On 04/22/2014 03:56 PM, Chen Gang wrote:
> On 04/22/2014 03:21 PM, Pavel Machek wrote:
>> On Tue 2014-04-22 09:29:20, Chen Gang wrote:
>>> For do_div(), it need 'u64' type, which means the outside must be sure
>>> of 'start' is not bigger than 'stop', or it will report warning.
>>>
>>> Even if 'start' was really bigger than 'stop', it would print incorrect
>>> information, but for kernel, it still can continue, so use WARN_ON() is
>>> enough.
>>>
>>> The related warning (with allmodconfig for unicore32):
>>>
>>> CC kernel/power/hibernate.o
>>> kernel/power/hibernate.c: In function ‘swsusp_show_speed’:
>>> kernel/power/hibernate.c:237: warning: comparison of distinct pointer
>>> types lacks a cast
>>>
>>>
>>
>> Certainly better, but
>>
>>> - s64 elapsed_centisecs64;
>>> + u64 elapsed_centisecs64;
>>> int centisecs;
>>> int k;
>>> int kps;
>>>
>>> elapsed_centisecs64 = timeval_to_ns(stop) - timeval_to_ns(start);
>>> + WARN_ON((s64)elapsed_centisecs64 < 0);
How about to use one line comments instead of WARN_ON()?
/*
* If "(s64)elapsed_centisecs64 < 0", it will print long elapsed
* time, it is obvious enough to user for what went wrong.
*/
>>> do_div(elapsed_centisecs64, NSEC_PER_SEC / 100);
>>> centisecs = elapsed_centisecs64;
>>
>> ...do we need to do the WARN_ON()? Only result of underflow will be
>> very long elapsed time reported... that does not sound too
>> bad. ... and it will be quite obvious what went wrong.
>> Pavel
>>
>
> Hmm... that sounds reasonable to me. If no any other reply within 2
> days, I shall send patch v3 for it.
>
> BTW: sorry, I guess I can not finish allmodconfig for unicore32 within
> this month (2014-04-30) -- at present I only finish 40-50%, I
> will/should try to finish it within next month.
>
>
> Thanks.
>
--
Chen Gang
Open, share, and attitude like air, water, and life which God blessed
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