Re: [Qemu-ppc] [PATCH v3 14/14] pci: Tidy up PCI host bridges

[Michael S. Tsirkin]

On Thu, Jul 05, 2012 at 12:15:04PM +0200, Andreas Färber wrote:
> Am 05.07.2012 11:53, schrieb Paolo Bonzini:
> > Il 05/07/2012 00:34, Andreas Färber ha scritto:
> >>>> Just to clarify: replacing upcasts which are always safe
> >>>> with downcasts which can fail is what I consider especially ugly.
> >> As per Anthony the parent field in the QOM instance structs is not
> >> supposed to be touched (cf. object.h). We mark it /*< private >*/ so
> >> that it doesn't even show up in gtk-doc documentation. If it is unused,
> >> its name becomes irrelevant and could even be "reserved" if we so
> >> wanted. Renaming it to whatever proves that all old references are gone.
> > 
> > I disagree with removing static checks whenever possible.
> > 
> >> Background is that qdev and QOM work differently with regards to
> >> inheritance: as mentioned in the preceding patch, for qdev the parent
> >> was (had to be) identified by name and could be anywhere in the struct;
> > 
> > Not entirely true, being at the beginning of the struct is already
> > enforced by using DO_UPCAST (which is admittedly a strange name for a
> > downcast macro) instead of container_of.
> 
> If you look at the patchset you will find that it was not properly enforced!
> 
> Andreas

Yes DO_UPCAST is IMO evil and should go - everyone can eiter use dynamic
QOM types with lookup by name; or stop passing nonsafe void * pointers
around and use container_of consistently.


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