Re: [PATCH net v2 2/2] net: pse-pd: guard regulator ops against freed PI data during unregister

On Mon, 10 Aug 2026 13:52:33 -0700 Jakub Kicinski wrote:
> It'd be great if we can figure out the safe lifetime rules for pse-pd
> from all entry points. Specifically the sysfs complaint on patch 1
> (assuming it's real) makes the series seem like a bit of of a see-saw.
>
> Let's get it reposted and take it from there?

Thanks for the reviews, Kory.

Makes sense. Let me go through everything that still touches pcdev->pi
once pse_controller_unregister() has started freeing it, so it's clear
what the series covers and what it doesn't.

The regulator ops (pse_pi_enable/disable/is_enabled) are the sysfs case.
It's real: the PI regulators get registered before the controller, so on
unbind the controller goes down first and pse_release_pis() frees
pcdev->pi while the regulators are still live. is_enabled() is
reachable over sysfs. Patch 2 is what handles this - it checks !pcdev->pi
in those three ops and frees under the same lock. Patch 1 just does the
reorder, so the two really need to be read together.

The other one is of_pse_match_pi() from of_pse_control_get(). A consumer
probing at the same time walks pse_controller_list and reads
pcdev->pi[i].np. Problem is we free pi before list_del(), so the
controller is still on the list with pi already gone. The series doesn't
touch this yet. It's a one-liner really - move list_del() before the
free. Then a lookup either sees a valid pi or doesn't find the controller
at all, no NULL checks anywhere. I'd add that as a patch 3.

Last two are pse_ethtool_get_status() and __pse_control_release(), from a
consumer still holding a pse_control. They read pcdev->pi[psec->id] too,
but here the real issue isn't pi, it's that the consumer can outlive the
whole controller - of_pse_control_get() only takes a module ref, no
device link - so a NULL check buys you nothing. That's pre-existing and
not really something to fix in net. The notifier series I have for
net-next [1] is what deals with it: the phy layer drops phydev->psec on
unregister before pi is freed, and phy is the only pse_control user we
have in tree.

So for v3: patches 1 and 2 as they are with Kory's Reviewed-by, plus the
small patch 3 for the list_del reorder, and I'll write all this up in the
cover letter so the ethtool side is clearly left to [1].

Sound ok before I send it out?

[1] https://lore.kernel.org/netdev/[email protected]/

Thanks,
Carlo