nexthop: Factor out neighbor validity check

For legacy nexthops, there is fib_good_nh() to check the neighbor validity.
In order to make the nexthop object code more similar to the legacy nexthop
code, factor out the nexthop object neighbor validity check into its own
function.
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Benjamin Poirier <bpoirier@nvidia.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20230719-nh_select-v2-2-04383e89f868@nvidia.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

net/ipv4/nexthop.c

@@ -1152,6 +1152,20 @@ static bool ipv4_good_nh(const struct fib_nh *nh)
 	return !!(state & NUD_VALID);
 }
 
+static bool nexthop_is_good_nh(const struct nexthop *nh)
+{
+	struct nh_info *nhi = rcu_dereference(nh->nh_info);
+
+	switch (nhi->family) {
+	case AF_INET:
+		return ipv4_good_nh(&nhi->fib_nh);
+	case AF_INET6:
+		return ipv6_good_nh(&nhi->fib6_nh);
+	}
+
+	return false;
+}
+
 static struct nexthop *nexthop_select_path_fdb(struct nh_group *nhg, int hash)
 {
 	int i;
@@ -1179,26 +1193,15 @@ static struct nexthop *nexthop_select_path_hthr(struct nh_group *nhg, int hash)
 
 	for (i = 0; i < nhg->num_nh; ++i) {
 		struct nh_grp_entry *nhge = &nhg->nh_entries[i];
-		struct nh_info *nhi;
 
 		if (hash > atomic_read(&nhge->hthr.upper_bound))
 			continue;
 
-		nhi = rcu_dereference(nhge->nh->nh_info);
-
 		/* nexthops always check if it is good and does
 		 * not rely on a sysctl for this behavior
 		 */
-		switch (nhi->family) {
-		case AF_INET:
-			if (ipv4_good_nh(&nhi->fib_nh))
+		if (nexthop_is_good_nh(nhge->nh))
 			return nhge->nh;
-			break;
-		case AF_INET6:
-			if (ipv6_good_nh(&nhi->fib6_nh))
-				return nhge->nh;
-			break;
-		}
 
 		if (!rc)
 			rc = nhge->nh;