Export group_cpus_evenly() so that some modules
can make use of it to group CPUs evenly according
to NUMA and CPU locality.

Signed-off-by: Xie Yongji <xieyongji@bytedance.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20230323053043.35-2-xieyongji@bytedance.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

allnoconfig grew these new build warnings in lib/group_cpus.c:

  lib/group_cpus.c:247:12: warning: ‘__group_cpus_evenly’ defined but not used [-Wunused-function]
  lib/group_cpus.c:75:13: warning: ‘build_node_to_cpumask’ defined but not used [-Wunused-function]
  lib/group_cpus.c:66:13: warning: ‘free_node_to_cpumask’ defined but not used [-Wunused-function]
  lib/group_cpus.c:43:23: warning: ‘alloc_node_to_cpumask’ defined but not used [-Wunused-function]

Widen the #ifdef CONFIG_SMP block to not expose unused helpers on
non-SMP builds.

Also annotate the preprocessor branches for better readability.

Fixes: f7b3ea8cf72f ("genirq/affinity: Move group_cpus_evenly() into lib/")
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20221227022905.352674-6-ming.lei@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

group_cpus_evenly() has become a generic function which can be used for
other subsystems than the interrupt subsystem, so move it into lib/.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jens Axboe <axboe@kernel.dk>                                                                                                                                                                                                    
Link: https://lore.kernel.org/r/20221227022905.352674-6-ming.lei@redhat.com