From: Andrew Lunn <andrew@lunn.ch>
To: Ali Tariq <alitariq45892@gmail.com>
Cc: Troy Mitchell <troy.mitchell@linux.spacemit.com>,
Vadim Fedorenko <vadim.fedorenko@linux.dev>,
netdev@vger.kernel.org, Andrew Lunn <andrew+netdev@lunn.ch>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@kernel.org>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
Yixun Lan <dlan@kernel.org>,
Vivian Wang <wangruikang@iscas.ac.cn>,
Chukun Pan <amadeus@jmu.edu.cn>,
Siddharth Vadapalli <s-vadapalli@ti.com>,
Tomas Hlavacek <tmshlvck@gmail.com>,
Muhammad Bilal <meatuni001@gmail.com>,
Maxime Chevallier <maxime.chevallier@bootlin.com>,
linux-riscv@lists.infradead.org, spacemit@lists.linux.dev,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH net] net: spacemit: Hold RTNL lock in emac_resume() and emac_suspend()
Date: Sat, 7 Nov 2026 18:32:05 +0100 [thread overview]
Message-ID: <12a95b3a-9c8b-4a2d-9b81-12b3839e64a9@lunn.ch> (raw)
In-Reply-To: <c55c5878-d9c1-4863-bc55-99d334ba2ede@gmail.com>
On Fri, Nov 06, 2026 at 03:44:50PM +0500, Ali Tariq wrote:
>
>
> On 11/6/26 2:43 PM, Troy Mitchell wrote:
> > On Thu, 5 Nov 2026 17:34:37 +0500, Ali Tariq wrote:
> > > @@ -2056,7 +2059,9 @@ static int emac_suspend(struct device *dev)
> > > return 0;
> > > }
> > > + rtnl_lock();
> > > emac_stop(ndev);
> > > + rtnl_unlock();
> > > clk_disable_unprepare(priv->bus_clk);
> > > netif_device_detach(ndev);
> > This can deadlock. emac_stop() -> emac_down() calls
> > cancel_work_sync(&priv->tx_timeout_task) with RTNL now held, while
> > emac_tx_timeout_task() starts with rtnl_lock().
> >
>
> Thanks Troy, that makes sense.
>
> For the deadlock, I think the correct function to call is rtnl_trylock()
> inside the emac_tx_timeout_task(), which would return if the lock is already
> held and will hold the lock if it is not.
rtnl_trylock() is generally a workaround needed for badly written
code. Please try to avoid it.
Andrew
prev parent reply other threads:[~2026-11-07 17:32 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-05 12:34 Ali Tariq
2026-11-05 13:40 ` Breno Leitao
2026-11-05 22:28 ` Vadim Fedorenko
2026-11-06 9:41 ` Troy Mitchell
2026-11-06 11:54 ` Breno Leitao
2026-11-06 14:28 ` Troy Mitchell
2026-11-06 9:43 ` Troy Mitchell
2026-11-06 10:44 ` Ali Tariq
2026-11-06 14:26 ` Troy Mitchell
2026-11-07 17:32 ` Andrew Lunn [this message]
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