Re: [PATCH] cpu: mark cpu_possible_mask as __ro_after_init

[Guenter Roeck]

On Mon, Feb 05, 2024 at 01:01:19PM +0300, Alexey Dobriyan wrote:
> cpu_possible_mask is by definition "cpus which could be hotplugged
> without reboot" -- property which is fixed after kernel enumerates
> motheboard capabilities and hardware configuration.
> 
> Signed-off-by: Alexey Dobriyan <adobriyan@xxxxxxxxx>
> ---
> 
>  kernel/cpu.c |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> --- a/kernel/cpu.c
> +++ b/kernel/cpu.c
> @@ -3107,10 +3107,10 @@ const DECLARE_BITMAP(cpu_all_bits, NR_CPUS) = CPU_BITS_ALL;
>  EXPORT_SYMBOL(cpu_all_bits);
>  
>  #ifdef CONFIG_INIT_ALL_POSSIBLE
> -struct cpumask __cpu_possible_mask __read_mostly
> +struct cpumask __cpu_possible_mask __ro_after_init;
>  	= {CPU_BITS_ALL};

I guess you didn't compile test this code.

Guenter

>  #else
> -struct cpumask __cpu_possible_mask __read_mostly;
> +struct cpumask __cpu_possible_mask __ro_after_init;
>  #endif
>  EXPORT_SYMBOL(__cpu_possible_mask);
>