On Fri, Jun 12, 2015 at 11:17:08AM -0700, Vikas Shivappa wrote:
> There is currently no cpumask helper function to pick a "random" cpu
> from a mask which is also online.
>
> cpumask_any_online_but() does that which is similar to cpumask_any_but()
> but also returns a cpu that is online.
>
> Signed-off-by: Vikas Shivappa <vikas.shiva...@linux.intel.com>
> ---
> include/linux/cpumask.h | 18 ++++++++++++++++++
> 1 file changed, 18 insertions(+)
>
> diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
> index 27e285b..f2d7e8a 100644
> --- a/include/linux/cpumask.h
> +++ b/include/linux/cpumask.h
> @@ -548,6 +548,24 @@ static inline void cpumask_copy(struct cpumask *dstp,
> #define cpumask_of(cpu) (get_cpu_mask(cpu))
>
> /**
> + * cpumask_any_online_but - return a "random" and online cpu in a cpumask,
> + * but not this one
> + * @mask: the input mask to search
> + * @cpu: the cpu to ignore
> + *
> + * Returns >= nr_cpu_ids if no cpus set.
> +*/
> +static inline unsigned int cpumask_any_online_but(const struct cpumask *mask,
> + unsigned int cpu)
> +{
> + cpumask_t tmp;
No, you cannot put a cpumask_t on stack like that. Those things can be
massive.
> +
> + cpumask_and(&tmp, cpu_online_mask, mask);
> + cpumask_clear_cpu(cpu, &tmp);
> + return cpumask_any(&tmp);
> +}
You had a good example in cpumask_any_but() copy that.
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