On 27-11-16, 00:13, Sebastian Andrzej Siewior wrote:
> Install the callbacks via the state machine.
> 
> Cc: "Rafael J. Wysocki" <r...@rjwysocki.net>
> Cc: Viresh Kumar <viresh.ku...@linaro.org>
> Cc: linux...@vger.kernel.org
> Signed-off-by: Sebastian Andrzej Siewior <bige...@linutronix.de>
> ---
>  drivers/cpufreq/acpi-cpufreq.c | 93 
> ++++++++++++++++++++----------------------
>  1 file changed, 45 insertions(+), 48 deletions(-)
> 
> diff --git a/drivers/cpufreq/acpi-cpufreq.c b/drivers/cpufreq/acpi-cpufreq.c
> index 297e9128fe9f..2c29cbaca7b5 100644
> --- a/drivers/cpufreq/acpi-cpufreq.c
> +++ b/drivers/cpufreq/acpi-cpufreq.c
> @@ -536,46 +536,33 @@ static void free_acpi_perf_data(void)
>       free_percpu(acpi_perf_data);
>  }
>  
> -static int boost_notify(struct notifier_block *nb, unsigned long action,
> -                   void *hcpu)
> +static int cpufreq_boost_online(unsigned int cpu)
> +{
> +     const struct cpumask *cpumask;
> +
> +     cpumask = get_cpu_mask(cpu);
> +     /*
> +      * On the CPU_UP path we simply keep the boost-disable flag
> +      * in sync with the current global state.
> +      */
> +     boost_set_msrs(acpi_cpufreq_driver.boost_enabled, cpumask);
> +     return 0;
> +}
> +
> +static int cpufreq_boost_down_prep(unsigned int cpu)
>  {
> -     unsigned cpu = (long)hcpu;
>       const struct cpumask *cpumask;
>  
>       cpumask = get_cpu_mask(cpu);
>  
>       /*
>        * Clear the boost-disable bit on the CPU_DOWN path so that
> -      * this cpu cannot block the remaining ones from boosting. On
> -      * the CPU_UP path we simply keep the boost-disable flag in
> -      * sync with the current global state.
> +      * this cpu cannot block the remaining ones from boosting.
>        */
> -
> -     switch (action) {
> -     case CPU_DOWN_FAILED:
> -     case CPU_DOWN_FAILED_FROZEN:
> -     case CPU_ONLINE:
> -     case CPU_ONLINE_FROZEN:
> -             boost_set_msrs(acpi_cpufreq_driver.boost_enabled, cpumask);
> -             break;
> -
> -     case CPU_DOWN_PREPARE:
> -     case CPU_DOWN_PREPARE_FROZEN:
> -             boost_set_msrs(1, cpumask);
> -             break;
> -
> -     default:
> -             break;
> -     }
> -
> -     return NOTIFY_OK;
> +     boost_set_msrs(1, cpumask);
> +     return 0;
>  }
>  
> -
> -static struct notifier_block boost_nb = {
> -     .notifier_call          = boost_notify,
> -};
> -
>  /*
>   * acpi_cpufreq_early_init - initialize ACPI P-States library
>   *
> @@ -922,37 +909,47 @@ static struct cpufreq_driver acpi_cpufreq_driver = {
>       .attr           = acpi_cpufreq_attr,
>  };
>  
> +static enum cpuhp_state acpi_cpufreq_online;
> +
>  static void __init acpi_cpufreq_boost_init(void)
>  {
> -     if (boot_cpu_has(X86_FEATURE_CPB) || boot_cpu_has(X86_FEATURE_IDA)) {
> -             msrs = msrs_alloc();
> +     int ret;
>  
> -             if (!msrs)
> -                     return;
> +     if (!(boot_cpu_has(X86_FEATURE_CPB) || boot_cpu_has(X86_FEATURE_IDA)))
> +             return;
>  
> -             acpi_cpufreq_driver.set_boost = set_boost;
> -             acpi_cpufreq_driver.boost_enabled = boost_state(0);
> +     msrs = msrs_alloc();
>  
> -             cpu_notifier_register_begin();
> +     if (!msrs)
> +             return;
>  
> -             /* Force all MSRs to the same value */
> -             boost_set_msrs(acpi_cpufreq_driver.boost_enabled,
> -                            cpu_online_mask);

Why isn't this required anymore ?

> +     acpi_cpufreq_driver.set_boost = set_boost;
> +     acpi_cpufreq_driver.boost_enabled = boost_state(0);
>  
> -             __register_cpu_notifier(&boost_nb);
> -
> -             cpu_notifier_register_done();
> +     /*
> +      * This calls the online callback on all online cpu and forces all
> +      * MSRs to the same value.
> +      */
> +     ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "cpufreq/acpi:online",
> +                             cpufreq_boost_online, cpufreq_boost_down_prep);
> +     if (ret < 0) {
> +             pr_err("acpi_cpufreq: failed to register hotplug callbacks\n");
> +             msrs_free(msrs);

If 'msrs = NULL' is required to be done in the _exit() routine, then it should
be done here as well. Right?

> +             return;
>       }
> +     acpi_cpufreq_online = ret;
>  }
>  
>  static void acpi_cpufreq_boost_exit(void)
>  {
> -     if (msrs) {
> -             unregister_cpu_notifier(&boost_nb);
> +     if (!msrs)
> +             return;
>  
> -             msrs_free(msrs);
> -             msrs = NULL;
> -     }
> +     if (acpi_cpufreq_online >= 0)
> +             cpuhp_remove_state_nocalls(acpi_cpufreq_online);
> +
> +     msrs_free(msrs);
> +     msrs = NULL;
>  }
>  
>  static int __init acpi_cpufreq_init(void)
> -- 
> 2.10.2

-- 
viresh

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