Re: [groeck-staging:hwmon-next 13/13] drivers/hwmon/gpio-fan.c:250:6: warning: variable 'ret' is used uninitialized whenever 'if' condition is false

[Alexander Stein <alexander.stein@ew.tq-group.com>]

Hi Guenter,

Am Mittwoch, 9. April 2025, 04:51:35 CEST schrieb Guenter Roeck:
> Alexander,
> 
> On 4/8/25 19:11, kernel test robot wrote:
> > tree:   https://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging.git hwmon-next
> > head:   d6b1492c9c2e7f2659b63a165ea45ab556c0df0c
> > commit: d6b1492c9c2e7f2659b63a165ea45ab556c0df0c [13/13] hwmon: (gpio-fan) Add regulator support
> > config: riscv-randconfig-001-20250409 (https://download.01.org/0day-ci/archive/20250409/202504091047.biuX8Kl2-lkp@intel.com/config)
> > compiler: clang version 21.0.0git (https://github.com/llvm/llvm-project 92c93f5286b9ff33f27ff694d2dc33da1c07afdd)
> > reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250409/202504091047.biuX8Kl2-lkp@intel.com/reproduce)
> > 
> > If you fix the issue in a separate patch/commit (i.e. not just a new version of
> > the same patch/commit), kindly add following tags
> > | Reported-by: kernel test robot <lkp@intel.com>
> > | Closes: https://lore.kernel.org/oe-kbuild-all/202504091047.biuX8Kl2-lkp@intel.com/
> > 
> > All warnings (new ones prefixed by >>):
> > 
> >>> drivers/hwmon/gpio-fan.c:250:6: warning: variable 'ret' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
> >       250 |         if (val == 0)
> >           |             ^~~~~~~~
> >     drivers/hwmon/gpio-fan.c:255:9: note: uninitialized use occurs here
> >       255 |         return ret ? ret : count;
> >           |                ^~~
> >     drivers/hwmon/gpio-fan.c:250:2: note: remove the 'if' if its condition is always true
> >       250 |         if (val == 0)
> >           |         ^~~~~~~~~~~~~
> >       251 |                 ret = set_fan_speed(fan_data, fan_data->num_speed - 1);
> >     drivers/hwmon/gpio-fan.c:237:9: note: initialize the variable 'ret' to silence this warning
> >       237 |         int ret;
> >           |                ^
> >           |                 = 0
> >     1 warning generated.
> > 
> 
> I dropped the patch from linux-next. Please fix and make sure there are no
> such problems before resubmitting.

Oh, surprising. A W=1 build on my machine doesn't raise this warning. I'm not
sure if this is specific to riscv or clang. Nevertheless this is correct and
I'll send a fixed one.

Thanks and best regards
Alexander

> Thanks,
> Guenter
> > 
> > vim +250 drivers/hwmon/gpio-fan.c
> > 
> > d6fe1360f42e86 Simon Guinot       2010-10-22  230
> > c490c63e9505a3 Julia Lawall       2016-12-22  231  static ssize_t pwm1_enable_store(struct device *dev,
> > c490c63e9505a3 Julia Lawall       2016-12-22  232  				 struct device_attribute *attr,
> > d6fe1360f42e86 Simon Guinot       2010-10-22  233  				 const char *buf, size_t count)
> > d6fe1360f42e86 Simon Guinot       2010-10-22  234  {
> > d6fe1360f42e86 Simon Guinot       2010-10-22  235  	struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
> > d6fe1360f42e86 Simon Guinot       2010-10-22  236  	unsigned long val;
> > d6b1492c9c2e7f Alexander Stein    2025-04-08  237  	int ret;
> > d6fe1360f42e86 Simon Guinot       2010-10-22  238
> > 179c4fdb565dd2 Frans Meulenbroeks 2012-01-04  239  	if (kstrtoul(buf, 10, &val) || val > 1)
> > d6fe1360f42e86 Simon Guinot       2010-10-22  240  		return -EINVAL;
> > d6fe1360f42e86 Simon Guinot       2010-10-22  241
> > d6fe1360f42e86 Simon Guinot       2010-10-22  242  	if (fan_data->pwm_enable == val)
> > d6fe1360f42e86 Simon Guinot       2010-10-22  243  		return count;
> > d6fe1360f42e86 Simon Guinot       2010-10-22  244
> > d6fe1360f42e86 Simon Guinot       2010-10-22  245  	mutex_lock(&fan_data->lock);
> > d6fe1360f42e86 Simon Guinot       2010-10-22  246
> > d6fe1360f42e86 Simon Guinot       2010-10-22  247  	fan_data->pwm_enable = val;
> > d6fe1360f42e86 Simon Guinot       2010-10-22  248
> > d6fe1360f42e86 Simon Guinot       2010-10-22  249  	/* Disable manual control mode: set fan at full speed. */
> > d6fe1360f42e86 Simon Guinot       2010-10-22 @250  	if (val == 0)
> > d6b1492c9c2e7f Alexander Stein    2025-04-08  251  		ret = set_fan_speed(fan_data, fan_data->num_speed - 1);
> > d6fe1360f42e86 Simon Guinot       2010-10-22  252
> > d6fe1360f42e86 Simon Guinot       2010-10-22  253  	mutex_unlock(&fan_data->lock);
> > d6fe1360f42e86 Simon Guinot       2010-10-22  254
> > d6b1492c9c2e7f Alexander Stein    2025-04-08  255  	return ret ? ret : count;
> > d6fe1360f42e86 Simon Guinot       2010-10-22  256  }
> > d6fe1360f42e86 Simon Guinot       2010-10-22  257
> > 
> > :::::: The code at line 250 was first introduced by commit
> > :::::: d6fe1360f42e86262153927986dea6502daff703 hwmon: add generic GPIO fan driver
> > 
> > :::::: TO: Simon Guinot <sguinot@lacie.com>
> > :::::: CC: Guenter Roeck <guenter.roeck@ericsson.com>
> > 
> 
> 


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