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

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Message-ID: <20141008155348.GD2256@redhat.com>
Date:	Wed, 8 Oct 2014 12:53:48 -0300
From:	Arnaldo Carvalho de Melo <acme@...hat.com>
To:	Chuck Ebbert <cebbert.lkml@...il.com>
Cc:	Namhyung Kim <namhyung@...nel.org>,
	Stephane Eranian <eranian@...gle.com>,
	linux-kernel@...r.kernel.org, jolsa@...hat.com,
	peterz@...radead.org, mingo@...e.hu, dsahern@...il.com
Subject: Re: [PATCH v2] perf tools: fix off-by-one error in maps

Em Tue, Oct 07, 2014 at 01:58:38PM -0500, Chuck Ebbert escreveu:
> On Tue, 7 Oct 2014 11:00:50 -0300
> Arnaldo Carvalho de Melo <acme@...hat.com> 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.

So we should continue using some confusing convention because that is
the way that things are? :-\

- Arnaldo
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