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Date:   Tue, 3 Oct 2023 11:42:43 +0200
From:   Pablo Neira Ayuso <pablo@netfilter.org>
To:     Florian Westphal <fw@strlen.de>
Cc:     netfilter-devel@vger.kernel.org
Subject: Re: update element timeout support [was Re: [PATCH nf 1/2]
 netfilter: nft_set_rbtree: move sync GC from insert path to
 set->ops->commit]
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On Tue, Oct 03, 2023 at 11:04:10AM +0200, Florian Westphal wrote:
> Pablo Neira Ayuso <pablo@netfilter.org> wrote:
> > Hi Florian,
> > 
> > I am collecting here your comments for the model we are defining for
> > set elements:
> > 
> > https://people.netfilter.org/pablo/setelems-timeout.txt
> 
> LGTM.  I think your proposal to snapshot current time and
> remove the "moving target" is key.

Agreed.

> > Let me know if you have more possible scenarios that you think that
> > might not be address by this model:
> > 
> > - Annotate current time at the beginning of the transaction, use it
> >   in _expired() check (=> timeout is not a moving target anymore).
> > - Annotate element timeout update in transaction, update timeout from
> >   _commit() path not to refresh it.
> 
> Right, I think that will work.
> For rbtree, sync gc is kept in place, elements are not zapped,
> they get tagged as DEAD, including the end element.
> 
> Then from commit, do full scan and remove any and all elements
> that are flagged as DEAD or have expired.

Sounds good.

Would you follow this approach to fix the existing issue with the
rbtree on-demand GC in nf.git?