Wed, Jul 25, 2018 at 01:20:08AM CEST, xiyou.wangc...@gmail.com wrote:
>On Tue, Jul 24, 2018 at 3:30 PM Cong Wang <xiyou.wangc...@gmail.com> wrote:
>>
>> On Mon, Jul 23, 2018 at 12:25 AM Jiri Pirko <j...@resnulli.us> wrote:
>> > + switch (n->nlmsg_type) {
>> > + case RTM_NEWCHAIN:
>> > + /* In case the chain was successfully added, take a
>> > reference
>> > + * to the chain. This ensures that an empty chain
>> > + * does not disappear at the end of this function.
>> > + */
>> > + tcf_chain_hold(chain);
>> > + chain->explicitly_created = true;
>> > + tc_chain_notify(chain, NULL, 0, NLM_F_CREATE | NLM_F_EXCL,
>> > + RTM_NEWCHAIN, false);
>> > + break;
>> > + case RTM_DELCHAIN:
>> > + /* Flush the chain first as the user requested chain
>> > removal. */
>> > + tcf_chain_flush(chain);
>> > + /* In case the chain was successfully deleted, put a
>> > reference
>> > + * to the chain previously taken during addition.
>> > + */
>> > + tcf_chain_put_explicitly_created(chain);
>> > + break;
>>
>> I don't see you send notification to user-space when deleting a chain,
>> am I missing anything?
>
>Oh, it is hidden in tcf_chain_put():
>
>void tcf_chain_put(struct tcf_chain *chain)
>{
> if (--chain->refcnt == 0) {
> tc_chain_notify(chain, NULL, 0, 0, RTM_DELCHAIN, false);
> tc_chain_tmplt_del(chain);
> tcf_chain_destroy(chain);
> }
>}
>
>So, you only send out notification when the last refcnt is gone.
>
>If the chain that is being deleted by a user is still used by an action,
>you return 0 or -EPERM?
0 and the chain stays there until the action is removed. Hmm, do you thing
that -EPERM should be returned in that case? The thing is, we have to
flush the chain in order to see the action references are there. We would
have to have 2 ref counters, one for filter, one for actions.
What do you think?
