Re: [PATCH v2] perf tools: fix off-by-one error in maps

From: Chuck Ebbert
Date: Tue Oct 07 2014 - 14:58:48 EST


On Tue, 7 Oct 2014 11:00:50 -0300
Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> wrote:

> I keep thinking that this change is making things unclear.
>
> I.e. the _start_ of a map (map->start) is _in_ the map, and the _end_
> of a map (map->end) is _in_ the map as well.
>
> if (addr > m->end)
>
> is shorter than:
>
> if (addr >= m->end)
>
> "start" and "end" should have the same rule applied, i.e. if one is in,
> the other is in as well.
>
> Etc.
>

But the convention used in the memory management code is that "end" is
the next byte after the memory region. This gives you:

size = end - start
end = start + size

Using a different convention here will just confuse people used to the
way it's done everywhere else.
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