From mboxrd@z Thu Jan  1 00:00:00 1970
From: Arnaldo Carvalho de Melo <acme-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Subject: Re: [PATCH 1/3] dwarves print: Fix holes accounting
Date: Wed, 16 Dec 2015 15:10:20 -0300
Message-ID: <20151216181020.GE6843@kernel.org>
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To: Jiri Olsa <jolsa-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: Joe Mario <jmario-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, dwarves-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
List-Id: dwarves@vger.kernel.org

Em Wed, Dec 16, 2015 at 03:05:32PM -0300, Arnaldo Carvalho de Melo escreveu:
> Em Wed, Dec 16, 2015 at 02:58:39PM -0300, Arnaldo Carvalho de Melo escreveu:
> > Em Tue, Dec 08, 2015 at 11:47:04PM +0100, Jiri Olsa escreveu:
> > > Sometimes the hole could be missing, try to bypass
> > > this issue by comparing last and current offsets.

> > Can you provide an example of before and after this change? What real
> > case triggered this?

<SNIP>

> > > +++ b/dwarves_fprintf.c
> > > @@ -1268,6 +1268,17 @@ size_t class__fprintf(struct class *class, const struct cu *cu,
> > >  		}
> > >  		pos = tag__class_member(tag_pos);
> > >  
> > > +		/*
> > > +		 * Sometimes the hole could be missing, try to bypass
> > > +		 * this issue by comparing last and current offsets.
> > > +		 */
> > > +		if (last) {
> > > +			uint32_t tmp = last->byte_offset + last->byte_size + last->hole;
> > > +
> > > +			if (pos->byte_offset > tmp)
> > > +				sum_holes += pos->byte_offset - tmp;
> > > +		}
 
> I mean, how could this be? last->hole then would have been wrong,
> miscalculated, looking at where it is calculated now...

Yeah, class__find_holes() should have properly calculated last->hole so
that (last->byte_offset + last->byte_size + last->hole) ==
pos->byte_offset.

- Arnaldo
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