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Re: [PATCH V6] powercap/drivers/idle_injection: Add an idle injection framework




On 12/06/2018 14:30, Peter Zijlstra wrote:
> On Tue, Jun 12, 2018 at 02:00:11PM +0200, Daniel Lezcano wrote:
>> +static void __idle_injection_wakeup(struct idle_injection_device *ii_dev)
>> +{
>> +	struct idle_injection_thread *iit;
>> +	struct cpumask tmp;
>> +	unsigned int cpu;
>> +
>> +	cpumask_and(&tmp, ii_dev->cpumask, cpu_online_mask);
> 
> You should not be having a cpumask on the stack. Those things can be
> ginormous.

Ok, the kernel code uses of cpumask_t on the stack when dealing with
cpumask_and. I assume it is also not recommended.

What would be the best practice ? Allocate a per cpumask at init time as
a temporary mask to work with ?




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