Messages in this thread | | | Date | Sun, 29 Nov 1998 17:36:29 +0100 (CET) | From | MOLNAR Ingo <> | Subject | Re: [tiny patch] Timeout overflow in select() |
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On Sun, 29 Nov 1998, Andrea Arcangeli wrote:
> On Sat, 28 Nov 1998, Stephane Belmon wrote:
> >One more comment on your patch: Generally speaking, this style of checking > >overflows _after_ they happen makes me a little nervous. It works in many > >cases, like what you do: "a+b". If you're doing "a+b+c", testing things > >like the sign of the result doesn't catch all overflows; nor if you have > >multiplications. So a seemingly innocent change made later on could break > >the test: a case of bad "bug locality". > > I can add a comment but I don' t care too much about this issue. Following > this thought we should not write kernel code at all ;). Everything can be > screwed up by a mistake from somebody like me ;>>.
we definitely care about 'bug locality' and related issues. Remember, schedule_timeout() was introduced exactly due to the same thing. (apart from the slight schedule() speedup which is just a nice side-effect) Writing kernel code that works is one thing, but one of the real tasks is to write kernel code that has a smaller chance to be broken later on. Just witness how much we avoid type casts ...
-- mingo
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