Re: [PATCH 2/7] mark root hnode explicitly

On Thu, Sep 06, 2018 at 07:57:25PM -0700, Cong Wang wrote:

quoted

-       if (root_ht == ht) {
+       if (ht->is_root) {

What's wrong with comparing pointers with root ht?

The fact that there may be more than one tcf_proto sharing tp->data.

quoted

                NL_SET_ERR_MSG_MOD(extack, "Not allowed to delete root node");
                return -EINVAL;
        }

@@ -795,6 +797,10 @@ static int u32_set_parms(struct net *net, struct tcf_proto *tp,
                                NL_SET_ERR_MSG_MOD(extack, "Link hash table not found");
                                return -EINVAL;
                        }
+                       if (ht_down->is_root) {

root ht is saved in tp->root, so you can compare ht_down with it too,
if you want.

If this check is all what you need, you don't need an extra flag.

Again, *which* tp?  We can trivially check that we are not linking to/deleting
our own root, sure.  But there's nothing to stop doing the same via another
tcf_proto...