linux-kernel - Re: [PATCH 1/3] hwmon: (dell-smm) Fail probing when cooling device registration fails

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Message-ID: <ea06f15d-cb22-1d5d-9437-59d595e24e43@gmx.de>
Date:   Sun, 21 Aug 2022 21:11:24 +0200
From:   Armin Wolf <W_Armin@....de>
To:     Pali Rohár <pali@...nel.org>
Cc:     jdelvare@...e.com, linux@...ck-us.net, linux-hwmon@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] hwmon: (dell-smm) Fail probing when cooling device
 registration fails

Am 21.08.22 um 17:41 schrieb Pali Rohár:

> On Sunday 21 August 2022 17:17:11 Armin Wolf wrote:
>> Previously, it was thought that failing to register a cooling device
>> would not be critical, so the probing was not aborted in such a case.
>> This however would lead to userspace being unable to rely on those
>> cooling devices, since they might not represent all fans being present.
>> Fix that by failing probing when cooling device registration fails.
> This patch does not fix address this issue fully. CONFIG_THERMAL can be
> disabled during compile time and then cooling device would not be
> registered too.

I though of the cooling device feature as being optional "as a whole".
So when CONFIG_THERMAL is disabled during compile time, the driver does
not create any cooling devices. If however CONFIG_THERMAL was enabled
during compile time, the driver should fail probing if it cannot register
all cooling devices.

Armin Wolf

>> Tested on a Dell Inspiron 3505.
>>
>> Fixes: e0d3f7cb2606 ("hwmon: (dell-smm) Add cooling device support")
>> Signed-off-by: Armin Wolf <W_Armin@....de>
>> ---
>>   drivers/hwmon/dell-smm-hwmon.c | 4 +---
>>   1 file changed, 1 insertion(+), 3 deletions(-)
>>
>> diff --git a/drivers/hwmon/dell-smm-hwmon.c b/drivers/hwmon/dell-smm-hwmon.c
>> index 7f8d95dd2717..1dab7591576a 100644
>> --- a/drivers/hwmon/dell-smm-hwmon.c
>> +++ b/drivers/hwmon/dell-smm-hwmon.c
>> @@ -1013,12 +1013,10 @@ static int __init dell_smm_init_hwmon(struct device *dev)
>>
>>   		data->fan[i] = true;
>>
>> -		/* the cooling device is not critical, ignore failures */
>>   		if (IS_REACHABLE(CONFIG_THERMAL)) {
>>   			err = dell_smm_init_cdev(dev, i);
>>   			if (err < 0)
>> -				dev_warn(dev, "Failed to register cooling device for fan %u\n",
>> -					 i + 1);
>> +				return err;
>>   		}
>>
>>   		data->fan_nominal_speed[i] = devm_kmalloc_array(dev, data->i8k_fan_max + 1,
>> --
>> 2.30.2
>>