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

[Krzysztof Kozlowski]

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?

Best regards,
Krzysztof