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Date:   Thu, 28 Sep 2023 21:21:27 +0200
From:   Florian Westphal <fw@strlen.de>
To:     Pablo Neira Ayuso <pablo@netfilter.org>
Cc:     Florian Westphal <fw@strlen.de>, Phil Sutter <phil@nwl.cc>,
        netfilter-devel@vger.kernel.org
Subject: Re: [nf PATCH v2 8/8] netfilter: nf_tables: Add locking for
 NFT_MSG_GETSETELEM_RESET requests
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Pablo Neira Ayuso <pablo@netfilter.org> wrote:
> > I'd say its semantically the same thing, we alter state.
> > 
> > We even emit audit records to tell userspace that there is state
> > change.
> 
> This is a netlink event, how does the mutex help in that regard?

It will prevent two concurrent 'reset dumps' from messing
up internal state of counters, quota, etc.

> > Also, are you sure spinlock is appropriate here?
> > 
> > For full-ruleset resets we might be doing quite some
> > traverals.
> 
> I said several times, we grab and release this for each
> netlink_recvmsg(), commit_mutex helps us in no way to fix the "two
> concurrent dump-and-reset problem".

It does, any lock prevents the 'concurrent reset problem'.