Re: [PATCH] x86, apic: Do not increment disabled_cpus from generic_processor_info.

Cyrill Gorcunov
2011-01-09T11:44:17Z

On 01/09/2011 12:39 PM, Ingo Molnar wrote:
>
> * Rakib Mullick <rakib.mullick@gmail.com> wrote:
>
>> disabled_cpus has been incremented from the call path of
>> generic_processor_info (i.e from acpi_register_lapic and
>> MP_processor_info) when a perticular cpu is not enabled. So, we can
>> remove the redundant increment of disabled_cpus from
>> generic_processor_info.
>>
>>
>> Signed-off-by: Rakib Mullick <rakib.mullick@gmail.com>
...
> Hm, what effects does this have in practice? smpboot.c uses disabled_cpus as a value
> to calculate limits - why has this bug not caused some misbehavior somewhere? (or if
> it has caused misbehavior, what is that?)
>
> Thanks,
>
> Ingo

This disabled cpu may happen if nr_cpus early param specified and it's less than
nr_cpu_ids, but cpu might still be enabled in mp/acpi so we have to disable it.
And if we will not increment disabled_cpus this will lead the further report
about disabled cpu would refer to wrong cpu number. So I don't see why we
need to remove this disabled_cpus increment here.

Rakib is there something I miss?

--
Cyrill