Thread (10 messages) 10 messages, 5 authors, 2025-09-22

Re: [PATCH net v1 1/1] net: usb: asix: forbid runtime PM to avoid PM/MDIO + RTNL deadlock

From: Oliver Neukum <oneukum@suse.com>
Date: 2025-09-17 10:10:52
Also in: linux-usb, lkml, stable

Hi,

On 17.09.25 11:54, Oleksij Rempel wrote:
With autosuspend active, resume paths may require calling phylink/phylib
(caller must hold RTNL) and doing MDIO I/O. Taking RTNL from a USB PM
resume can deadlock (RTNL may already be held), and MDIO can attempt a
runtime-wake while the USB PM lock is held. Given the lack of benefit
and poor test coverage (autosuspend is usually disabled by default in
distros), forbid runtime PM here to avoid these hazards.
This reasoning depends on netif_running() returning false during system resume.
Is that guaranteed?

	Regards
		Oliver
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