Commit 9af57b7a ("IB/cm: Add basic performance counters") introduced a
bug in how the reference count for cm_class.subsys.kobj was handled:
the path that released a device did a kobject_put() on that kobject, but
there was no kobject_get() in the path the handles adding a device. So
the reference count ended up too low, which leads to bad things. Fix up
and simplify the reference counting to avoid this.
(Actually, I introduced the bug when fixing the patch up to match some
of Greg's kobject changes, but who's counting)
Signed-off-by: Roland Dreier <rolandd@cisco.com>
7c7a9bccd2