Re: [PATCH net] net: spacemit: Hold RTNL lock in emac_resume() and emac_suspend()

From: Breno Leitao <leitao@debian.org>
To: Troy Mitchell <troy.mitchell@linux.spacemit.com>
Cc: Vadim Fedorenko <vadim.fedorenko@linux.dev>,
	 Ali Tariq <alitariq45892@gmail.com>,
	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: Fri, 6 Nov 2026 03:54:14 -0800	[thread overview]
Message-ID: <au2_yS85zJYqOaYm@gmail.com> (raw)
In-Reply-To: <DMO12HWY5N64.2IJ5XMUKM8WWR@linux.spacemit.com>

On Fri, Nov 06, 2026 at 09:41:31AM +0000, Troy Mitchell wrote:
> On Thu, 5 Nov 2026 23:28:31 +0100, Vadim Fedorenko wrote:
> > > This would work, but I am wondering if it would be possible to call
> > > rtnl inside the _open function, when dealing with the PHY? in other
> > > words, shrink the time rtnl is held.
> >
> > +1, especially in emac_open() rtnl is needed only in error path case
> 
> emac_open() and emac_stop() are also the driver's .ndo_open and
> .ndo_stop, which the core already calls with RTNL held, see
> Documentation/networking/netdevices.rst +214. Taking rtnl_lock()
> inside them would deadlock on every open and close, so the lock has to
> stay in the PM callbacks.

That makes sense to me.

Reviewed-by: Breno Leitao <leitao@debian.org>