Messages in this thread | | | From | "Rafael J. Wysocki" <> | Subject | Re: [PATCH] kernel/power/hibernate.c: be sure of 'start' is not bigger than 'stop' | Date | Mon, 21 Apr 2014 22:43:10 +0200 |
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On Monday, April 21, 2014 10:09:30 PM Pavel Machek wrote: > On Mon 2014-04-21 21:40:27, 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. > > > > 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 > > > > Signed-off-by: Chen Gang <gang.chen.5i5j@gmail.com> > > > { > > - s64 elapsed_centisecs64; > > + u64 elapsed_centisecs64; > > int centisecs; > > int k; > > int kps; > > > > elapsed_centisecs64 = timeval_to_ns(stop) - timeval_to_ns(start); > > + if ((s64)elapsed_centisecs64 < 0) { > > + printk(KERN_ERR "PM: stop: %llu < start %llu\n", > > + timeval_to_ns(stop), timeval_to_ns(start)); > > + return; > > + } > > do_div(elapsed_centisecs64, NSEC_PER_SEC / 100); > > centisecs = elapsed_centisecs64; > > if (centisecs == 0) > > Quite a lot of code to shut up warning in mostly debugging > function... is there alternative method of shutting it up? Have you > seen < 0 values in wild?
No, I don't think so. This is a purely theoretical problem that never happens in practice, because all of the callers do the right thing.
Rafael
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