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Date: Tue, 8 Sep 2026 15:25:13 +0200
From: Florian Westphal <fw@strlen.de>
To: Herbert Xu <herbert@gondor.apana.org.au>
Cc: netfilter-devel@vger.kernel.org, kadlec@netfilter.org,
	linux-crypto@vger.kernel.org
Subject: Re: [PATCH nf-next v4 01/13] rhashtable: add
 rhashtable_flush_and_free helper
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In-Reply-To: <aqACH2VVNGmgW-5B@gondor.apana.org.au>

Herbert Xu <herbert@gondor.apana.org.au> wrote:
> > No, remove all elements. Concurrent insertion is not disabled.
> 
> So what's the desired semantics for insertions that occur while
> you're flushing the table?

In current ipset home-grown hashes:

If the insertion is into a region not yet scanned -> will be dropped
If the insertion is into a region already scanned -> will exist after flush.

i.e. no guarantee that table is empty after flush, but all
elements that existed before the flush are gone.

For the rhashtable variant I had proposed:

If the insertion is before the moment future_tbl is updated: will be dropped
If the insertion is after future_tbl update: will exist after flush

which I think is matches existing semantics of ipsets homegrown hash
tables (that I'd like to replace with rhashtable/rhltable).

Thanks,
Florian