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arm64: topology: restrict updating siblings_masks to online cpus only

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It's incorrect to iterate over all the possible CPUs to update the
sibling masks when any CPU is hotplugged in. In case the topology
siblings masks of the CPU is removed when is it hotplugged out, we
end up updating those masks when one of it's sibling is powered up
again. This will provide inconsistent view.

Further, since the CPU calling update_sibling_masks is yet to be set
online, there's no need to compare itself with each online CPU when
updating the siblings masks.

This patch restricts updation of sibling masks only for CPUs that are
already online. It also the drops the unnecessary cpuid check.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Tested-by: Ganapatrao Kulkarni <ganapatrao.kulkarni@cavium.com>
Tested-by: Hanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Sudeep Holla 2018-07-06 12:02:45 +01:00 committed by Will Deacon
parent 5bdd2b3f0f
commit 5ec8b59172
1 changed files with 3 additions and 5 deletions
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8
arch/arm64/kernel/topology.c
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@ -231,7 +231,7 @@ static void update_siblings_masks(unsigned int cpuid)
int cpu;
/* update core and thread sibling masks */
for_each_possible_cpu(cpu) {
for_each_online_cpu(cpu) {
cpu_topo = &cpu_topology[cpu];
if (cpuid_topo->llc_id == cpu_topo->llc_id) {
@ -243,15 +243,13 @@ static void update_siblings_masks(unsigned int cpuid)
continue;
cpumask_set_cpu(cpuid, &cpu_topo->core_sibling);
if (cpu != cpuid)
cpumask_set_cpu(cpu, &cpuid_topo->core_sibling);
cpumask_set_cpu(cpu, &cpuid_topo->core_sibling);
if (cpuid_topo->core_id != cpu_topo->core_id)
continue;
cpumask_set_cpu(cpuid, &cpu_topo->thread_sibling);
if (cpu != cpuid)
cpumask_set_cpu(cpu, &cpuid_topo->thread_sibling);
cpumask_set_cpu(cpu, &cpuid_topo->thread_sibling);
}
}