Thu, Jul 26, 2018 at 09:38:39AM CEST, j...@resnulli.us wrote: >Wed, Jul 25, 2018 at 06:40:44PM CEST, xiyou.wangc...@gmail.com wrote: >>On Tue, Jul 24, 2018 at 11:49 PM Jiri Pirko <j...@resnulli.us> wrote: >>> >>> Wed, Jul 25, 2018 at 01:20:08AM CEST, xiyou.wangc...@gmail.com wrote: >>> >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? >> >>_If_ RTM_DELCHAIN does decrease the chain refcnt, then it is >>broken: >> >># tc chain add X... (refcnt == 1) >># tc action add ... goto chain X (refcnt==2) >># tc chain del X ... (refcnt== 1) >># tc chain del X ... (refcnt==0) >> >>RTM_DELCHAIN should just test if refcnt is 1, if it is, delete it, >>otherwise return -EPERM. This is how we handle tc standalone >>actions, see tcf_idr_delete_index(). >> >>Yes, you might need two refcnt's here. > >Okay. Sounds good. I'm on it.
Actually, I found an issue. The action to "goto chain" might be attached to a filter in the same chain. That is completely legitimate usage. When I do: # tc chain del X I expect the chain to be flushed and removed. If there is an action there with "goto" to the same chain, the command should be successful. However, I don't see any easy way to find out if the chain is referenced only by actions used by filters in the same chain :/ Thoughts?
