cpumask_nonempty
cpumask_t *rcmp = cpumask_nonempty(bind_readers) ? bind_readers : &cpumask_all;
cpumask_t *wcmp = cpumask_nonempty(bind_writers) ? bind_writers : &cpumask_all;
if (cpumask_nonempty(bind_writers))
if (cpumask_nonempty(bind_readers))