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SubjectRe: kfifo: possible weird violation of what should be invariant
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 >   sure, the code seems to work, but allowing the internal values of a
> kfifo to contain invalid values on a regular basis would seem to make
> a mess of, say, tracing or debugging. making sure that offset values
> actually lie within their valid range would seem to be one of those
> ASSERT() things that should always be true, should it not? is there a
> reason the design is like this?

Actually I believe having the values be free-running without clamping
them makes the code much simpler -- the reason being that you preserve
the invariant of "in" always being ahead of "out". If you reduce the
pointers modulo the size, then you end up having a lot of code that has
two cases: one to handle "in > out", and one to handle "in < out because
in has wrapped and out hasn't yet".

- R.
--
Roland Dreier <rolandd@cisco.com>
For corporate legal information go to:
http://www.cisco.com/web/about/doing_business/legal/cri/index.html


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