linux-kernel - Re: [PATCH v2] LoongArch: Do not create sysfs control file for io master CPUs

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Message-ID: <CAAhV-H6nT5AMrgWa-FPO_cbvQbSajeoUvDskKGVys9-hsNcGvg@mail.gmail.com>
Date:   Sun, 9 Oct 2022 14:15:28 +0800
From:   Huacai Chen <chenhuacai@...nel.org>
To:     Tiezhu Yang <yangtiezhu@...ngson.cn>
Cc:     WANG Xuerui <kernel@...0n.name>, loongarch@...ts.linux.dev,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] LoongArch: Do not create sysfs control file for io
 master CPUs

Queued for loongarch-next, thanks.

Huacai

On Sun, Oct 9, 2022 at 9:23 AM Tiezhu Yang <yangtiezhu@...ngson.cn> wrote:
>
> Now io master CPUs are not hotpluggable on LoongArch, in the current code,
> only /sys/devices/system/cpu/cpu0/online is not created, let us set the
> hotpluggable field of all the io master CPUs as 0, then prevent to create
> sysfs control file for the other io master CPUs which confuses some user
> space tools. This is similar with commit 9cce844abf07 ("MIPS: CPU#0 is not
> hotpluggable").
>
> Signed-off-by: Tiezhu Yang <yangtiezhu@...ngson.cn>
> ---
>  arch/loongarch/include/asm/bootinfo.h | 5 +++++
>  arch/loongarch/kernel/smp.c           | 5 -----
>  arch/loongarch/kernel/topology.c      | 3 ++-
>  3 files changed, 7 insertions(+), 6 deletions(-)
>
> diff --git a/arch/loongarch/include/asm/bootinfo.h b/arch/loongarch/include/asm/bootinfo.h
> index 8e5881b..ed0910e 100644
> --- a/arch/loongarch/include/asm/bootinfo.h
> +++ b/arch/loongarch/include/asm/bootinfo.h
> @@ -40,4 +40,9 @@ extern unsigned long fw_arg0, fw_arg1, fw_arg2;
>  extern struct loongson_board_info b_info;
>  extern struct loongson_system_configuration loongson_sysconf;
>
> +static inline bool io_master(int cpu)
> +{
> +       return test_bit(cpu, &loongson_sysconf.cores_io_master);
> +}
> +
>  #endif /* _ASM_BOOTINFO_H */
> diff --git a/arch/loongarch/kernel/smp.c b/arch/loongarch/kernel/smp.c
> index b5fab30..781a4d4 100644
> --- a/arch/loongarch/kernel/smp.c
> +++ b/arch/loongarch/kernel/smp.c
> @@ -240,11 +240,6 @@ void loongson3_smp_finish(void)
>
>  #ifdef CONFIG_HOTPLUG_CPU
>
> -static bool io_master(int cpu)
> -{
> -       return test_bit(cpu, &loongson_sysconf.cores_io_master);
> -}
> -
>  int loongson3_cpu_disable(void)
>  {
>         unsigned long flags;
> diff --git a/arch/loongarch/kernel/topology.c b/arch/loongarch/kernel/topology.c
> index ab1a75c..caa7cd8 100644
> --- a/arch/loongarch/kernel/topology.c
> +++ b/arch/loongarch/kernel/topology.c
> @@ -5,6 +5,7 @@
>  #include <linux/node.h>
>  #include <linux/nodemask.h>
>  #include <linux/percpu.h>
> +#include <asm/bootinfo.h>
>
>  static DEFINE_PER_CPU(struct cpu, cpu_devices);
>
> @@ -40,7 +41,7 @@ static int __init topology_init(void)
>         for_each_present_cpu(i) {
>                 struct cpu *c = &per_cpu(cpu_devices, i);
>
> -               c->hotpluggable = !!i;
> +               c->hotpluggable = !io_master(i);
>                 ret = register_cpu(c, i);
>                 if (ret < 0)
>                         pr_warn("topology_init: register_cpu %d failed (%d)\n", i, ret);
> --
> 2.1.0
>