On Mon, Dec 04, 2017 at 11:20:29PM +0100, Linus Walleij wrote:
> If the thermal subsystem returne -EPROBE_DEFER or any other error
> when hwmon calls devm_thermal_zone_of_sensor_register(), this is
> silently ignored.
> 
> I ran into this with an incorrectly defined thermal zone, making
> it non-existing and thus this call failed with -EPROBE_DEFER
> assuming it would appear later. The sensor was still added
> which is incorrect: sensors must strictly be added after the
> thermal zones, so deferred probe must be respected.
> 
> Signed-off-by: Linus Walleij <[email protected]>
> ---
>  drivers/hwmon/hwmon.c | 17 +++++++++++++----
>  1 file changed, 13 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/hwmon/hwmon.c b/drivers/hwmon/hwmon.c
> index c9790e2c3440..6d1cb6b47490 100644
> --- a/drivers/hwmon/hwmon.c
> +++ b/drivers/hwmon/hwmon.c
> @@ -143,6 +143,7 @@ static int hwmon_thermal_add_sensor(struct device *dev,
>                                   struct hwmon_device *hwdev, int index)
>  {
>       struct hwmon_thermal_data *tdata;
> +     struct thermal_zone_device *tzd;
>  
>       tdata = devm_kzalloc(dev, sizeof(*tdata), GFP_KERNEL);
>       if (!tdata)
> @@ -151,8 +152,10 @@ static int hwmon_thermal_add_sensor(struct device *dev,
>       tdata->hwdev = hwdev;
>       tdata->index = index;
>  
> -     devm_thermal_zone_of_sensor_register(&hwdev->dev, index, tdata,
> -                                          &hwmon_thermal_ops);
> +     tzd = devm_thermal_zone_of_sensor_register(&hwdev->dev, index, tdata,
> +                                                &hwmon_thermal_ops);
> +     if (IS_ERR(tzd))
> +             return PTR_ERR(tzd);

This won't work because devm_thermal_zone_of_sensor_register() returns
-ENODEV if CONFIG_THERMAL_OF is disabled. We'll have to check for
-EPROBE_DEFER and only return this specific error, but ignore all others.

Thanks,
Guenter

>  
>       return 0;
>  }
> @@ -621,14 +624,20 @@ __hwmon_device_register(struct device *dev, const char 
> *name, void *drvdata,
>                               if (!chip->ops->is_visible(drvdata, hwmon_temp,
>                                                          hwmon_temp_input, j))
>                                       continue;
> -                             if (info[i]->config[j] & HWMON_T_INPUT)
> -                                     hwmon_thermal_add_sensor(dev, hwdev, j);
> +                             if (info[i]->config[j] & HWMON_T_INPUT) {
> +                                     err = hwmon_thermal_add_sensor(dev,
> +                                                             hwdev, j);
> +                                     if (err)
> +                                             goto free_device;
> +                             }
>                       }
>               }
>       }
>  
>       return hdev;
>  
> +free_device:
> +     device_unregister(hdev);
>  free_hwmon:
>       kfree(hwdev);
>  ida_remove:
> -- 
> 2.14.3
> 
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