powerpc/smp: Depend on cpu_l1_cache_map when adding CPUs

Currently on hotplug/hotunplug, CPU iterates through all the CPUs in
its core to find threads in its thread group. However this info is
already captured in cpu_l1_cache_map. Hence reduce iterations and
cleanup add_cpu_to_smallcore_masks function.

Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Tested-by: Satheesh Rajendran <sathnaga@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200921095653.9701-8-srikar@linux.vnet.ibm.com

diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index 0e96f6687363ba7d37bcfb257023f4383535ab3c..3a3e6bbab29c2e651988aaa07ecef82354466af1 100644 (file)
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -1285,16 +1285,15 @@ static void remove_cpu_from_masks(int cpu)
 
 static inline void add_cpu_to_smallcore_masks(int cpu)
 {
-       struct cpumask *this_l1_cache_map = per_cpu(cpu_l1_cache_map, cpu);
-       int i, first_thread = cpu_first_thread_sibling(cpu);
+       int i;
 
        if (!has_big_cores)
                return;
 
        cpumask_set_cpu(cpu, cpu_smallcore_mask(cpu));
 
-       for (i = first_thread; i < first_thread + threads_per_core; i++) {
-               if (cpu_online(i) && cpumask_test_cpu(i, this_l1_cache_map))
+       for_each_cpu(i, per_cpu(cpu_l1_cache_map, cpu)) {
+               if (cpu_online(i))
                        set_cpus_related(i, cpu, cpu_smallcore_mask);
        }
 }