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

Ingo Molnar
2011-01-09T09:39:40Z

* 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>
> ---
>
> diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
> index ce65d44..2499664 100644
> --- a/arch/x86/kernel/apic/apic.c
> +++ b/arch/x86/kernel/apic/apic.c
> @@ -1943,7 +1943,6 @@ void __cpuinit generic_processor_info(int
> apicid, int version)
> "ACPI: NR_CPUS/possible_cpus limit of %i reached."
> " Processor %d/0x%x ignored.\n", max, thiscpu, apicid);
>
> - disabled_cpus++;
> return;

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