[Bug 93294] [BAT SKL] lockdep splat

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=93294

--- Comment #8 from Joonas Lahtinen <joonas.lahtinen at linux.intel.com> ---
OK, found the real cause. P-state init ends up locking first the policy->rwsem
and then the cpu_hotplug.lock. I just wonder how this does not happen on all
platforms?

I attached a description of the call traces. I think our P-state driver should
not call get_online_cpus() during the policy init, if possible, as not many of
the other drivers call it either.

Or doing the init under cpu_hotplug_begin(). I'll see about this tomorrow.

$ fgrep get_online_cpus *
acpi-cpufreq.c:    get_online_cpus();
cpufreq.c:    get_online_cpus();
cpufreq.c:    get_online_cpus();
cpufreq.c:    get_online_cpus();
cpufreq_ondemand.c:    get_online_cpus();
intel_pstate.c:    get_online_cpus();
intel_pstate.c:    get_online_cpus();
powernow-k8.c:    get_online_cpus();

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