[PATCH v2 0/5] cpumask: cleanup nr_cpu_ids vs nr_cpumask_bits mess

[Yury Norov <yury.norov@gmail.com>]

cpumask subsystem uses nr_cpu_ids and nr_cpumask_bits interchangeably
despite that the variables have different meaning and purpose. It makes
some cpumask functions broken.

This series cleans that mess and adds new config FORCE_NR_CPUS that
allows to optimize cpumask subsystem if the number of CPUs is known
at compile-time.

After some testing I found build broken when SMP is on and NR_CPUS == 1.
This is addressed in a new patch #1, and in the following patch #2 that
now declares set_nr_cpu_ids in cpumask.h (was in smp.h).

v1: https://lore.kernel.org/lkml/20220829165748.1008477-1-yury.norov@gmail.com/T/#mecbd787f8d1bff1454a4ec2fe46ad6dc168df695
v2:
 - don't declare nr_cpu_ids if NR_CPUS == 1;
 - move set_nr_cpu_ids() from smp.h to cpumask.h to avoid errors in some
   inclusion paths;
 - drop 'default n' in FORCE_NR_CPUS option description;
 - rebase on top of v6.0-rc4.

Yury Norov (5):
  smp: don't declare nr_cpu_ids if NR_CPUS == 1
  smp: add set_nr_cpu_ids()
  lib/cpumask: delete misleading comment
  lib/cpumask: deprecate nr_cpumask_bits
  lib/cpumask: add FORCE_NR_CPUS config option

 arch/loongarch/kernel/setup.c |  2 +-
 arch/mips/kernel/setup.c      |  2 +-
 arch/x86/kernel/smpboot.c     |  4 ++--
 arch/x86/xen/smp_pv.c         |  2 +-
 include/linux/cpumask.h       | 22 +++++++++++-----------
 kernel/smp.c                  |  6 ++++--
 lib/Kconfig                   |  9 +++++++++
 7 files changed, 29 insertions(+), 18 deletions(-)

-- 
2.34.1