[PATCH v3 5/5] phy: qcom: snps-femto-v2: Fix possible NULL-deref on early runtime suspend

[Loic Poulain]

Hi Johan,

On Fri, Feb 13, 2026 at 10:07 AM Johan Hovold <johan at kernel.org> wrote:
>
> On Thu, Feb 05, 2026 at 05:02:40PM +0100, Loic Poulain wrote:
> > Enabling runtime PM before attaching the hsphy instance as driver data
> > can lead to a NULL pointer dereference in runtime PM callbacks that
> > expect valid driver data. There is a small window where the suspend
> > callback may run after PM runtime enabling and before runtime forbid.
>
> So here too, the commit should reflect that this cannot really happen in
> practice.

This happened  in practice in the qcom‑qusb2 PHY driver, with the same
code flow.
Bug: https://github.com/qualcomm-linux/qcom-deb-images/issues/208
Patch: https://lore.kernel.org/linux-arm-msm/20251219085640.114473-1-loic.poulain@oss.qualcomm.com/

I know it may sound unlikely, but this crash has been reported
several times during boot‑stress testing. I haven’t investigated
deeply enough to determine whether it’s caused by an unfortunate
preemption window or a racing CPU.

I thought the series was already fairly conservative in its wording.
The titles use terms like “possible” and “unnecessary” to qualify the
crashes or unintended events. I can switch to “unlikely” if that
better characterizes the situation, but the issue isn’t purely
hypothetical.

Regards,
Loic