[PATCH 15/17] kernel/cpu: add num_active_cpu counter

[Peter Zijlstra]

On Sat, Dec 18, 2021 at 01:20:11PM -0800, Yury Norov wrote:
> Similarly to the online cpus, the cpu_active_mask is actively used
> in the kernel. This patch adds a counter for active cpus, so that
> users that call num_active_cpus() would know the result immediately,
> instead of calling the bitmap_weight for the mask.

Who cares about num_active_cpus() ?

> +EXPORT_SYMBOL(set_cpu_active);

NAK, this should *never*ever* be used from a module.