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); >> 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
