Re: [PATCH net-next v3] net: phy: Fix suspicious rcu_dereference usage
From: Kory Maincent <kory.maincent@bootlin.com>
Date: 2025-01-23 14:05:49
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On Thu, 23 Jan 2025 13:25:57 +0200 Claudiu Beznea [off-list ref] wrote:
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ravb_ptp_stop() modifies a couple of device registers and calls ptp_clock_unregister(). I don't see anything to suggest that this requires the rtnl lock to be held, unless I am missing something.What happens if two ptp_clock_unregister() with the same ptp_clock pointer are called simultaneously? From ravb_suspend and ravb_set_ringparam for example. It may cause some errors.Can this happen? I see ethtool_ops::set_ringparam() references only in ethtool or ioctl files: net/ethtool/ioctl.c:2066 net/ethtool/ioctl.c:2081 net/ethtool/rings.c:212 net/ethtool/rings.c:304 At the time the suspend/resume APIs are called the user space threads are frozen.
Maybe, I don't know the suspend path, and what the state of user space threads at that time. This was an example but Wake on Lan setup could also have some issue. IMHO I think it is more precautions to have it under rtnl lock. Regards, -- Köry Maincent, Bootlin Embedded Linux and kernel engineering https://bootlin.com