Re: [PATCH for-5.0 0/8] ppc: Consolidate QOM links and pointers to the same object

[Cédric Le Goater]

On 15/11/2019 12:53, Greg Kurz wrote:
> There's a recurring pattern in the code where a const link is added to a
> newly instanciated object and the link is then used in the object's realize
> function to keep a pointer to the QOM entity which the link points to.
> 
> void create_obj_B(Object *obj_a)
> {
>     Object *obj_b;
> 
>     obj_b = object_new(TYPE_B);
>     object_property_add_const_link(obj_b, "link-to-a", obj_a, &error_abort);
> }
> 
> void object_B_realize(DeviceState *dev, Error **errp)
> {
>     Object *obj_a;
> 
>     obj_a = object_property_get_link(OBJECT(dev), "link-to-a", errp);
>     if (!obj_a) {
>         return;
>     }
> 
>     obj_b->obj_a = A(obj_a); // If obj_b->obj_a is changed, the link property
>                              // still points to the original obj_a that was
>                              // passed to object_property_add_const_link()
> }
> 
> Confusing bugs could arise if the pointer and the link go out of sync for
> some reason. This can be avoided if the property is defined to directly use
> the pointer with object_property_add_link() and object_property_set_link().
> 
> This series just does that for all occurences of the fragile pattern in
> the XIVE and PNV code.

Can we use DEFINE_PROP_LINK() instead ?

C. 


> 
> --
> Greg
> 
> ---
> 
> Greg Kurz (8):
>       xive: Link "cpu" property to XiveTCTX::cs pointer
>       xive: Link "xive" property to XiveSource::xive pointer
>       xive: Link "xive" property to XiveEndSource::xrtr pointer
>       ppc/pnv: Link "psi" property to PnvLpc::psi pointer
>       ppc/pnv: Link "psi" property to PnvOCC::psi pointer
>       ppc/pnv: Link "chip" property to PnvHomer::chip pointer
>       ppc/pnv: Link "chip" property to PnvCore::chip pointer
>       ppc/pnv: Link "chip" property to PnvXive::chip pointer
> 
> 
>  hw/intc/pnv_xive.c        |   29 +++++++++-----------
>  hw/intc/spapr_xive.c      |    8 +++---
>  hw/intc/xive.c            |   65 
> ++++++++++++++++++++++-----------------------
>  hw/ppc/pnv.c              |   32 +++++++++++-----------
>  hw/ppc/pnv_core.c         |   18 +++++++-----
>  hw/ppc/pnv_homer.c        |   24 +++++++++--------
>  hw/ppc/pnv_lpc.c          |   23 ++++++++--------
>  hw/ppc/pnv_occ.c          |   23 ++++++++--------
>  hw/ppc/pnv_psi.c          |    3 +-
>  include/hw/ppc/pnv.h      |    2 +
>  include/hw/ppc/pnv_core.h |    2 +
>  11 files changed, 115 insertions(+), 114 deletions(-)
>