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Date: Mon, 19 Jan 2026 01:39:44 +0100
From: Florian Westphal <fw@strlen.de>
To: Scott Mitchell <scott.k.mitch1@gmail.com>
Cc: netfilter-devel@vger.kernel.org, pablo@netfilter.org
Subject: Re: [PATCH v6 1/2] netfilter: nfnetlink_queue: nfqnl_instance
 GFP_ATOMIC -> GFP_KERNEL_ACCOUNT allocation
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References: <20260117173231.88610-1-scott.k.mitch1@gmail.com>
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Scott Mitchell <scott.k.mitch1@gmail.com> wrote:
> On Sat, Jan 17, 2026 at 2:45 PM Florian Westphal <fw@strlen.de> wrote:
> >
> > scott.k.mitch1@gmail.com <scott.k.mitch1@gmail.com> wrote:
> > > +     /* Lookup queue under RCU. After peer_portid check (or for new queue
> > > +      * in BIND case), the queue is owned by the socket sending this message.
> > > +      * A socket cannot simultaneously send a message and close, so while
> > > +      * processing this CONFIG message, nfqnl_rcv_nl_event() (triggered by
> > > +      * socket close) cannot destroy this queue. Safe to use without RCU.
> > > +      */
> >
> > Could you add a
> >
> > WARN_ON_ONCE(!lockdep_nfnl_is_held(NFNL_SUBSYS_QUEUE));
> >
> > somewhere in this function?
> >
> > Just to assert that this is serialized vs. other config messages.
> >
> > Thanks.
> 
> Will do! Does the overall approach make sense?

I don't see any problem with this patch. nfqnl_rcv_nl_event()
cannot run at same time for this socket; it would already be a
problem for the existing code, parallel event+queue unbind
would result in double-free.

So the comment makes sense to me.