5.4-stable review patch. If anyone has any objections, please let me know.
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From: Rafael J. Wysocki rafael.j.wysocki@intel.com
commit 9e4e249018d208678888bdf22f6b652728106528 upstream.
Since acpi_processor_notify() can be called before registering a cpufreq driver or even in cases when a cpufreq driver is not registered at all, cpufreq_update_limits() needs to check if a cpufreq driver is present and prevent it from being unregistered.
For this purpose, make it call cpufreq_cpu_get() to obtain a cpufreq policy pointer for the given CPU and reference count the corresponding policy object, if present.
Fixes: 5a25e3f7cc53 ("cpufreq: intel_pstate: Driver-specific handling of _PPC updates") Closes: https://lore.kernel.org/linux-acpi/Z-ShAR59cTow0KcR@mail-itl Reported-by: Marek Marczykowski-Górecki marmarek@invisiblethingslab.com Cc: All applicable stable@vger.kernel.org Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Acked-by: Viresh Kumar viresh.kumar@linaro.org Link: https://patch.msgid.link/1928789.tdWV9SEqCh@rjwysocki.net [do not use __free(cpufreq_cpu_put) in a backport] Signed-off-by: Marek Marczykowski-Górecki marmarek@invisiblethingslab.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/cpufreq/cpufreq.c | 8 ++++++++ 1 file changed, 8 insertions(+)
--- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -2531,10 +2531,18 @@ EXPORT_SYMBOL(cpufreq_update_policy); */ void cpufreq_update_limits(unsigned int cpu) { + struct cpufreq_policy *policy; + + policy = cpufreq_cpu_get(cpu); + if (!policy) + return; + if (cpufreq_driver->update_limits) cpufreq_driver->update_limits(cpu); else cpufreq_update_policy(cpu); + + cpufreq_cpu_put(policy); } EXPORT_SYMBOL_GPL(cpufreq_update_limits);