drivers: vxlan: vnifilter: free percpu vni stats on error path

In case rhashtable_lookup_insert_fast() fails inside vxlan_vni_add(), the
allocated percpu vni stats are not freed on the error path.

Introduce vxlan_vni_free() which would work as a nice wrapper to free
vxlan_vni_node resources properly.

Found by Linux Verification Center (linuxtesting.org).

Fixes: 4095e0e ("drivers: vxlan: vnifilter: per vni stats")
Suggested-by: Ido Schimmel <idosch@idosch.org>
Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>

Author: pchelkin91

drivers/net/vxlan/vxlan_vnifilter.c

@@ -713,6 +713,12 @@ static struct vxlan_vni_node *vxlan_vni_alloc(struct vxlan_dev *vxlan,
 	return vninode;
 }
 
+static void vxlan_vni_free(struct vxlan_vni_node *vninode)
+{
+	free_percpu(vninode->stats);
+	kfree(vninode);
+}
+
 static int vxlan_vni_add(struct vxlan_dev *vxlan,
 			 struct vxlan_vni_group *vg,
 			 u32 vni, union vxlan_addr *group,
@@ -740,7 +746,7 @@ static int vxlan_vni_add(struct vxlan_dev *vxlan,
 					    &vninode->vnode,
 					    vxlan_vni_rht_params);
 	if (err) {
-		kfree(vninode);
+		vxlan_vni_free(vninode);
 		return err;
 	}
 
@@ -763,8 +769,7 @@ static void vxlan_vni_node_rcu_free(struct rcu_head *rcu)
 	struct vxlan_vni_node *v;
 
 	v = container_of(rcu, struct vxlan_vni_node, rcu);
-	free_percpu(v->stats);
-	kfree(v);
+	vxlan_vni_free(v);
 }
 
 static int vxlan_vni_del(struct vxlan_dev *vxlan,