linux-kernel - Re: [PATCH] regulator: core: fix error path for regulator_set_voltage

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Date:   Mon, 18 Mar 2019 19:10:23 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Steve Twiss <stwiss.opensource@...semi.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Maciej Purski <m.purski@...subg.com>,
        Support Opensource <support.opensource@...semi.com>
Subject: Re: [PATCH] regulator: core: fix error path for
 regulator_set_voltage_unlocked

18.03.2019 19:03, Dmitry Osipenko пишет:
> 18.03.2019 18:32, Steve Twiss пишет:
>> During several error paths in the function
>> regulator_set_voltage_unlocked() the value of 'ret' can take on negative
>> error values. However, in calls that go through the 'goto out' statement,
>> this return value is lost and return 0 is used instead, indicating a
>> 'pass'.
>>
>> There are several cases where this function should legitimately return a
>> fail instead of a pass: one such case includes constraints check during
>> voltage selection in the call to regulator_check_voltage(), which can
>> have -EINVAL for the case when an unsupported voltage is incorrectly
>> requested. In that case, -22 is expected as the return value, not 0.
>>
>> Fixes: 9243a195be7a ("regulator: core: Change voltage setting path")
>> Signed-off-by: Steve Twiss <stwiss.opensource@...semi.com>
>> ---
>>  drivers/regulator/core.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
>> index 68473d0..caf8743 100644
>> --- a/drivers/regulator/core.c
>> +++ b/drivers/regulator/core.c
>> @@ -3326,7 +3326,7 @@ static int regulator_set_voltage_unlocked(struct regulator *regulator,
>>  		goto out2;
>>  
>>  out:
>> -	return 0;
>> +	return ret;
>>  out2:
>>  	voltage->min_uV = old_min_uV;
>>  	voltage->max_uV = old_max_uV;
>>
> 
> Looks like a good catch.
> 
> Probably will be a bit better to write this as:
> 
>         /* for not coupled regulators this will just set the voltage */
>         ret = regulator_balance_voltage(rdev, state);
> -       if (ret < 0)
> -               goto out2;
> -
> +       if (ret < 0) {
> +               voltage->min_uV = old_min_uV;
> +               voltage->max_uV = old_max_uV;
> +       }
>  out:
> -       return 0;
> -out2:
> -       voltage->min_uV = old_min_uV;
> -       voltage->max_uV = old_max_uV;
> -
>         return ret;
>  }
> 

Also, probably won't hurt to add a stable tag "Cc: stable <stable@...r.kernel.org>" to get the fix backported.