[PATCH v2 3/3] ARM: Check if a CPU has gone offline

[Rob Herring]

On Thu, Mar 27, 2014 at 10:38 AM, Ashwin Chaugule
<ashwin.chaugule at linaro.org> wrote:
> PSCIv0.2 adds a new function called AFFINITY_INFO, which
> can be used to query if a specified CPU has actually gone
> offline. Calling this function via cpu_kill ensures that
> a CPU has quiesced after a call to cpu_die.
>
> Signed-off-by: Ashwin Chaugule <ashwin.chaugule at linaro.org>
> ---
>  arch/arm/kernel/psci_smp.c | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
>
> diff --git a/arch/arm/kernel/psci_smp.c b/arch/arm/kernel/psci_smp.c
> index 570a48c..2407843 100644
> --- a/arch/arm/kernel/psci_smp.c
> +++ b/arch/arm/kernel/psci_smp.c
> @@ -66,6 +66,24 @@ void __ref psci_cpu_die(unsigned int cpu)
>         /* We should never return */
>         panic("psci: cpu %d failed to shutdown\n", cpu);
>  }
> +
> +int __ref psci_cpu_kill(unsigned int cpu)
> +{
> +       int err = 0;
> +
> +       if (psci_ops.affinity_info) {

You can save a level of indentation with:

if (!psci_ops.affinity_info)
    return 1;

This fixes the return as no affinity_info call (i.e. 0.1 PSCI) should not fail.

> +               err = psci_ops.affinity_info(cpu, 0);

You need to convert the logical cpu (0..N) to the mpidr value (cpu_logical_map).

> +
> +               if (err != 1) {

1 should have a define (in the uapi header).

Which reminds me, all the PSCI return code defines should also be in
that header.

> +                       pr_err("psci: Cannot kill CPU:%d, psci ret val: %d\n",
> +                                       cpu, err);
> +                       /* Make platform_cpu_kill() fail. */
> +                       return 0;
> +               }
> +       }
> +       return err;
> +}
> +
>  #endif
>
>  bool __init psci_smp_available(void)
> @@ -78,5 +96,6 @@ struct smp_operations __initdata psci_smp_ops = {
>         .smp_boot_secondary     = psci_boot_secondary,
>  #ifdef CONFIG_HOTPLUG_CPU
>         .cpu_die                = psci_cpu_die,
> +       .cpu_kill               = psci_cpu_kill,
>  #endif
>  };
> --
> 1.8.3.2
>