u8(nla);
+       if (nlrule->l3mdev != 1) {
+               NL_SET_ERR_MSG(extack, "Invalid l3mdev attribute");
+               return -1;
+       }
+
+       return 0;
+}
+#else
+static int fib_nl2rule_l3mdev(struct nlattr *nla, struct fib_rule *nlrule,
+                             struct netlink_ext_ack *extack)
+{
+       NL_SET_ERR_MSG(extack, "l3mdev support is not enabled in kernel");
+       return -1;
+}
+#endif
+
 static int fib_nl2rule(struct sk_buff *skb, struct nlmsghdr *nlh,
                       struct netlink_ext_ack *extack,
                       struct fib_rules_ops *ops,
@@ -536,16 +557,9 @@ static int fib_nl2rule(struct sk_buff *skb, struct 
nlmsghdr *nlh,
                nlrule->tun_id = nla_get_be64(tb[FRA_TUN_ID]);
 
        err = -EINVAL;
-       if (tb[FRA_L3MDEV]) {
-#ifdef CONFIG_NET_L3_MASTER_DEV
-               nlrule->l3mdev = nla_get_u8(tb[FRA_L3MDEV]);
-               if (nlrule->l3mdev != 1)
-#endif
-               {
-                       NL_SET_ERR_MSG(extack, "Invalid l3mdev");
-                       goto errout_free;
-               }
-       }
+       if (tb[FRA_L3MDEV] &&
+           fib_nl2rule_l3mdev(tb[FRA_L3MDEV], nlrule, extack) < 0)
+               goto errout_free;
 
        nlrule->action = frh->action;
        nlrule->flags = frh->flags;
-- 
2.11.0