On Thu, Nov 17, 2016 at 07:35:25PM +0100, Sebastian Andrzej Siewior wrote:
> Install the callbacks via the state machine. Setup and teardown are handled
> by the hotplug core.
> 
> Cc: Fenghua Yu <fenghua...@intel.com>
> Cc: Jean Delvare <jdelv...@suse.com>
> Cc: Guenter Roeck <li...@roeck-us.net>
> Cc: linux-hw...@vger.kernel.org
> Signed-off-by: Sebastian Andrzej Siewior <bige...@linutronix.de>

Install, modprobe, modprobe -r, modprobe,

[24078.179118] ------------[ cut here ]------------
[24078.179124] WARNING: CPU: 0 PID: 14 at fs/sysfs/dir.c:31 
sysfs_warn_dup+0x6e/0x80
[24078.179125] sysfs: cannot create duplicate filename
'/devices/platform/coretemp.0'

and many more of those.

I can not test the other hwmon drivers in this series, but I would assume
that they have the same problem.

Guenter

> ---
>  drivers/hwmon/coretemp.c | 74 
> +++++++++++++++---------------------------------
>  1 file changed, 23 insertions(+), 51 deletions(-)
> 
> diff --git a/drivers/hwmon/coretemp.c b/drivers/hwmon/coretemp.c
> index 6a27eb2fed17..390038884f9e 100644
> --- a/drivers/hwmon/coretemp.c
> +++ b/drivers/hwmon/coretemp.c
> @@ -676,7 +676,7 @@ static bool is_any_core_online(struct platform_data 
> *pdata)
>       return false;
>  }
>  
> -static void get_core_online(unsigned int cpu)
> +static int coretemp_cpu_online(unsigned int cpu)
>  {
>       struct cpuinfo_x86 *c = &cpu_data(cpu);
>       struct platform_device *pdev = coretemp_get_pdev(cpu);
> @@ -688,12 +688,12 @@ static void get_core_online(unsigned int cpu)
>        * without thermal sensors will be filtered out.
>        */
>       if (!cpu_has(c, X86_FEATURE_DTHERM))
> -             return;
> +             return 0;
>  
>       if (!pdev) {
>               /* Check the microcode version of the CPU */
>               if (chk_ucode_version(cpu))
> -                     return;
> +                     return 0;
>  
>               /*
>                * Alright, we have DTS support.
> @@ -703,7 +703,7 @@ static void get_core_online(unsigned int cpu)
>                */
>               err = coretemp_device_add(cpu);
>               if (err)
> -                     return;
> +                     return 0;
>               /*
>                * Check whether pkgtemp support is available.
>                * If so, add interfaces for pkgtemp.
> @@ -716,9 +716,10 @@ static void get_core_online(unsigned int cpu)
>        * So, just add interfaces for this core.
>        */
>       coretemp_add_core(cpu, 0);
> +     return 0;
>  }
>  
> -static void put_core_offline(unsigned int cpu)
> +static int coretemp_cpu_offline(unsigned int cpu)
>  {
>       int i, indx;
>       struct platform_data *pdata;
> @@ -726,7 +727,7 @@ static void put_core_offline(unsigned int cpu)
>  
>       /* If the physical CPU device does not exist, just return */
>       if (!pdev)
> -             return;
> +             return 0;
>  
>       pdata = platform_get_drvdata(pdev);
>  
> @@ -734,7 +735,7 @@ static void put_core_offline(unsigned int cpu)
>  
>       /* The core id is too big, just return */
>       if (indx > MAX_CORE_DATA - 1)
> -             return;
> +             return 0;
>  
>       if (pdata->core_data[indx] && pdata->core_data[indx]->cpu == cpu)
>               coretemp_remove_core(pdata, indx);
> @@ -747,7 +748,7 @@ static void put_core_offline(unsigned int cpu)
>        */
>       for_each_sibling(i, cpu) {
>               if (i != cpu) {
> -                     get_core_online(i);
> +                     coretemp_cpu_online(i);
>                       /*
>                        * Display temperature sensor data for one HT sibling
>                        * per core only, so abort the loop after one such
> @@ -764,38 +765,20 @@ static void put_core_offline(unsigned int cpu)
>        */
>       if (!is_any_core_online(pdata))
>               coretemp_device_remove(cpu);
> +     return 0;
>  }
>  
> -static int coretemp_cpu_callback(struct notifier_block *nfb,
> -                              unsigned long action, void *hcpu)
> -{
> -     unsigned int cpu = (unsigned long) hcpu;
> -
> -     switch (action) {
> -     case CPU_ONLINE:
> -     case CPU_DOWN_FAILED:
> -             get_core_online(cpu);
> -             break;
> -     case CPU_DOWN_PREPARE:
> -             put_core_offline(cpu);
> -             break;
> -     }
> -     return NOTIFY_OK;
> -}
> -
> -static struct notifier_block coretemp_cpu_notifier __refdata = {
> -     .notifier_call = coretemp_cpu_callback,
> -};
> -
>  static const struct x86_cpu_id __initconst coretemp_ids[] = {
>       { X86_VENDOR_INTEL, X86_FAMILY_ANY, X86_MODEL_ANY, X86_FEATURE_DTHERM },
>       {}
>  };
>  MODULE_DEVICE_TABLE(x86cpu, coretemp_ids);
>  
> +static enum cpuhp_state coretemp_hp_online;
> +
>  static int __init coretemp_init(void)
>  {
> -     int i, err;
> +     int err;
>  
>       /*
>        * CPUID.06H.EAX[0] indicates whether the CPU has thermal
> @@ -809,44 +792,33 @@ static int __init coretemp_init(void)
>       if (err)
>               goto exit;
>  
> -     cpu_notifier_register_begin();
> -     for_each_online_cpu(i)
> -             get_core_online(i);
> +     err = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "hwmon/coretemp:online",
> +                             coretemp_cpu_online, coretemp_cpu_offline);
> +     if (err < 0)
> +             goto exit_driver_unreg;
> +     coretemp_hp_online = err;
>  
>  #ifndef CONFIG_HOTPLUG_CPU
>       if (list_empty(&pdev_list)) {
> -             cpu_notifier_register_done();
>               err = -ENODEV;
> -             goto exit_driver_unreg;
> +             goto exit_hp_unreg;
>       }
>  #endif
> -
> -     __register_hotcpu_notifier(&coretemp_cpu_notifier);
> -     cpu_notifier_register_done();
>       return 0;
>  
>  #ifndef CONFIG_HOTPLUG_CPU
> +exit_hp_unreg:
> +     cpuhp_remove_state(coretemp_hp_online);
> +#endif
>  exit_driver_unreg:
>       platform_driver_unregister(&coretemp_driver);
> -#endif
>  exit:
>       return err;
>  }
>  
>  static void __exit coretemp_exit(void)
>  {
> -     struct pdev_entry *p, *n;
> -
> -     cpu_notifier_register_begin();
> -     __unregister_hotcpu_notifier(&coretemp_cpu_notifier);
> -     mutex_lock(&pdev_list_mutex);
> -     list_for_each_entry_safe(p, n, &pdev_list, list) {
> -             platform_device_unregister(p->pdev);
> -             list_del(&p->list);
> -             kfree(p);
> -     }
> -     mutex_unlock(&pdev_list_mutex);
> -     cpu_notifier_register_done();
> +     cpuhp_remove_state(coretemp_hp_online);
>       platform_driver_unregister(&coretemp_driver);
>  }
>  

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