Re: [PATCH 00/23] interconnect: fix racy provider registration

Johan Hovold
2023-02-02T12:20:16Z

On Thu, Feb 02, 2023 at 12:13:33PM +0100, Krzysztof Kozlowski wrote:
> On 01/02/2023 11:15, Johan Hovold wrote:
> > The current interconnect provider interface is inherently racy as
> > providers are expected to be registered before being fully initialised.
> >
> > This can specifically cause racing DT lookups to fail as I recently
> > noticed when the Qualcomm cpufreq driver failed to probe:
> >
> > of_icc_xlate_onecell: invalid index 0
> > cpu cpu0: error -EINVAL: error finding src node
> > cpu cpu0: dev_pm_opp_of_find_icc_paths: Unable to get path0: -22
> > qcom-cpufreq-hw: probe of 18591000.cpufreq failed with error -22
> >
> > This only happens very rarely, but the bug is easily reproduced by
> > increasing the race window by adding an msleep() after registering
> > osm-l3 interconnect provider.
> >
> > Note that the Qualcomm cpufreq driver is especially susceptible to this
> > race as the interconnect path is looked up from the CPU nodes so that
> > driver core does not guarantee the probe order even when device links
> > are enabled (which they not always are).
> >
> > This series adds a new interconnect provider registration API which is
> > used to fix up the interconnect drivers before removing the old racy
> > API.
> >
>
> So is there a dependency or not? Can you make it clear that I shouldn't
> take memory controller bits?

As the fixes depend on the new API it is best if these could all go
through Georgi's tree.

Johan