From: Jakub Kicinski <kuba@kernel.org>
To: Kory Maincent <kory.maincent@bootlin.com>
Cc: Eric Dumazet <edumazet@google.com>,
"David S. Miller" <davem@davemloft.net>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>,
thomas.petazzoni@bootlin.com, Andrew Lunn <andrew@lunn.ch>,
Heiner Kallweit <hkallweit1@gmail.com>,
Russell King <linux@armlinux.org.uk>,
Paolo Abeni <pabeni@redhat.com>
Subject: Re: [PATCH net-next v2] net: phy: Fix suspicious rcu_dereference usage
Date: Fri, 17 Jan 2025 19:07:20 -0800 [thread overview]
Message-ID: <20250117190720.1bb02d71@kernel.org> (raw)
In-Reply-To: <20250117231659.31a4b7fa@kmaincent-XPS-13-7390>
On Fri, 17 Jan 2025 23:16:59 +0100 Kory Maincent wrote:
> > If not protected by RTNL, what prevents two threads from calling this
> > function at the same time,
> > thus attempting to kfree_rcu() the same pointer twice ?
>
> I don't think this function can be called simultaneously from two threads,
> if this were the case we would have already seen several issues with the phydev
> pointer. But maybe I am wrong.
>
> The rcu_lock here is to prevent concurrent dev->hwprov pointer modification done
> under rtnl_lock in net/ethtool/tsconfig.c.
I could also be wrong, but I don't recall being told that suspend path
can't race with anything else. So I think ravb should probably take
rtnl_lock or some such when its shutting itself down.. ?
If I'm wrong I think we should mention this is from suspend and
add Claudiu's stack trace to the commit msg.
--
pw-bot: cr
next prev parent reply other threads:[~2025-01-18 3:07 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-01-17 17:36 [PATCH net-next v2] net: phy: Fix suspicious rcu_dereference usage Kory Maincent
2025-01-17 19:06 ` Eric Dumazet
2025-01-17 22:16 ` Kory Maincent
2025-01-18 3:07 ` Jakub Kicinski [this message]
2025-01-19 12:45 ` Kory Maincent
2025-01-19 14:27 ` Russell King (Oracle)
2025-01-19 16:27 ` Kory Maincent
2025-01-20 9:37 ` Kory Maincent
2025-01-20 10:31 ` Russell King (Oracle)
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