Re: [PATCH 4/5] spapr: Pass &error_abort when getting some PC DIMM properties

[Greg Kurz <groug@kaod.org>]

On Fri, 23 Oct 2020 21:15:09 +0200
Igor Mammedov <imammedo@redhat.com> wrote:

> On Mon, 19 Oct 2020 10:48:41 +0200
> Greg Kurz <groug@kaod.org> wrote:
> 
> > Both PC_DIMM_SLOT_PROP and PC_DIMM_ADDR_PROP are defined in the
> > default property list of the PC DIMM device class:
> > 
> >     DEFINE_PROP_UINT64(PC_DIMM_ADDR_PROP, PCDIMMDevice, addr, 0),
> > 
> >     DEFINE_PROP_INT32(PC_DIMM_SLOT_PROP, PCDIMMDevice, slot,
> >                       PC_DIMM_UNASSIGNED_SLOT),
> > 
> > They should thus be always gettable for both PC DIMMs and NVDIMMs.
> > An error in getting them can only be the result of a programming
> > error. It doesn't make much sense to propagate the error in this
> > case. Abort instead.
> > 
> > Signed-off-by: Greg Kurz <groug@kaod.org>
> 
> Reviewed-by: Igor Mammedov <imammedo@redhat.com>
> 
> TODO for future,
> get rid of local_err in spapr_memory_plug() altogether, it should not fail.
> it needs moving check from spapr_drc_attach() to spapr_memory_pre_plug() time.
> 
> that will clear up (a bit) road for dropping errp in spapr_memory_plug()

Igor,

I could find time to look a bit into attaching DRCs at pre-plug and I
think this isn't possible. The problem is that there doesn't seem to be
a reverse operation for pre-plug. If realize fails for the DIMM device,
spapr_drc_detach() wouldn't be called, which would be wrong.

Am I missing something ?

> > ---
> >  hw/ppc/spapr.c |   17 +++--------------
> >  1 file changed, 3 insertions(+), 14 deletions(-)
> > 
> > diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> > index 1b173861152f..62f217a6b914 100644
> > --- a/hw/ppc/spapr.c
> > +++ b/hw/ppc/spapr.c
> > @@ -3443,19 +3443,13 @@ static void spapr_memory_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
> >  
> >      if (!is_nvdimm) {
> >          addr = object_property_get_uint(OBJECT(dimm),
> > -                                        PC_DIMM_ADDR_PROP, &local_err);
> > -        if (local_err) {
> > -            goto out_unplug;
> > -        }
> > +                                        PC_DIMM_ADDR_PROP, &error_abort);
> >          spapr_add_lmbs(dev, addr, size,
> >                         spapr_ovec_test(ms->ov5_cas, OV5_HP_EVT),
> >                         &local_err);
> >      } else {
> >          slot = object_property_get_int(OBJECT(dimm),
> > -                                       PC_DIMM_SLOT_PROP, &local_err);
> > -        if (local_err) {
> > -            goto out_unplug;
> > -        }
> > +                                       PC_DIMM_SLOT_PROP, &error_abort);
> >          /* We should have valid slot number at this point */
> >          g_assert(slot >= 0);
> >          spapr_add_nvdimm(dev, slot, &local_err);
> > @@ -3634,7 +3628,6 @@ static void spapr_memory_unplug_request(HotplugHandler *hotplug_dev,
> >                                          DeviceState *dev, Error **errp)
> >  {
> >      SpaprMachineState *spapr = SPAPR_MACHINE(hotplug_dev);
> > -    Error *local_err = NULL;
> >      PCDIMMDevice *dimm = PC_DIMM(dev);
> >      uint32_t nr_lmbs;
> >      uint64_t size, addr_start, addr;
> > @@ -3650,11 +3643,7 @@ static void spapr_memory_unplug_request(HotplugHandler *hotplug_dev,
> >      nr_lmbs = size / SPAPR_MEMORY_BLOCK_SIZE;
> >  
> >      addr_start = object_property_get_uint(OBJECT(dimm), PC_DIMM_ADDR_PROP,
> > -                                         &local_err);
> > -    if (local_err) {
> > -        error_propagate(errp, local_err);
> > -        return;
> > -    }
> > +                                          &error_abort);
> >  
> >      /*
> >       * An existing pending dimm state for this DIMM means that there is an
> > 
> > 
> > 
>