RE: [PATCH v2] cpuidle: psci: Init cpuidle only for present CPUs

[Jacky Bai]

> Subject: Re: [PATCH v2] cpuidle: psci: Init cpuidle only for present CPUs
> 
> Hi Jacky,
> 
> I wasn't Cc-ed on the original patch.
> 
> I was searching to provide feedback but couldn't find one.
> 
> On Wed, Mar 05, 2025 at 02:31:57PM +0800, Yuanjie Yang wrote:
> > On Wed, Nov 20, 2024 at 06:37:49PM +0800, Jacky Bai wrote:
> > > With 'nosmp' or 'maxcpus=0' boot command line parameters, the
> > > 'cpu_present_mask' may not be the same as 'cpu_possible_mask'.
> > >
> > > In current psci cpuidle driver init, for_each_possible_cpu() is used
> > > to init the cpuidle for each possible CPU. but in drivers/base/cpu.c
> > > ->cpu_dev_register_generic(),
> > > for_each_present_cpu() is used to register cpu device for present
> > > CPUs.
> > >
> > > When boot system with 'nosmp' or 'maxcpus=0', the cpuidle driver
> > > init failed due to no valid CPU device sysfs node for non-boot CPUs.
> > >
> > > [ 0.182993] Failed to register cpuidle device for cpu1
> > >
> > > Use for_each_present_cpu() to register cpuidle only for present
> > > CPUs.
> > >
> 
> Can you reword it something like
> "
> 
> for_each_possible_cpu() is currently used to initialize cpuidle in the PSCI
> cpuidle driver.
> 
> However, in cpu_dev_register_generic(), for_each_present_cpu() is used to
> register CPU devices which means the CPU devices are only registered for
> present CPUs and not all possible CPUs.
> 
> With nosmp or maxcpus=0, only the boot CPU is present, leading to the
> failure:
> 
>   |  Failed to register cpuidle device for cpu1
> 
> Change for_each_possible_cpu() to for_each_present_cpu() in the PSCI
> cpuidle driver to ensure it only registers cpuidle devices for CPUs that are
> actually present.
> 
> "
> 
> With that, you can add:
> 
> Reviewed-by: Sudeep Holla <sudeep.holla@xxxxxxx>
> 
> Please cc Ulf Hansson <ulf.hansson@xxxxxxxxxx> as well. Either him or Rafael
> can then pick up the patch.
> 

Sorry, I should Cc you in the list. Thank you for your suggestion, I will resolve it in v3.

BR

> --
> Regards,
> Sudeep