From: Pablo Neira Ayuso <pablo@netfilter.org>
To: Qingfang Deng <dqfext@gmail.com>
Cc: Eric Dumazet <edumazet@google.com>,
Andrew Lunn <andrew+netdev@lunn.ch>,
"David S. Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
Felix Fietkau <nbd@nbd.name>,
linux-ppp@vger.kernel.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH net] ppp: fix race conditions in ppp_fill_forward_path
Date: Tue, 12 Aug 2025 15:02:35 +0200 [thread overview]
Message-ID: <aJs7az9VnJ6aUwQT@calendula> (raw)
In-Reply-To: <CALW65jYNMNArwzmpHhYj3fpfL0Oz2fRYsJz0JMDUnyByu-8z3w@mail.gmail.com>
On Tue, Aug 12, 2025 at 05:38:02PM +0800, Qingfang Deng wrote:
> On Mon, Aug 11, 2025 at 5:35 PM Qingfang Deng <dqfext@gmail.com> wrote:
> >
> > On Mon, Aug 11, 2025 at 5:19 PM Eric Dumazet <edumazet@google.com> wrote:
> > >
> > > On Mon, Aug 11, 2025 at 1:44 AM Qingfang Deng <dqfext@gmail.com> wrote:
> > > It is unclear if rcu_read_lock() is held at this point.
> > >
> > > list_first_or_null_rcu() does not have a builtin __list_check_rcu()
> >
> > ndo_fill_forward_path() is called by nf_tables chains, which is inside
> > an RCU critical section.
>
> Update: mtk_flow_get_wdma_info() in mtk_ppe_offload.c calls
> dev_fill_forward_path() in process context without RCU, so
> ppp_fill_forward_path() can be called from two different contexts.
> Should I add rcu_read_lock() to mtk_flow_get_wdma_info() or
> ppp_fill_forward_path()?
mtk_flow_get_wdma_info() seems to be the exception at this point, so
I'm inclined to add rcu_read_lock() to mtk_flow_get_wdma_info().
next prev parent reply other threads:[~2025-08-12 13:02 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-08-11 8:44 [PATCH net] ppp: fix race conditions in ppp_fill_forward_path Qingfang Deng
2025-08-11 9:19 ` Eric Dumazet
2025-08-11 9:35 ` Qingfang Deng
2025-08-12 9:38 ` Qingfang Deng
2025-08-12 13:02 ` Pablo Neira Ayuso [this message]
2025-08-13 1:46 ` Qingfang Deng
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