[PATCH V3 05/19] OMAP3+: voltage: use IS_ERR_OR_NULL
Nishanth Menon
nm at ti.com
Sun Mar 6 21:56:08 EST 2011
Russell King - ARM Linux wrote, on 03/06/2011 01:48 PM:
> On Sun, Mar 06, 2011 at 08:15:06AM +0530, Nishanth Menon wrote:
>> my_dumb_func(){
>> struct voltagedomain *vdata = NULL;
>> if (cpu_is_omap3630()_) {
>> vdata = omap_voltage_domain_lookup("mpu")
>> }
>> /* forgot to add other cpu types or a else case */
>> /* do other things */
>> me_volt=omap_voltage_get_nom_volt(vdata);
>> /* do things with me_volt */
>> }
>>
>> Sorry, but i think the check, even if seems superfluous is sane IMHO.
>> even if the above code worked on 3630, it'd fail on o4/3430 without the
>> check, it can even crash. and given that we've all seen our fair share
>> of developers who develop for one platform without consideration that
>> the rest of the world uses others as well... I do feel cases like above
>> example might infact be a reality.
>
> But normal practice is to check the return value from functions before
> it's used. So:
>
> my_dumb_func(){
> struct voltagedomain *vdata = NULL;
> if (cpu_is_omap3630()) {
> vdata = omap_voltage_domain_lookup("mpu")
> }
> /* forgot to add other cpu types or a else case */
>
> + if (!vdata)
> + return some error;
>
> /* do other things */
> me_volt=omap_voltage_get_nom_volt(vdata);
> /* do things with me_volt */
> }
>
> is the right way to deal with this. Pushing the primary error checking
> down into sub-functions is stupid - where does it stop? Do you check
> me_volt for errors? Do you get functions which use me_volt to check for
> errors from that too?
>
> It's a silly idea. Put the primary error checking in the function which
> gets the return value. Don't bury it in sub-functions.
I agree with you on this - sub functions esp static ones should able to
trust the parameters passed to it by callers. for the moment, I suggest
we drop this patch from this series - it has no functional impact to the
overall goal which I was attempting to achieve. Cleanups of the voltage,
smartreflex layers are an ongoing activity currently and should be
takenup as part of it.
--
Regards,
Nishanth Menon
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