Re: [PATCH v1 01/10] cpufreq: Reference count policy in cpufreq_update_limits()

[Marek Marczykowski-Górecki]

On Fri, Mar 28, 2025 at 09:39:08PM +0100, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> 
> 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
> Reporetd-by: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>

Reported

I wanted to propose also Tested-by tag, but technically it's not me who
tested it: https://forum.qubes-os.org/t/kernel-latest-6-13-6-boot-loop/32926/18

> Cc: All applicable <stable@xxxxxxxxxxxxxxx>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> ---
>  drivers/cpufreq/cpufreq.c |    6 ++++++
>  1 file changed, 6 insertions(+)
> 
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -2781,6 +2781,12 @@
>   */
>  void cpufreq_update_limits(unsigned int cpu)
>  {
> +	struct cpufreq_policy *policy __free(put_cpufreq_policy);
> +
> +	policy = cpufreq_cpu_get(cpu);
> +	if (!policy)
> +		return;
> +
>  	if (cpufreq_driver->update_limits)
>  		cpufreq_driver->update_limits(cpu);
>  	else
> 
> 
> 

-- 
Best Regards,
Marek Marczykowski-Górecki
Invisible Things Lab

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