Re: [PATCH 2/2] Use num_possible_cpus() instead of direct use of NR_CPUS.

From: Vlastimil Babka
Date: Mon Jan 11 2016 - 08:46:31 EST


On 01/10/2016 04:13 PM, Ameen wrote:
> WARNING: usage of NR_CPUS is often wrong - consider using cpu_possible(), num_possible_cpus()..

Is that a checkpatch warning? Notice the word "often". You need to provide info
why it's the case here (and I doubt the change will be corect in this case).

> Signed-off-by : Ameen Ali <Ameenali023@xxxxxxxxx>
> ---
> kernel/smp.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/smp.c b/kernel/smp.c
> index d903c02..94033ac 100644
> --- a/kernel/smp.c
> +++ b/kernel/smp.c
> @@ -549,13 +549,13 @@ static int __init maxcpus(char *str)
> early_param("maxcpus", maxcpus);
>
> /* Setup number of possible processor ids */
> -int nr_cpu_ids __read_mostly = NR_CPUS;
> +int nr_cpu_ids __read_mostly = num_possible_cpus();
> EXPORT_SYMBOL(nr_cpu_ids);
>
> /* An arch may set nr_cpu_ids earlier if needed, so this would be redundant */
> void __init setup_nr_cpu_ids(void)
> {
> - nr_cpu_ids = find_last_bit(cpumask_bits(cpu_possible_mask),NR_CPUS) + 1;
> + nr_cpu_ids = find_last_bit(cpumask_bits(cpu_possible_mask),num_possible_cpus()) + 1;
> }
>
> void __weak smp_announce(void)
>