makedumpfile -g with recent kernels

[Atsushi Kumagai]

Hello Stefan,

On Thu, 02 Aug 2012 10:23:13 +0200
Stefan Bader <stefan.bader at canonical.com> wrote:

> >   static void
> >   adjust_member_offset(Dwarf_Die *die)
> >   {
> >           long offset;
> > 
> >           if (dwarf_info.member_offset == NOT_FOUND_STRUCTURE)     // this comparison is always true
> >                   return;
> >           if (!get_data_member_location(die, &offset))
> >                   return;
> >           dwarf_info.member_offset += offset;
> >   }
> > 
> > At least, the change below works fine without regression.
> > 
> > 
> > diff --git a/dwarf_info.c b/dwarf_info.c
> > index 583df53..03e4c90 100644
> > --- a/dwarf_info.c
> > +++ b/dwarf_info.c
> > @@ -520,7 +520,9 @@ search_member(Dwarf_Die *die)
> >                         /*
> >                          * Get the member offset.
> >                          */
> > -                       if (!get_data_member_location(walker, &offset))
> > +                       if (dwarf_tag(die) == DW_TAG_union_type)
> 
> Hm, should that not be die_type to check what the walker is on? And in that case
> it seems that check was made just before... So maybe it would be ok to assume 0
> as the offset when getting here...?

As you said, the walker will be a member of union or struct when reaching here,
because is_anonymous_container() already checked the walker.

However, get_data_member_location() must succeed if the walker is a member of struct
while it doesn't succeed if the walker is a member of union.
That's why I added the code to check whether the walker is a member of union or not.


Thanks
Atsushi Kumagai

> > +                               offset = 0;
> > +                       else if (!get_data_member_location(walker, &offset))
> >                                 continue;
> >                         dwarf_info.member_offset = offset;
> >                         return TRUE;
> > 
> > 
> > Unless you have better way to fix this issue, I'll merge your patch into
> > the next version with the change above.
> > 
> > By the way, this fix enable us also to get the offset of page._mapcount and
> > page.private, it's very helpful for the new method of free page filtering.
> > 
> >   http://lists.infradead.org/pipermail/kexec/2012-June/006441.html
> > 
> > 
> > Thanks
> > Atsushi Kumagai
> > 
> 
>