Clang warning in drivers/hwmon/scmi-hwmon.c

Clang warning in drivers/hwmon/scmi-hwmon.c

[Nathan Chancellor]

Hi Sundeep and others,

A group of us are trying to clean up all the warnings we see with an
'allyesconfig' arm64 build done with Clang and this one came up:

drivers/hwmon/scmi-hwmon.c:59:24: warning: address of array 'sensor->name' will always evaluate to 'true' [-Wpointer-bool-conversion]
        if (sensor && sensor->name)
                   ~~ ~~~~~~~~^~~~
1 warning generated.

Would it be appropriate to just delete that check or does the check
need to be adjusted in some way (such as checking for the first value
'sensor->name[0]')? Either option technically solves the warning but I
don't have the hardware to check if this breaks the driver.

Thanks,
Nathan

Re: Clang warning in drivers/hwmon/scmi-hwmon.c

[Guenter Roeck]

On 09/14/2018 10:10 PM, Nathan Chancellor wrote:
> Hi Sundeep and others,
> 
> A group of us are trying to clean up all the warnings we see with an
> 'allyesconfig' arm64 build done with Clang and this one came up:
> 
> drivers/hwmon/scmi-hwmon.c:59:24: warning: address of array 'sensor->name' will always evaluate to 'true' [-Wpointer-bool-conversion]
>          if (sensor && sensor->name)
>                     ~~ ~~~~~~~~^~~~
> 1 warning generated.
> 
> Would it be appropriate to just delete that check or does the check
> need to be adjusted in some way (such as checking for the first value
> 'sensor->name[0]')? Either option technically solves the warning but I
> don't have the hardware to check if this breaks the driver.
> 

Presumably the check is supposed to validate the content of the data structure,
so dropping the test doesn't seem to make sense. However, one could argue
that, if the _content_ is to be checked, it should be checked earlier,
before the data pointer is stored (ie in scmi_hwmon_probe()).

Given that, I'll be happy to accept a patch to just drop the check; it
does not change the behavior of the driver, after all. If a real validation
is desirable, it can be added (into the probe function) with a separate patch.

Thanks,
Guenter

Re: Clang warning in drivers/hwmon/scmi-hwmon.c

[Nathan Chancellor]

On Sat, Sep 15, 2018 at 04:37:20PM -0700, Guenter Roeck wrote:
> On 09/14/2018 10:10 PM, Nathan Chancellor wrote:
> > Hi Sundeep and others,
> > 
> > A group of us are trying to clean up all the warnings we see with an
> > 'allyesconfig' arm64 build done with Clang and this one came up:
> > 
> > drivers/hwmon/scmi-hwmon.c:59:24: warning: address of array 'sensor->name' will always evaluate to 'true' [-Wpointer-bool-conversion]
> >          if (sensor && sensor->name)
> >                     ~~ ~~~~~~~~^~~~
> > 1 warning generated.
> > 
> > Would it be appropriate to just delete that check or does the check
> > need to be adjusted in some way (such as checking for the first value
> > 'sensor->name[0]')? Either option technically solves the warning but I
> > don't have the hardware to check if this breaks the driver.
> > 
> 
> Presumably the check is supposed to validate the content of the data structure,
> so dropping the test doesn't seem to make sense. However, one could argue
> that, if the _content_ is to be checked, it should be checked earlier,
> before the data pointer is stored (ie in scmi_hwmon_probe()).
> 
> Given that, I'll be happy to accept a patch to just drop the check; it
> does not change the behavior of the driver, after all. If a real validation
> is desirable, it can be added (into the probe function) with a separate patch.
> 
> Thanks,
> Guenter
> 

Thank you for the quick response and clarification, patch sent.

Nathan