fixed bug in wl_list

[Iskren Chernev]

Well, the actual problem is that something was removed twice. And I know
where this place is, but I couldn't know if you would like to remove
elements multiple times with no problems, or treat the list very carefully
and remove elements only once. But then there should be a way to know if an
element is already in a list or not. So if there is a way to know that, why
not make a check inside wl_list_remove, just to make sure.

I'll fix it the way you want it to be :)

Regards,
Iskren

On Sat, Mar 12, 2011 at 1:07 PM, Marty Jack <martyj19 at comcast.net> wrote:

>
>
> On 03/11/2011 07:32 PM, Iskren Chernev wrote:
> > Hello,
> >
> > I found a bug and fixed it with the patch :)
> >
> > *to reproduce:*
> > run compositor on top of x11
> >
> > repeat
> >    run flower
> >    drag & drop it a little
> >    move the pointer in and out of the compositor/flower
> >    Ctrl+C the flower client
> >
> > it would break eventually
> >
> > *problem:*
> > I found that the linked list surface->destroy_listener_list got corrupted
> at some point (it was not circular any more, strange next/prev etc), which
> causes the crash.
> >
> > *solution:*
> > The problem was in wl_list_remove -- when you erase an element, you don't
> mark it as 'erased', by setting prev/next to NULL for example. Then if you
> erase it again the list becomes corrupt. I nullified the prev/next and check
> in the begining of wl_list_remove for not-in-list elements and just ignore
> them. That seems to fix it.
> >
> > Regards,
> > Iskren
> >
> >
> >
> > _______________________________________________
> > wayland-devel mailing list
> > wayland-devel at lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/wayland-devel
>
> Unfortunately your fix only papers over the real problem, which is that the
> list got corrupted at some point.  It would not actually solve the problem.
>  The source of the corruption needs to be located and fixed; it could be
> removing something twice, inserting something twice, or the like.  You could
> push ahead with this if you were interested.
> _______________________________________________
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> wayland-devel at lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/wayland-devel
>
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