Re: [PATCH net v1 1/1] net: usb: asix: ax88772: drop phylink use in PM to avoid MDIO runtime PM wakeups

On Tue, Sep 09, 2025 at 04:56:45PM -0700, Jakub Kicinski wrote:

On Tue, 9 Sep 2025 09:17:17 +0200 Oleksij Rempel wrote:

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Fixes: e0bffe3e6894 ("net: asix: ax88772: migrate to phylink")

It does, but v5.15 (including v5.15.191 LTS) is affected as well, from 4a2c7217cd5a ("net: usb: asix: ax88772: manage PHY PM from MAC"). I think it could also use a patch, but I won't insist.

Ack, I'll try do address it later.

Any idea what the problem is there? Deadlocking on a different lock?

Yes, it is PM lock taken in MDIO access inside of PM routine. We can't reliably detect a PM context from MDIO bus read/write calls. Taking local counters or setting flags would partially work, but they all are not safe against race conditions.