Thu, Jul 26, 2018 at 12:06:14PM CEST, j...@resnulli.us wrote: >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?
I'm now working on a patch that would treat empty chains implicitly created or deleted by user that only are referenced by action as a zombie ones. They won't be visible on dump. User won't know about them, they would only serve as a place holder for "goto chain" actions. I think it is reasonable. What do you think. Will send the RFC in few hours. >
