Re: [Xen-devel] [PATCH v4 09/10] xen/arm: Free memory allocated for sibling/core maps on CPU hot-unplug

[Julien Grall <julien.grall@xxxxxxx>]

Hi Mirela,

On 15/05/18 12:44, Mirela Simonovic wrote:
> The memory allocated in setup_cpu_sibling_map() when a CPU is hotplugged
> has to be freed when the CPU is hot-unplugged. This is done in
> remove_cpu_sibling_map() and called when the CPU dies. The call to
> remove_cpu_sibling_map() is made from a notifier callback when
> CPU_DEAD event is received.
>
> Signed-off-by: Mirela Simonovic <mirela.simonovic@xxxxxxxxxx>
Acked-by: Julien Grall <julien.grall@xxxxxxx>

Cheers,

> ---
> CC: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> CC: Julien Grall <julien.grall@xxxxxxx>
> ---
> Changes in v3:
> -Use notifier to trigger remove_cpu_sibling_map() when the CPU dies.
>
> Changes in v4:
> -Initialize cpu_smpboot notifier at presmp_init rather than init phase
>   to cover the case where a secondary CPU dies beforehand the initcall
> -Added newline before the return in cpu_smpboot_notifier_init()
> -Fix indentation in cpu_smpboot_callback() definition
> ---
>   xen/arch/arm/smpboot.c | 36 ++++++++++++++++++++++++++++++++++++
>   1 file changed, 36 insertions(+)
>
> diff --git a/xen/arch/arm/smpboot.c b/xen/arch/arm/smpboot.c
> index ad1f6b751b..cf3a4ce659 100644
> --- a/xen/arch/arm/smpboot.c
> +++ b/xen/arch/arm/smpboot.c
> @@ -89,6 +89,12 @@ static void setup_cpu_sibling_map(int cpu)
>       cpumask_set_cpu(cpu, per_cpu(cpu_core_mask, cpu));
>   }
>   
> +static void remove_cpu_sibling_map(int cpu)
> +{
> +    free_cpumask_var(per_cpu(cpu_sibling_mask, cpu));
> +    free_cpumask_var(per_cpu(cpu_core_mask, cpu));
> +}
> +
>   void __init
>   smp_clear_cpu_maps (void)
>   {
> @@ -499,6 +505,36 @@ void __cpu_die(unsigned int cpu)
>       smp_mb();
>   }
>   
> +static int cpu_smpboot_callback(struct notifier_block *nfb,
> +                                unsigned long action,
> +                                void *hcpu)
> +{
> +    unsigned int cpu = (unsigned long)hcpu;
> +
> +    switch ( action )
> +    {
> +    case CPU_DEAD:
> +        remove_cpu_sibling_map(cpu);
> +        break;
> +    default:
> +        break;
> +    }
> +
> +    return NOTIFY_DONE;
> +}
> +
> +static struct notifier_block cpu_smpboot_nfb = {
> +    .notifier_call = cpu_smpboot_callback,
> +};
> +
> +static int __init cpu_smpboot_notifier_init(void)
> +{
> +    register_cpu_notifier(&cpu_smpboot_nfb);
> +
> +    return 0;
> +}
> +presmp_initcall(cpu_smpboot_notifier_init);
> +
>   /*
>    * Local variables:
>    * mode: C
--
Julien Grall

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