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Date: Fri, 10 Apr 2026 13:14:53 +0200
From: Pablo Neira Ayuso <pablo@netfilter.org>
To: Florian Westphal <fw@strlen.de>
Cc: Weiming Shi <bestswngs@gmail.com>,
	"David S . Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	Phil Sutter <phil@nwl.cc>, Simon Horman <horms@kernel.org>,
	netfilter-devel@vger.kernel.org, coreteam@netfilter.org,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	Xiang Mei <xmei5@asu.edu>
Subject: Re: [PATCH nf] netfilter: nf_tables: use RCU-safe list primitives
 for basechain hook list
Message-ID: <adjbrcTOL8MLjtfh@chamomile>
References: <20260410101321.915190-2-bestswngs@gmail.com>
 <adjRiG_Bp3WpRYOz@strlen.de>
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In-Reply-To: <adjRiG_Bp3WpRYOz@strlen.de>

On Fri, Apr 10, 2026 at 12:31:36PM +0200, Florian Westphal wrote:
> Weiming Shi <bestswngs@gmail.com> wrote:
[...]
> > Replace list_move() in nft_delchain_hook() with list_del_rcu() plus an
> > intermediate pointer array, followed by synchronize_rcu() before the
> > deleted hooks' list pointers are reused to link them into the
> > transaction's private list. In the error paths, put hooks back with
> > list_add_tail_rcu() which is safe for concurrent RCU readers (they
> > either continue to the original successor or see the list head and
> > terminate the walk).
> 
> I don't understand the existing code.

I am working on an alternative fix.