Re: [PATCH 3/3] ath9k: fix 'side effect in macro' smatch warning

[Ben Greear <greearb@candelatech.com>]

On 06/22/2012 04:55 AM, Dan Carpenter wrote:
> On Fri, Jun 22, 2012 at 10:17:23AM +0300, Kalle Valo wrote:
>> Rajkumar Manoharan<rmanohar@qca.qualcomm.com>  writes:
>>
>>> ath9k_get_et_stats() warn: side effect in macro
>>> 'AWDATA' doing 'i++'
>>>
>>> Cc: Ben Greear<greearb@candelatech.com>
>>> Signed-off-by: Rajkumar Manoharan<rmanohar@qca.qualcomm.com>
>>
>> [...]
>>
>>>   	do {								\
>>> -		data[i++] = sc->debug.stats.txstats[PR_QNUM(WME_AC_BE)].elem; \
>>> -		data[i++] = sc->debug.stats.txstats[PR_QNUM(WME_AC_BK)].elem; \
>>> -		data[i++] = sc->debug.stats.txstats[PR_QNUM(WME_AC_VI)].elem; \
>>> -		data[i++] = sc->debug.stats.txstats[PR_QNUM(WME_AC_VO)].elem; \
>>> +		data[i+0] = sc->debug.stats.txstats[PR_QNUM(WME_AC_BE)].elem; \
>>> +		data[i+1] = sc->debug.stats.txstats[PR_QNUM(WME_AC_BK)].elem; \
>>> +		data[i+2] = sc->debug.stats.txstats[PR_QNUM(WME_AC_VI)].elem; \
>>> +		data[i+3] = sc->debug.stats.txstats[PR_QNUM(WME_AC_VO)].elem; \
>>> +		i += 4; \
>>>   	} while (0)
>>
>> I agree with Ben, this is a useless change as the end result is still
>> the same (the side effect is that i is increased with four). You are
>> just hiding that from smatch and once smatch is fixed it will warn again
>> about the same thing.
>>
>> I recommend fixing this properly so that the macro doesn't have any side
>> effects.
>
> Uh.  Sorry, also I thought I had pushed a fix to add this to the
> ignored macro list, but I forgot.  I've pushed it now.

The whole point of the macro is to have an affect.  This is not a general
purpose macro..it's very specific to this local logic.

I don't think folks should be so dogmatic about these sorts of things.

Thanks,
Ben


-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com