Re: CVS commit: src/sys/dev

[Iain Hibbert <plunky%rya-online.net@localhost>]

On Fri, 27 May 2011, Masao Uebayashi wrote:

> On Thu, May 26, 2011 at 8:24 PM, Iain Hibbert 
> <plunky%rya-online.net@localhost> wrote:
> > On Thu, 26 May 2011, Masao Uebayashi wrote:
> >
> >> On Thu, May 26, 2011 at 5:39 PM, Iain Hibbert 
> >> <plunky%rya-online.net@localhost> wrote:
> >> > On Thu, 26 May 2011, Masao Uebayashi wrote:
> >> >> - I can't think of how cfdriver decls can lead to type inconsistency 
> >> >> bugs.
> >> >
> >> > Ok, somebody makes a mistake and writes
> >> >
> >> > extern struct cfdata foo_cd;
> >> >
> >> > and it works by chance because the address was zero anyway, then later
> >> > something else is changed around and all of a sudden, an innocent code
> >> > causes a kernel panic..
> >>
> >> cfdriver must exist for either embedded/module forms.  If not, it
> >> should cause link error (if I'm not missing anything).
> >
> > Of course, it would exist.. that is the bug
> >
> > file a: /* generated by config(1) */
> >        struct cfdriver foo_cd;
> >
> > file b: /* generated by an inattentive programmer */
> >        extern struct cfdata foo_cd;
>
> I see.  Let's fix hundreds of these instances now.

well, it is hypothetical of course - you wrote

 "I can't think of how cfdriver decls can lead to type inconsistency bugs."

and I have shown you one pretty obvious way in which that can happen..

iain