[RFC, powerpc] perf/hv-24x7 set the attr group to NULL if events failed to be initialized

[Sukadev Bhattiprolu]

Michael Ellerman [mpe at ellerman.id.au] wrote:
| On Sun, 2015-15-02 at 09:42:57 UTC, Li Zhong wrote:
| > This patch moves the three events groups to the end of the attr groups,
| > and if create_events_from_catalog() fails to set their attributes, we
| > set them to NULL in attr_groups.
| 
| But why are we continuing at all if create_events_from_catalog() fails?
| 
| Shouldn't that just be a fatal error and we bail?

Well, even if create_events_from_catalog() fails, we can continue to use
the 24x7 events, rather clumsily, as long as the catalog is readable.  i.e.
parse /sys/bus/event_source/devices/hv_24x7/interface/catalog to find event
offset and run:

	perf stat -C 0 -e hv_24x7/domain=2,offset=8,core=0/ workload
Suka