Hi, Thomas,
What do you think about this patch? Other archs also do the same thing
except those support hotplug CPU#0.
grep hotpluggable arch -rwI
arch/riscv/kernel/setup.c: cpu->hotpluggable = cpu_has_hotplug(i);
arch/powerpc/kernel/sysfs.c: BUG_ON(!c->hotpluggable);
arch/powerpc/kernel/sysfs.c: c->hotpluggable = 1;
arch/powerpc/kernel/sysfs.c: if (cpu_online(cpu) || c->hotpluggable) {
arch/arm/kernel/setup.c: cpuinfo->cpu.hotpluggable =
platform_can_hotplug_cpu(cpu);
arch/sh/kernel/topology.c: c->hotpluggable = 1;
arch/ia64/kernel/topology.c: * CPEI target, then it is hotpluggable
arch/ia64/kernel/topology.c: sysfs_cpus[num].cpu.hotpluggable = 1;
arch/xtensa/kernel/setup.c: cpu->hotpluggable = !!i;
arch/s390/kernel/smp.c: c->hotpluggable = 1;
arch/mips/kernel/topology.c: c->hotpluggable = 1;
arch/arm64/kernel/cpuinfo.c: * In case the boot CPU is hotpluggable,
we record its initial state and
arch/arm64/kernel/setup.c: cpu->hotpluggable = cpu_can_disable(i);
arch/x86/kernel/topology.c: per_cpu(cpu_devices,
num).cpu.hotpluggable = 1;
On Thu, Jul 16, 2020 at 6:38 PM Huacai Chen <chenhc@xxxxxxxxxx> wrote:
>
> Now CPU#0 is not hotpluggable on MIPS, so prevent to create /sys/devices
> /system/cpu/cpu0/online which confuses some user-space tools.
>
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Huacai Chen <chenhc@xxxxxxxxxx>
> ---
> arch/mips/kernel/topology.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/mips/kernel/topology.c b/arch/mips/kernel/topology.c
> index cd3e1f8..08ad637 100644
> --- a/arch/mips/kernel/topology.c
> +++ b/arch/mips/kernel/topology.c
> @@ -20,7 +20,7 @@ static int __init topology_init(void)
> for_each_present_cpu(i) {
> struct cpu *c = &per_cpu(cpu_devices, i);
>
> - c->hotpluggable = 1;
> + c->hotpluggable = !!i;
> ret = register_cpu(c, i);
> if (ret)
> printk(KERN_WARNING "topology_init: register_cpu %d "
> --
> 2.7.0
>
