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Date: Fri, 25 Oct 2024 01:22:30 +0200
From: Florian Westphal <fw@strlen.de>
To: Pablo Neira Ayuso <pablo@netfilter.org>
Cc: Matthieu Baerts <matttbe@kernel.org>, netfilter-devel@vger.kernel.org,
	Jozsef Kadlecsik <kadlec@netfilter.org>,
	Florian Westphal <fw@strlen.de>, Phil Sutter <phil@nwl.cc>,
	coreteam@netfilter.org
Subject: Re: Netfilter: suspicious RCU usage in __nft_rule_lookup
Message-ID: <20241024232230.GA23717@breakpoint.cc>
References: <da27f17f-3145-47af-ad0f-7fd2a823623e@kernel.org>
 <ZxqKkVCnyOqHjFq-@calendula>
 <ZxqQAIlQx8C1E6FK@calendula>
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Pablo Neira Ayuso <pablo@netfilter.org> wrote:
> 
> this comment below is also not valid anymore:
> 
> /* called with rcu_read_lock held */
> static struct sk_buff *
> nf_tables_getrule_single(u32 portid, const struct nfnl_info *info,
>                          const struct nlattr * const nla[], bool reset)

Yes, either called with rcu read lock or commit mutex held.

> This is not the only spot that can trigger rcu splats.

Agree.  Will you make a patch or should I take a look?
I'm leaning towards a common helper that can pass the
right lockdep annotation, i.e. pass nft_net as arg to
document when RCU or transaction semantics apply.