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

[Igor Mammedov]

On Sun, 25 Oct 2020 16:24:44 +0100
Greg Kurz <groug@kaod.org> wrote:

> 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.

probably I was clear enough, I didn't suggest to move spapr_drc_detach()
to pre_plug time but rather do a bit of surgery along the lines:

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 2db810f73a..59a229b4fa 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -3474,6 +3474,11 @@ static void spapr_memory_pre_plug(HotplugHandler 
*hotplug_dev, DeviceState *dev,
         return;
     }
 
+    get drc
+    if (!spapr_drc_attachable(drc)) {
+        error out
+    }
+
     if (is_nvdimm) {
         spapr_nvdimm_validate(hotplug_dev, NVDIMM(dev), size, &local_err);
         if (local_err) {
diff --git a/hw/ppc/spapr_drc.c b/hw/ppc/spapr_drc.c
index fe998d8108..ae049bc202 100644
--- a/hw/ppc/spapr_drc.c
+++ b/hw/ppc/spapr_drc.c
@@ -371,14 +371,16 @@ static void prop_get_fdt(Object *obj, Visitor *v, const 
char *name,
     } while (fdt_depth != 0);
 }
 
-void spapr_drc_attach(SpaprDrc *drc, DeviceState *d, Error **errp)
+
+bool spapr_drc_attachable(SpaprDrc *drc)
+{
+   return !drc->dev;
+}
+
+void spapr_drc_attach(SpaprDrc *drc, DeviceState *d)
 {
     trace_spapr_drc_attach(spapr_drc_index(drc));
 
-    if (drc->dev) {
-        error_setg(errp, "an attached device is still awaiting release");
-        return;
-    }
     g_assert((drc->state == SPAPR_DRC_STATE_LOGICAL_UNUSABLE)
              || (drc->state == SPAPR_DRC_STATE_PHYSICAL_POWERON));

> 
> 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
> > > 
> > > 
> > >   
> >   
>