On Thu, Sep 6, 2018 at 3:59 AM Al Viro <v...@zeniv.linux.org.uk> wrote:
>
> diff --git a/net/sched/cls_u32.c b/net/sched/cls_u32.c
> index 3f985f29ef30..d14048e38b5c 100644
> --- a/net/sched/cls_u32.c
> +++ b/net/sched/cls_u32.c
> @@ -84,6 +84,7 @@ struct tc_u_hnode {
> int refcnt;
> unsigned int divisor;
> struct idr handle_idr;
> + bool is_root;
> struct rcu_head rcu;
> u32 flags;
> /* The 'ht' field MUST be the last field in structure to allow for
> @@ -377,6 +378,7 @@ static int u32_init(struct tcf_proto *tp)
> root_ht->refcnt++;
> root_ht->handle = tp_c ? gen_new_htid(tp_c, root_ht) : 0x80000000;
> root_ht->prio = tp->prio;
> + root_ht->is_root = true;
> idr_init(&root_ht->handle_idr);
>
> if (tp_c == NULL) {
> @@ -693,7 +695,7 @@ static int u32_delete(struct tcf_proto *tp, void *arg,
> bool *last,
> goto out;
> }
>
> - if (root_ht == ht) {
> + if (ht->is_root) {
What's wrong with comparing pointers with root ht?
> 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.
