lkml.org 
[lkml]   [2014]   [Oct]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
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





\
 
 \ /
  Last update: 2014-10-14 21:21    [W:0.616 / U:0.112 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site