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    SubjectRe: [PATCH v2] perf tools: fix off-by-one error in maps
    Em Tue, Oct 07, 2014 at 05:17:12PM +0200, Stephane Eranian escreveu:
    > On Tue, Oct 7, 2014 at 5:10 PM, Arnaldo Carvalho de Melo
    > <acme@redhat.com> wrote:
    > > Em Tue, Oct 07, 2014 at 04:17:41PM +0200, Stephane Eranian escreveu:
    > >> On Tue, Oct 7, 2014 at 4:00 PM, Arnaldo Carvalho de Melo
    > >> >> +++ b/tools/perf/util/map.c
    > >> >> @@ -752,7 +752,7 @@ struct map *maps__find(struct rb_root *maps, u64 ip)
    > >> >> m = rb_entry(parent, struct map, rb_node);
    > >> >> if (ip < m->start)
    > >> >> p = &(*p)->rb_left;
    > >> >> - else if (ip > m->end)
    > >> >> + else if (ip >= m->end)
    > >> >> p = &(*p)->rb_right;
    > >> >> else
    > >> >> return m;

    > >> > 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.

    > >> It is okay but then we need to be consistent all across. This is not
    > >> the case today.
    > >> I mentioned the cases I ran into.

    > > Ok, and provided a patch doing the way I thought was confusing, now its
    > > my turn to use that info and come up with a patch, ok, will do that.

    > You got it! ;->

    struct vm_area_struct {
    /* The first cache line has the info for VMA tree walking. */

    unsigned long vm_start; /* Our start address within vm_mm. */
    unsigned long vm_end; /* The first byte after our end address
    within vm_mm. */

    So these guys have been doing this far longer than me, I guess I'll bow
    to this convention.

    But by renaming map->end to map->end_ and looking at all the usage of
    it, there are some inconsistencies...

    Like symbol->{start,end} is of the [start,end] case, and to be
    consistent with above needs to also move to [start,end[, will cook a
    patch and send for review.

    - Arnaldo





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